dbx/crates/dbx-core/src/transfer.rs

use regex::Regex;
use serde::{Deserialize, Serialize};
use std::collections::{HashMap, HashSet};
use tokio::sync::RwLock;

use crate::connection::{config_for_pool_key, AppState, PoolKind};
use crate::db;
use crate::db::mongo_driver::MongoDocumentResult;
use crate::models::connection::DatabaseType;
use crate::object_source_sql::{build_executable_object_source_statements, EditableObjectSourceSqlInput};
use crate::query::{agent_execute_query_params, pool_error_action, PoolErrorAction, QueryExecutionOptions};
use crate::sql::{split_sql_statements, split_sql_statements_for_database};
use crate::sql_dialect::{qualified_transfer_table, quote_transfer_identifier};

static CANCELLED: std::sync::LazyLock<RwLock<HashSet<String>>> =
    std::sync::LazyLock::new(|| RwLock::new(HashSet::new()));
static OCEANBASE_MYSQL_TABLE_OPTION_RE: std::sync::LazyLock<Regex> = std::sync::LazyLock::new(|| {
    Regex::new(r"(?i)\b(?:AUTO_INCREMENT_MODE|REPLICA_NUM|USE_BLOOM_FILTER|TABLET_SIZE|PCTFREE)\s*=")
        .expect("valid OceanBase MySQL table option regex")
});
static MYSQL_COLLATE_CLAUSE_RE: std::sync::LazyLock<Regex> = std::sync::LazyLock::new(|| {
    Regex::new(r"(?i)\bCOLLATE\s*=?\s*([A-Za-z0-9_]+)\b").expect("valid MySQL COLLATE clause regex")
});

const MAX_TRANSFER_WRITE_SQL_BYTES: usize = 512 * 1024;
const MAX_SQLSERVER_INSERT_ROWS: usize = 1000;
const MAX_ORACLE_INSERT_ALL_ROWS: usize = 500;
const MAX_ORACLE_MERGE_ROWS: usize = 500;
const TRANSFER_TARGET_TABLE_LOOKUP_LIMIT: usize = 1000;

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub(crate) struct SqlBatchLimits {
    max_rows: usize,
    target_sql_bytes: usize,
    hard_sql_bytes: Option<usize>,
}

impl SqlBatchLimits {
    pub(crate) fn for_database(db_type: &DatabaseType, requested_max_rows: usize) -> Self {
        let max_rows = requested_max_rows.max(1).min(match db_type {
            DatabaseType::SqlServer => MAX_SQLSERVER_INSERT_ROWS,
            DatabaseType::Oracle => MAX_ORACLE_INSERT_ALL_ROWS,
            _ => usize::MAX,
        });
        let target_sql_bytes = match db_type {
            DatabaseType::CloudflareD1 => crate::db::cloudflare_d1::MAX_SQL_STATEMENT_BYTES,
            _ => MAX_TRANSFER_WRITE_SQL_BYTES,
        };
        Self { max_rows, target_sql_bytes, hard_sql_bytes: None }
    }

    pub(crate) fn with_hard_sql_bytes(mut self, hard_sql_bytes: Option<usize>) -> Self {
        self.hard_sql_bytes = hard_sql_bytes;
        self
    }
}

#[derive(Debug, Clone, Serialize, Deserialize, Default, PartialEq)]
#[serde(rename_all = "camelCase")]
pub enum TransferMode {
    #[default]
    Append,
    Overwrite,
    Upsert,
}

#[derive(Debug, Clone, Serialize, Deserialize, Default, PartialEq)]
#[serde(rename_all = "camelCase")]
pub enum TransferTableNameCase {
    #[default]
    Preserve,
    Lower,
    Upper,
}

#[derive(Debug, Clone, Serialize, Deserialize, Default, PartialEq)]
#[serde(rename_all = "camelCase")]
pub enum TransferOwnershipPolicy {
    #[default]
    Preserve,
    Skip,
    ReassignMissing,
}

#[derive(Debug, Clone, Copy, Serialize, Deserialize, Default, PartialEq, Eq)]
#[serde(rename_all = "camelCase")]
pub enum TransferContent {
    #[default]
    StructureAndData,
    StructureOnly,
    DataOnly,
}

#[derive(Debug, Clone, Copy, Serialize, Deserialize, Default, PartialEq, Eq, Hash)]
#[serde(rename_all = "SCREAMING_SNAKE_CASE")]
pub enum TransferObjectKind {
    #[default]
    Table,
    View,
    MaterializedView,
    Procedure,
    Function,
    Trigger,
    Sequence,
    Event,
}

#[derive(Debug, Clone, Serialize, Deserialize, Default, PartialEq)]
#[serde(rename_all = "camelCase")]
pub struct TransferObjectSelection {
    pub object_type: TransferObjectKind,
    pub names: Vec<String>,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum TransferObjectFamily {
    Mysql,
    Postgres,
    Oracle,
    SqlServer,
}

pub fn transfer_object_family(db_type: &DatabaseType) -> Option<TransferObjectFamily> {
    match db_type {
        DatabaseType::Mysql => Some(TransferObjectFamily::Mysql),
        DatabaseType::Postgres
        | DatabaseType::Kingbase
        | DatabaseType::Gaussdb
        | DatabaseType::Kwdb
        | DatabaseType::OpenGauss => Some(TransferObjectFamily::Postgres),
        DatabaseType::Oracle | DatabaseType::Dameng | DatabaseType::OceanbaseOracle => {
            Some(TransferObjectFamily::Oracle)
        }
        DatabaseType::SqlServer => Some(TransferObjectFamily::SqlServer),
        _ => None,
    }
}

pub fn is_same_transfer_family(a: &DatabaseType, b: &DatabaseType) -> bool {
    match (transfer_object_family(a), transfer_object_family(b)) {
        (Some(fa), Some(fb)) => fa == fb,
        _ => false,
    }
}

pub fn transfer_object_kinds_for_family(family: &TransferObjectFamily) -> Vec<TransferObjectKind> {
    use TransferObjectKind::*;
    match family {
        TransferObjectFamily::Mysql => vec![Table, View, Procedure, Function, Trigger, Event],
        TransferObjectFamily::Postgres => vec![Table, View, MaterializedView, Procedure, Function, Trigger, Sequence],
        TransferObjectFamily::Oracle => vec![Table, View, MaterializedView, Procedure, Function, Trigger, Sequence],
        TransferObjectFamily::SqlServer => vec![Table, View, Procedure, Function, Trigger, Sequence],
    }
}

pub fn transfer_object_kinds(db_type: &DatabaseType) -> Vec<TransferObjectKind> {
    match transfer_object_family(db_type) {
        Some(family) => transfer_object_kinds_for_family(&family),
        None => Vec::new(),
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct TransferRequest {
    pub transfer_id: String,
    pub source_connection_id: String,
    pub source_database: String,
    pub source_schema: String,
    pub source_catalog: Option<String>,
    pub target_connection_id: String,
    pub target_database: String,
    pub target_schema: String,
    pub target_catalog: Option<String>,
    pub tables: Vec<String>,
    pub create_table: bool,
    #[serde(default)]
    pub content: TransferContent,
    #[serde(default)]
    pub objects: Vec<TransferObjectSelection>,
    #[serde(default)]
    pub mode: TransferMode,
    #[serde(default)]
    pub target_table_name_case: TransferTableNameCase,
    #[serde(default)]
    pub ownership_policy: TransferOwnershipPolicy,
    pub batch_size: usize,
}

#[derive(Debug, Clone, Serialize)]
#[serde(rename_all = "camelCase")]
pub struct TransferOwnershipPreview {
    pub missing_owners: Vec<String>,
    pub target_owner: String,
}

impl TransferRequest {
    pub fn target_table_name(&self, source_table: &str) -> String {
        match self.target_table_name_case {
            TransferTableNameCase::Preserve => source_table.to_string(),
            TransferTableNameCase::Lower => source_table.to_lowercase(),
            TransferTableNameCase::Upper => source_table.to_uppercase(),
        }
    }
}

#[derive(Debug, Clone, Serialize)]
#[serde(rename_all = "camelCase")]
pub struct TransferProgress {
    pub transfer_id: String,
    pub table: String,
    pub table_index: usize,
    pub total_tables: usize,
    pub rows_transferred: u64,
    pub total_rows: Option<u64>,
    pub status: TransferStatus,
    pub error: Option<String>,
    pub terminal: bool,
}

#[derive(Debug, Clone, Serialize)]
#[serde(rename_all = "camelCase")]
pub enum TransferStatus {
    Running,
    TableDone,
    Done,
    Error,
    Cancelled,
}

pub fn quote_identifier(name: &str, db_type: &DatabaseType) -> String {
    quote_transfer_identifier(name, db_type)
}

fn quote_identifier_with_identifier_quote(
    name: &str,
    db_type: &DatabaseType,
    identifier_quote: Option<&str>,
) -> String {
    crate::sql_dialect::quote_table_data_identifier(Some(*db_type), name, identifier_quote)
}

/// Resolve an optional catalog for external-catalog routing in the transfer
/// pipeline.  Returns `Some(catalog)` only when:
///   - the catalog is non-empty and not a built-in catalog name, AND
///   - the database type is Doris/StarRocks, or MySQL (StarRocks/Doris are often
///     saved as `db_type=mysql` with a matching `driver_profile`; the transfer UI
///     only sends `sourceCatalog`/`targetCatalog` for catalog-capable connections).
///
/// Built-in catalogs: Doris `internal`, StarRocks `default_catalog`. Prefer
/// [`resolve_external_transfer_catalog_for_config`] when a full connection
/// config is available (also matches `driver_profile=starrocks|doris`).
pub fn resolve_external_transfer_catalog<'a>(catalog: Option<&'a str>, db_type: &DatabaseType) -> Option<&'a str> {
    let catalog = normalize_external_catalog_name(catalog)?;
    match db_type {
        DatabaseType::Doris | DatabaseType::StarRocks | DatabaseType::Mysql => Some(catalog),
        _ => None,
    }
}

/// Like [`resolve_external_transfer_catalog`], but also treats MySQL connections
/// with a Doris/StarRocks `driver_profile` as catalog-capable.
pub fn resolve_external_transfer_catalog_for_config<'a>(
    catalog: Option<&'a str>,
    config: &crate::models::connection::ConnectionConfig,
) -> Option<&'a str> {
    let catalog = normalize_external_catalog_name(catalog)?;
    if crate::schema::is_doris_family_catalog_capable_config(config) {
        Some(catalog)
    } else {
        None
    }
}

fn normalize_external_catalog_name(catalog: Option<&str>) -> Option<&str> {
    let catalog = catalog?.trim();
    if catalog.is_empty() || catalog.eq_ignore_ascii_case("internal") || catalog.eq_ignore_ascii_case("default_catalog")
    {
        return None;
    }
    Some(catalog)
}

/// Create (or reuse) a transfer pool for the given connection/database/catalog.
///
/// For Doris/StarRocks external catalogs the pool is created with
/// `catalog=<name>` in the connection URL params so mysql_async runs
/// `SET catalog` **before** `USE <database>` during setup. The handshake does
/// not send the external database name (mysql_async strips the path when a
/// catalog is present), which is what previously caused `Unknown database`.
pub async fn ensure_transfer_pool(
    state: &AppState,
    connection_id: &str,
    database: &str,
    catalog: Option<&str>,
) -> Result<String, String> {
    let config = {
        let configs = state.configs.read().await;
        configs.get(connection_id).cloned().ok_or_else(|| format!("Connection config not found: {connection_id}"))?
    };
    if let Some(catalog) = resolve_external_transfer_catalog_for_config(catalog, &config) {
        // SET catalog first, then USE <database> so session has both catalog and
        // database selected — StarRocks rejects unqualified analysis with
        // "No database selected" when only SET catalog ran.
        state.get_or_create_pool_with_catalog(connection_id, Some(database), Some(catalog)).await
    } else {
        state.get_or_create_pool(connection_id, Some(database)).await
    }
}

pub fn qualified_table(table: &str, schema: &str, db_type: &DatabaseType, catalog: Option<&str>) -> String {
    // Only use 3-part catalog-qualified names for Doris/StarRocks external catalogs.
    let effective_catalog = resolve_external_transfer_catalog(catalog, db_type);
    qualified_transfer_table(table, schema, db_type, effective_catalog)
}

fn qualified_table_with_identifier_quote(
    table: &str,
    schema: &str,
    db_type: &DatabaseType,
    catalog: Option<&str>,
    identifier_quote: Option<&str>,
) -> String {
    if crate::sql_dialect::uses_connection_identifier_quote(Some(*db_type), identifier_quote) {
        crate::sql_dialect::table_data_qualified_table_name(
            Some(*db_type),
            (!schema.trim().is_empty()).then_some(schema),
            table,
            identifier_quote,
        )
    } else {
        qualified_table(table, schema, db_type, catalog)
    }
}

pub fn validate_transfer_target_table_names(request: &TransferRequest) -> Result<(), String> {
    let mut targets: HashMap<String, String> = HashMap::new();
    for source_table in &request.tables {
        let target_table = request.target_table_name(source_table);
        if let Some(first_source) = targets.insert(target_table.clone(), source_table.clone()) {
            return Err(format!(
                "Target table name collision after case conversion: '{first_source}' and '{source_table}' both map to '{target_table}'"
            ));
        }
    }
    Ok(())
}

/// Kinds that may be transferred between different database families.
/// Only DDL shapes that can be mechanically rewritten are allowed:
/// views (CREATE ... VIEW ... AS SELECT) and sequences (CREATE SEQUENCE).
/// Sequences additionally require both sides to support the type (MySQL does not).
/// Cross-family transfer is only supported between the MySQL, SQL Server and
/// Oracle/Dameng families; the Postgres family is not a validated source or
/// target for the cross-family DDL pipeline (the executor rejects it).
pub fn cross_family_transferable_object_kinds(source: &DatabaseType, target: &DatabaseType) -> Vec<TransferObjectKind> {
    use TransferObjectKind::*;
    if is_same_transfer_family(source, target) {
        return transfer_object_kinds(source);
    }
    // Narrow the matrix to validated directions: MySQL, SQL Server and
    // Oracle/Dameng may act as either side. Postgres (and anything else) is
    // excluded — the executor rejects Postgres sources and no dialect-aware
    // conversion is validated for it.
    let family_supported = |db_type: &DatabaseType| {
        matches!(
            transfer_object_family(db_type),
            Some(TransferObjectFamily::Mysql)
                | Some(TransferObjectFamily::SqlServer)
                | Some(TransferObjectFamily::Oracle)
        )
    };
    if !family_supported(source) || !family_supported(target) {
        return Vec::new();
    }
    // Cross-family VIEW transfer is disabled: convert_cross_family_object_ddl
    // only rewrites the DDL wrapper, identifier quoting and schema qualifiers —
    // it does not translate the view query body, so source-specific constructs
    // (IFNULL, TOP, GETDATE, …) would execute unchanged on an incompatible
    // target. Only sequences are allowed: their CREATE SEQUENCE statements are
    // plain DDL (no query body) and the small set of dialect differences
    // (AS <type>, NOCYCLE/NOCACHE) is converted and tested.
    let source_kinds = transfer_object_kinds(source);
    let target_kinds = transfer_object_kinds(target);
    let mut allowed = Vec::new();
    if source_kinds.contains(&Sequence) && target_kinds.contains(&Sequence) {
        allowed.push(Sequence);
    }
    allowed
}

/// Rewrites a source DDL fragment to the target family's quoting style and
/// schema qualifier. Prefix normalization (DEFINER/ALGORITHM/FORCE/WITH
/// SCHEMABINDING/AS <type>) is applied per source family.
pub fn convert_cross_family_object_ddl(
    source_family: &TransferObjectFamily,
    target_family: &TransferObjectFamily,
    kind: &TransferObjectKind,
    source_schema: &str,
    target_schema: &str,
    ddl: &str,
) -> String {
    let mut sql = ddl.trim().to_string();
    match kind {
        TransferObjectKind::View => match source_family {
            TransferObjectFamily::Mysql => {
                sql = strip_mysql_definer(&sql);
                sql = strip_sql_view_prefix(&sql);
            }
            TransferObjectFamily::Oracle => {
                sql = strip_sql_view_prefix(&sql);
            }
            TransferObjectFamily::SqlServer => {
                sql = strip_sqlserver_view_with_clause(&sql);
            }
            _ => {}
        },
        TransferObjectKind::Sequence => match source_family {
            TransferObjectFamily::SqlServer => {
                sql = strip_sqlserver_sequence_as_type(&sql);
            }
            TransferObjectFamily::Oracle if target_family == &TransferObjectFamily::SqlServer => {
                sql = sql.replace("NOCYCLE", "NO CYCLE").replace("NOCACHE", "NO CACHE");
            }
            _ => {}
        },
        _ => {}
    }
    // Mask string literals and comments before any identifier/schema
    // rewrite, then restore them afterwards: regexes that re-quote
    // identifiers must never touch text inside strings or comments. MySQL
    // double-quoted text is a string literal (unless ANSI_QUOTES is on).
    let (masked, restores) = protect_sql_literals(&sql, matches!(source_family, TransferObjectFamily::Mysql));
    sql = rewrite_identifiers_to_target(&masked, target_family);
    if !source_schema.is_empty() && !target_schema.is_empty() && !source_schema.eq_ignore_ascii_case(target_schema) {
        sql = rewrite_cross_family_schema_qualifier(&sql, target_family, source_schema, target_schema);
    }
    if kind == &TransferObjectKind::View {
        sql = qualify_cross_family_view_target(&sql, target_family, target_schema);
    }
    for (placeholder, original) in restores {
        sql = sql.replace(&placeholder, &original);
    }
    sql
}

/// Locates string literals and comments in SQL: single-quoted strings
/// (with `''` and backslash escapes), MySQL double-quoted strings when
/// `double_quote_is_string` is set, `--`/`#` line comments and `/* */`
/// block comments. Returns byte ranges `(start, end)` of those spans.
fn sql_non_code_spans_with_mysql_identifiers(
    sql: &str,
    double_quote_is_string: bool,
    backtick_is_identifier: bool,
) -> Vec<(usize, usize)> {
    let bytes = sql.as_bytes();
    let mut spans = Vec::new();
    let mut i = 0;
    while i < bytes.len() {
        let b = bytes[i];
        let starts_non_code = match b {
            b'\'' => true,
            b'"' if double_quote_is_string => true,
            b'`' if backtick_is_identifier => true,
            b'-' if i + 1 < bytes.len() && bytes[i + 1] == b'-' => true,
            b'#' => true, // MySQL line comment
            b'/' if i + 1 < bytes.len() && bytes[i + 1] == b'*' => true,
            _ => false,
        };
        if !starts_non_code {
            i += 1;
            continue;
        }
        let start = i;
        i = match b {
            b'\'' | b'"' | b'`' => {
                i += 1;
                while i < bytes.len() {
                    if bytes[i] == b'\\' && i + 1 < bytes.len() {
                        i += 2; // backslash escape (MySQL style)
                        continue;
                    }
                    if bytes[i] == b && i + 1 < bytes.len() && bytes[i + 1] == b {
                        i += 2; // '' / "" doubled quote
                        continue;
                    }
                    if bytes[i] == b {
                        i += 1;
                        break;
                    }
                    i += 1;
                }
                i
            }
            b'-' | b'#' => {
                while i < bytes.len() && bytes[i] != b'\n' {
                    i += 1;
                }
                i
            }
            _ => {
                i += 2; // /* ... */
                while i + 1 < bytes.len() && !(bytes[i] == b'*' && bytes[i + 1] == b'/') {
                    i += 1;
                }
                (i + 2).min(bytes.len())
            }
        };
        spans.push((start, i));
    }
    spans
}

fn sql_non_code_spans(sql: &str, double_quote_is_string: bool) -> Vec<(usize, usize)> {
    sql_non_code_spans_with_mysql_identifiers(sql, double_quote_is_string, false)
}

/// Applies `f` to every code span of `sql`; string literals and comments
/// (see `sql_non_code_spans`) pass through verbatim so rewrites never touch
/// text inside them.
fn map_sql_code_spans<F>(sql: &str, double_quote_is_string: bool, mut f: F) -> String
where
    F: FnMut(&str) -> String,
{
    let spans = sql_non_code_spans(sql, double_quote_is_string);
    let mut out = String::with_capacity(sql.len());
    let mut prev = 0;
    for (start, end) in spans {
        if start > prev {
            out.push_str(&f(&sql[prev..start]));
        }
        out.push_str(&sql[start..end]);
        prev = end;
    }
    if prev < sql.len() {
        out.push_str(&f(&sql[prev..]));
    }
    out
}

fn map_mysql_ddl_code_spans<F>(sql: &str, mut f: F) -> String
where
    F: FnMut(&str) -> String,
{
    let spans = sql_non_code_spans_with_mysql_identifiers(sql, true, true);
    let mut out = String::with_capacity(sql.len());
    let mut prev = 0;
    for (start, end) in spans {
        if start > prev {
            out.push_str(&f(&sql[prev..start]));
        }
        out.push_str(&sql[start..end]);
        prev = end;
    }
    if prev < sql.len() {
        out.push_str(&f(&sql[prev..]));
    }
    out
}

/// Masks string literals and comments with placeholders so subsequent regex
/// rewrites cannot touch them, and returns the restore map to swap the
/// original text back afterwards.
fn protect_sql_literals(sql: &str, double_quote_is_string: bool) -> (String, Vec<(String, String)>) {
    let spans = sql_non_code_spans(sql, double_quote_is_string);
    let mut out = String::with_capacity(sql.len());
    let mut restores = Vec::new();
    let mut prev = 0;
    for (start, end) in spans {
        if start > prev {
            out.push_str(&sql[prev..start]);
        }
        let placeholder = format!("__DBX_LIT_{}__", restores.len());
        out.push_str(&placeholder);
        restores.push((placeholder, sql[start..end].to_string()));
        prev = end;
    }
    if prev < sql.len() {
        out.push_str(&sql[prev..]);
    }
    (out, restores)
}

/// Aligns a cross-family view DDL with the target schema: the `CREATE VIEW`
/// target and bare table references in the body (`FROM`/`JOIN`/`INTO`/`UPDATE`)
/// are qualified with the target schema, matching how table transfer creates
/// tables (`"schema"."table"`). References that already carry a prefix are left
/// untouched. String literals and comments are preserved verbatim (see
/// `map_sql_code_spans`).
fn qualify_cross_family_view_target(sql: &str, target_family: &TransferObjectFamily, target_schema: &str) -> String {
    if target_schema.is_empty() {
        return sql.to_string();
    }
    let (open, close) = match target_family {
        TransferObjectFamily::Mysql => ("`", "`"),
        TransferObjectFamily::SqlServer => ("[", "]"),
        TransferObjectFamily::Oracle => ("\"", "\""),
        _ => return sql.to_string(),
    };
    let qo = regex::escape(open);
    let qc = regex::escape(close);
    // Identifiers may contain any characters (including CJK) except the
    // closing quote of the target dialect, since every identifier has been
    // normalized to the target quoting style by this point.
    let ident = match target_family {
        TransferObjectFamily::Mysql => r#"[^`]+"#,
        TransferObjectFamily::SqlServer => r#"[^\]]+"#,
        TransferObjectFamily::Oracle => r#"[^"]+"#,
        _ => "[A-Za-z_][A-Za-z0-9_]*",
    };
    let create_re = Regex::new(&format!(r"(?i)\bCREATE\s+VIEW\s+(?:{qo}({ident}){qc}\.)?{qo}({ident}){qc}")).unwrap();
    let mut out = create_re
        .replace_all(sql, |caps: &regex::Captures| {
            let name = &caps[2];
            if matches!(caps.get(1), Some(m) if !m.as_str().is_empty()) {
                caps[0].to_string()
            } else {
                format!("CREATE VIEW {open}{target_schema}{close}.{open}{name}{close}")
            }
        })
        .to_string();
    // bare references after FROM/JOIN/INTO/UPDATE/TABLE get the schema prefix;
    // already-prefixed references (group 1) stay as-is
    let ref_re =
        Regex::new(&format!(r"(?i)\b(from|join|into|update|table)\s+(?:{qo}({ident}){qc}\.)?{qo}({ident}){qc}"))
            .unwrap();
    out = ref_re
        .replace_all(&out, |caps: &regex::Captures| {
            let name = &caps[3];
            if matches!(caps.get(2), Some(m) if !m.as_str().is_empty()) {
                caps[0].to_string()
            } else {
                format!("{} {open}{target_schema}{close}.{open}{name}{close}", &caps[1])
            }
        })
        .to_string();
    out
}

/// Collapses `CREATE [ALGORITHM=..] [DEFINER=..] [SQL SECURITY ..] VIEW`,
/// `CREATE OR REPLACE [FORCE] [NONEDITIONABLE] VIEW` and plain `CREATE VIEW`
/// into a bare `CREATE VIEW` prefix usable on every target family.
fn strip_sql_view_prefix(sql: &str) -> String {
    if let Some(pos) = sql.find(" VIEW ") {
        let head = &sql[..pos];
        if head.trim_start().starts_with("CREATE") {
            return format!("CREATE VIEW{}", &sql[pos + 5..]);
        }
    }
    sql.to_string()
}

/// Removes `WITH SCHEMABINDING` between the view name and `AS` in SQL Server
/// view definitions.
fn strip_sqlserver_view_with_clause(sql: &str) -> String {
    let re = Regex::new(r"(?i)\s+WITH\s+SCHEMABINDING\s+").unwrap();
    map_sql_code_spans(sql, false, |code| re.replace_all(code, " ").to_string())
}

/// Removes the ` AS <type>` clause from a SQL Server CREATE SEQUENCE so the
/// DDL fits Dameng/Oracle sequence syntax.
fn strip_sqlserver_sequence_as_type(sql: &str) -> String {
    let re =
        Regex::new(r"(?i)\s+AS\s+(?:BIGINT|INT|SMALLINT|TINYINT|DECIMAL\s*\([^)]*\)|NUMERIC\s*\([^)]*\))\s+").unwrap();
    map_sql_code_spans(sql, false, |code| re.replace_all(code, " ").to_string())
}

/// Rewrites backtick / double-quote / bracket identifier quoting to the
/// target family's style. Only identifiers in code positions are rewritten:
/// string literals and comments are preserved verbatim (see
/// `map_sql_code_spans`). The source family decides whether double-quoted
/// text is a string literal (MySQL, unless ANSI_QUOTES is on) or an
/// identifier (SQL Server / Oracle).
fn rewrite_identifiers_to_target(sql: &str, target: &TransferObjectFamily) -> String {
    let (open, close, pattern) = match target {
        TransferObjectFamily::Mysql => ("`", "`", r#""([^"]+)"|\[([^\]]+)\]"#),
        TransferObjectFamily::SqlServer => ("[", "]", r#"`([^`]+)`|"([^"]+)""#),
        TransferObjectFamily::Oracle => ("\"", "\"", r#"`([^`]+)`|\[([^\]]+)\]"#),
        _ => return sql.to_string(),
    };
    let re = Regex::new(pattern).unwrap();
    re.replace_all(sql, |caps: &regex::Captures| {
        let name = caps.get(1).map(|m| m.as_str()).or_else(|| caps.get(2).map(|m| m.as_str())).unwrap_or("");
        format!("{open}{name}{close}")
    })
    .to_string()
}

/// Rewrites `{quote}{source_schema}{quote}.` qualifiers to the target schema
/// in the target family's quoting style.
fn rewrite_cross_family_schema_qualifier(
    sql: &str,
    target: &TransferObjectFamily,
    source_schema: &str,
    target_schema: &str,
) -> String {
    let (open, close) = match target {
        TransferObjectFamily::Mysql => ("`", "`"),
        TransferObjectFamily::SqlServer => ("[", "]"),
        TransferObjectFamily::Oracle => ("\"", "\""),
        _ => return sql.to_string(),
    };
    let source = format!("{open}{}{close}.", regex::escape(source_schema));
    let target = format!("{open}{target_schema}{close}.");
    sql.replace(&source, &target)
}

pub fn validate_transfer_request(request: &TransferRequest) -> Result<(), String> {
    validate_transfer_target_table_names(request)?;
    if matches!(request.content, TransferContent::DataOnly) && !request.objects.is_empty() {
        return Err("仅数据模式不传输非表对象".to_string());
    }
    for selection in &request.objects {
        if selection.names.is_empty() {
            return Err(format!("Object selection for {:?} is empty", selection.object_type));
        }
        for name in &selection.names {
            if name.trim().is_empty() || name.contains('\0') {
                return Err(format!("Invalid object name: {name:?}"));
            }
        }
    }
    Ok(())
}

#[derive(Debug, Clone, PartialEq, Eq)]
struct ResolvedTransferTargetTable {
    name: String,
    preexisting: bool,
}

fn json_scalar_to_string(value: &serde_json::Value) -> Option<String> {
    match value {
        serde_json::Value::String(value) => Some(value.clone()),
        serde_json::Value::Number(value) => Some(value.to_string()),
        serde_json::Value::Bool(value) => Some(value.to_string()),
        _ => None,
    }
}

fn mysql_lower_case_table_names_from_result(result: &db::QueryResult) -> Option<u8> {
    let row = result.rows.first()?;
    row.get(1).or_else(|| row.first()).and_then(json_scalar_to_string)?.trim().parse::<u8>().ok()
}

async fn target_table_lookup_is_case_insensitive(
    state: &AppState,
    target_pool_key: &str,
    target_db_type: &DatabaseType,
) -> bool {
    if !matches!(target_db_type, DatabaseType::Mysql) {
        return false;
    }

    let result = match execute_on_pool(state, target_pool_key, "SHOW VARIABLES LIKE 'lower_case_table_names'").await {
        Ok(result) => result,
        Err(error) => {
            log::debug!("[transfer] failed to read MySQL lower_case_table_names: {error}");
            return false;
        }
    };

    // MySQL lower_case_table_names=1/2 means table lookup is case-insensitive.
    // Prefer the metadata name so generated INSERT/TRUNCATE SQL keeps the target
    // table's declared case instead of the source-derived request case.
    mysql_lower_case_table_names_from_result(&result).is_some_and(|value| value != 0)
}

fn existing_transfer_target_table_name(
    requested_name: &str,
    tables: &[db::TableInfo],
    allow_case_insensitive_match: bool,
) -> Option<String> {
    if let Some(table) = tables.iter().find(|table| table.name == requested_name) {
        return Some(table.name.clone());
    }
    if !allow_case_insensitive_match {
        return None;
    }
    tables.iter().find(|table| table.name.eq_ignore_ascii_case(requested_name)).map(|table| table.name.clone())
}

async fn resolve_transfer_target_table_name(
    state: &AppState,
    request: &TransferRequest,
    source_table: &str,
    target_pool_key: &str,
    target_db_type: &DatabaseType,
    _source_catalog: Option<&str>,
    target_catalog: Option<&str>,
) -> ResolvedTransferTargetTable {
    let requested_name = request.target_table_name(source_table);
    if is_mongodb_transfer_type(target_db_type) {
        return ResolvedTransferTargetTable { name: requested_name, preexisting: false };
    }

    let allow_case_insensitive_match =
        target_table_lookup_is_case_insensitive(state, target_pool_key, target_db_type).await;

    // Route through the catalog-aware path when targeting an external
    // Doris/StarRocks catalog — otherwise the lookup runs against the
    // default / internal catalog and can miss or misidentify the table.
    let tables = if let Some(catalog) = resolve_external_transfer_catalog(target_catalog, target_db_type) {
        crate::schema::list_doris_catalog_tables_core(
            state,
            &request.target_connection_id,
            catalog,
            &request.target_database,
            Some(&requested_name),
            Some(TRANSFER_TARGET_TABLE_LOOKUP_LIMIT),
            None,
            None,
            None,
        )
        .await
        .unwrap_or_else(|error| {
            log::debug!("[transfer] failed to resolve target table metadata for {requested_name} in catalog '{catalog}': {error}");
            Vec::new()
        })
    } else {
        crate::schema::list_tables_core(
            state,
            &request.target_connection_id,
            &request.target_database,
            &request.target_schema,
            Some(&requested_name),
            Some(TRANSFER_TARGET_TABLE_LOOKUP_LIMIT),
            None,
            None,
            None,
        )
        .await
        .unwrap_or_else(|error| {
            log::debug!("[transfer] failed to resolve target table metadata for {requested_name}: {error}");
            Vec::new()
        })
    };

    if let Some(existing_name) =
        existing_transfer_target_table_name(&requested_name, &tables, allow_case_insensitive_match)
    {
        ResolvedTransferTargetTable { name: existing_name, preexisting: true }
    } else {
        ResolvedTransferTargetTable { name: requested_name, preexisting: false }
    }
}

fn quote_string_literal(value: &str) -> String {
    format!("'{}'", value.replace('\'', "''"))
}

/// Returns a SQL statement selecting 1 row when `name` exists in `schema`
/// on the target side; None-kind support per family mirrors
/// `transfer_object_kinds`.
pub fn target_object_exists_sql(
    db_type: &DatabaseType,
    schema: &str,
    name: &str,
    kind: &TransferObjectKind,
) -> Result<String, String> {
    let schema = quote_string_literal(schema);
    let name = quote_string_literal(name);
    let q = |literal: &str| literal.to_string();
    let sql = match (transfer_object_family(db_type), kind) {
        (Some(TransferObjectFamily::Mysql), TransferObjectKind::Table | TransferObjectKind::View) => format!(
            "SELECT 1 FROM information_schema.TABLES WHERE TABLE_SCHEMA = {schema} AND TABLE_NAME = {name} \
             AND TABLE_TYPE {} 'VIEW'",
            if matches!(kind, TransferObjectKind::View) { "=" } else { "<>" }
        ),
        (Some(TransferObjectFamily::Mysql), TransferObjectKind::Procedure | TransferObjectKind::Function) => format!(
            "SELECT 1 FROM information_schema.ROUTINES WHERE ROUTINE_SCHEMA = {schema} AND ROUTINE_NAME = {name} \
             AND ROUTINE_TYPE = {}",
            q(if matches!(kind, TransferObjectKind::Procedure) { "'PROCEDURE'" } else { "'FUNCTION'" })
        ),
        (Some(TransferObjectFamily::Mysql), TransferObjectKind::Trigger) => format!(
            "SELECT 1 FROM information_schema.TRIGGERS WHERE TRIGGER_SCHEMA = {schema} AND TRIGGER_NAME = {name}"
        ),
        (Some(TransferObjectFamily::Mysql), TransferObjectKind::Event) => {
            format!("SELECT 1 FROM information_schema.EVENTS WHERE EVENT_SCHEMA = {schema} AND EVENT_NAME = {name}")
        }
        (Some(TransferObjectFamily::Postgres), TransferObjectKind::View | TransferObjectKind::MaterializedView) => {
            format!(
                "SELECT 1 FROM pg_catalog.pg_class c JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace \
             WHERE n.nspname = {schema} AND c.relname = {name} AND c.relkind {}",
                if matches!(kind, TransferObjectKind::MaterializedView) { "= 'm'" } else { "= 'v'" }
            )
        }
        (Some(TransferObjectFamily::Postgres), TransferObjectKind::Table) => format!(
            "SELECT 1 FROM pg_catalog.pg_class c JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace \
             WHERE n.nspname = {schema} AND c.relname = {name} AND c.relkind = 'r'"
        ),
        (Some(TransferObjectFamily::Postgres), TransferObjectKind::Procedure | TransferObjectKind::Function) => {
            format!(
                "SELECT 1 FROM pg_catalog.pg_proc p JOIN pg_catalog.pg_namespace n ON n.oid = p.pronamespace \
             WHERE n.nspname = {schema} AND p.proname = {name}"
            )
        }
        (Some(TransferObjectFamily::Postgres), TransferObjectKind::Sequence) => format!(
            "SELECT 1 FROM pg_catalog.pg_class c JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace \
             WHERE n.nspname = {schema} AND c.relname = {name} AND c.relkind = 'S'"
        ),
        (Some(TransferObjectFamily::Postgres), TransferObjectKind::Trigger) => format!(
            "SELECT 1 FROM pg_catalog.pg_trigger t JOIN pg_catalog.pg_class c ON c.oid = t.tgrelid \
             JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace \
             WHERE n.nspname = {schema} AND t.tgname = {name} AND NOT t.tgisinternal"
        ),
        (
            Some(TransferObjectFamily::Oracle),
            TransferObjectKind::View
            | TransferObjectKind::MaterializedView
            | TransferObjectKind::Procedure
            | TransferObjectKind::Function
            | TransferObjectKind::Trigger
            | TransferObjectKind::Sequence,
        ) => format!(
            "SELECT 1 FROM ALL_OBJECTS WHERE OWNER = {schema} AND OBJECT_NAME = {name} AND OBJECT_TYPE = {}",
            q(match kind {
                TransferObjectKind::View => "'VIEW'",
                TransferObjectKind::MaterializedView => "'MATERIALIZED VIEW'",
                TransferObjectKind::Procedure => "'PROCEDURE'",
                TransferObjectKind::Function => "'FUNCTION'",
                TransferObjectKind::Trigger => "'TRIGGER'",
                _ => "'SEQUENCE'",
            })
        ),
        (
            Some(TransferObjectFamily::SqlServer),
            TransferObjectKind::Table
            | TransferObjectKind::View
            | TransferObjectKind::Procedure
            | TransferObjectKind::Function
            | TransferObjectKind::Trigger
            | TransferObjectKind::Sequence,
        ) => format!(
            "SELECT 1 FROM sys.objects o JOIN sys.schemas s ON s.schema_id = o.schema_id \
             WHERE s.name = {schema} AND o.name = {name} AND o.type IN ({})",
            q(match kind {
                TransferObjectKind::Table => "'U'",
                TransferObjectKind::View => "'V'",
                TransferObjectKind::Procedure => "'P'",
                TransferObjectKind::Function => "'FN','IF','TF','FS','FT'",
                TransferObjectKind::Trigger => "'TR'",
                _ => "'SO'",
            })
        ),
        _ => return Err(format!("Object existence check not supported for {:?} {:?}", db_type, kind)),
    };
    Ok(sql)
}

/// Remove `DEFINER=`user`@`host`` tokens from MySQL DDL (they are not
/// transferable and frequently reference accounts that don't exist on target).
pub fn strip_mysql_definer(ddl: &str) -> String {
    let re = Regex::new(r"(?i)\bDEFINER\s*=\s*`[^`]*`@`[^`]*`\s*").unwrap();
    re.replace_all(ddl, "").to_string()
}

/// Rewrite backtick-qualified `schema`.`name` references from `source_schema`
/// to `target_schema` in MySQL DDL.
pub fn rewrite_mysql_schema_qualifier(ddl: &str, source_schema: &str, target_schema: &str) -> String {
    if source_schema == target_schema || source_schema.is_empty() {
        return ddl.to_string();
    }
    let re = Regex::new(&format!(r"`{}`\.", regex::escape(source_schema))).unwrap();
    re.replace_all(ddl, &format!("`{}`.", target_schema)).to_string()
}

pub fn mysql_trigger_ddl(
    schema: &str,
    name: &str,
    timing: &str,
    manipulation: &str,
    table: &str,
    statement: &str,
) -> String {
    format!(
        "CREATE TRIGGER `{name}` {timing} {manipulation} ON `{schema}`.`{table}` FOR EACH ROW {statement}",
        name = name,
        timing = timing,
        manipulation = manipulation,
        schema = schema,
        table = table,
        statement = statement.trim()
    )
}

pub fn mysql_event_ddl(_schema: &str, name: &str, status: &str, schedule: &str, body: &str) -> String {
    format!(
        "CREATE EVENT `{name}` ON SCHEDULE {schedule} {status} DO {body}",
        name = name,
        schedule = schedule,
        status = status,
        body = body.trim()
    )
}

/// Builds the query that fetches DDL for one MySQL object.
/// - View/Procedure/Function → `SHOW CREATE ...`
/// - Trigger → information_schema.TRIGGERS row (timing/manipulation/table/
///   statement) via `mysql_trigger_ddl`.
/// - Event → information_schema.EVENTS row via `mysql_event_ddl`.
pub fn mysql_object_source_query(kind: &TransferObjectKind, database: &str, name: &str) -> Result<String, String> {
    let db = quote_string_literal(database);
    let n = quote_string_literal(name);
    let ddl = match kind {
        TransferObjectKind::View => format!("SHOW CREATE VIEW `{database}`.`{name}`"),
        TransferObjectKind::Procedure => format!("SHOW CREATE PROCEDURE `{database}`.`{name}`"),
        TransferObjectKind::Function => format!("SHOW CREATE FUNCTION `{database}`.`{name}`"),
        TransferObjectKind::Trigger => format!(
            "SELECT TRIGGER_NAME, ACTION_TIMING, EVENT_MANIPULATION, EVENT_OBJECT_TABLE, ACTION_STATEMENT \
             FROM information_schema.TRIGGERS WHERE TRIGGER_SCHEMA = {db} AND TRIGGER_NAME = {n}"
        ),
        TransferObjectKind::Event => format!(
            "SELECT EVENT_NAME, STATUS, EXECUTE_AT, INTERVAL_VALUE, INTERVAL_FIELD, EVENT_DEFINITION \
             FROM information_schema.EVENTS WHERE EVENT_SCHEMA = {db} AND EVENT_NAME = {n}"
        ),
        _ => return Err(format!("MySQL object source not supported for {:?}", kind)),
    };
    Ok(ddl)
}

/// Maps a MySQL DDL query result row to a single DDL string.
/// SHOW CREATE column index: view=1, routine=2 (same convention as
/// `schema::mysql_object_source_ddl_column_index`); triggers and events are
/// assembled from information_schema cells.
pub fn mysql_object_ddl_from_result(
    kind: &TransferObjectKind,
    database: &str,
    rows: &[Vec<serde_json::Value>],
) -> Result<String, String> {
    let row = rows.first().ok_or_else(|| format!("No rows returned for MySQL {:?} DDL", kind))?;
    let cell = |idx: usize| -> Result<&str, String> {
        row.get(idx)
            .and_then(|value| value.as_str())
            .ok_or_else(|| format!("Missing column {idx} in MySQL {:?} DDL result", kind))
    };
    match kind {
        TransferObjectKind::View => Ok(cell(1)?.to_string()),
        TransferObjectKind::Procedure | TransferObjectKind::Function => Ok(cell(2)?.to_string()),
        TransferObjectKind::Trigger => {
            let name = cell(0)?;
            let timing = cell(1)?;
            let manipulation = cell(2)?;
            let table = cell(3)?;
            let statement = cell(4)?;
            Ok(mysql_trigger_ddl(database, name, timing, manipulation, table, statement))
        }
        TransferObjectKind::Event => {
            let name = cell(0)?;
            let status = cell(1)?;
            let execute_at = cell(2)?;
            let interval_value = cell(3)?;
            let interval_field = cell(4)?;
            let body = cell(5)?;
            let schedule = if interval_value.is_empty() && interval_field.is_empty() {
                format!("AT {execute_at}")
            } else {
                format!("EVERY {interval_value} {interval_field}")
            };
            Ok(mysql_event_ddl(database, name, status, &schedule, body))
        }
        _ => Err(format!("MySQL object DDL extraction not supported for {:?}", kind)),
    }
}

pub fn oracle_object_source_query(kind: &TransferObjectKind, schema: &str, name: &str) -> Result<String, String> {
    let object_type = match kind {
        TransferObjectKind::View => "VIEW",
        TransferObjectKind::MaterializedView => "MATERIALIZED_VIEW",
        TransferObjectKind::Procedure => "PROCEDURE",
        TransferObjectKind::Function => "FUNCTION",
        TransferObjectKind::Trigger => "TRIGGER",
        TransferObjectKind::Sequence => "SEQUENCE",
        _ => return Err(format!("Oracle object source not supported for {:?}", kind)),
    };
    let name_lit = quote_string_literal(name);
    if schema.trim().is_empty() {
        Ok(format!("SELECT DBMS_METADATA.GET_DDL({}, {}) FROM DUAL", quote_string_literal(object_type), name_lit))
    } else {
        Ok(format!(
            "SELECT DBMS_METADATA.GET_DDL({}, {}, {}) FROM DUAL",
            quote_string_literal(object_type),
            name_lit,
            quote_string_literal(schema)
        ))
    }
}

/// Rewrite `"SCHEMA"."NAME"` occurrences in Oracle/DM metadata DDL from
/// source_schema to target_schema.
pub fn sqlserver_object_source_query(kind: &TransferObjectKind, schema: &str, name: &str) -> Result<String, String> {
    match kind {
        TransferObjectKind::View
        | TransferObjectKind::Procedure
        | TransferObjectKind::Function
        | TransferObjectKind::Trigger => {
            let object_type = match kind {
                TransferObjectKind::View => "'V'",
                TransferObjectKind::Procedure => "'P'",
                TransferObjectKind::Function => "'FN','IF','TF','FS','FT'",
                _ => "'TR'",
            };
            Ok(format!(
                "SELECT m.definition FROM sys.sql_modules m \
                 JOIN sys.objects o ON o.object_id = m.object_id \
                 JOIN sys.schemas s ON s.schema_id = o.schema_id \
                 WHERE s.name = {} AND o.name = {} AND o.type IN ({})",
                quote_string_literal(schema),
                quote_string_literal(name),
                object_type
            ))
        }
        TransferObjectKind::Sequence => Ok(format!(
            "SELECT CAST(seq.start_value AS NVARCHAR(50)), \
             CAST(seq.increment_value AS NVARCHAR(50)), \
             CAST(seq.minimum_value AS NVARCHAR(50)), \
             CAST(seq.maximum_value AS NVARCHAR(50)), \
             CASE WHEN seq.is_cycling = 1 THEN 'CYCLE' ELSE 'NO CYCLE' END, \
             CASE WHEN seq.is_cached = 1 THEN CAST(seq.cache_size AS NVARCHAR(50)) ELSE '0' END \
             FROM sys.sequences seq JOIN sys.schemas s ON s.schema_id = seq.schema_id \
             WHERE s.name = {} AND seq.name = {}",
            quote_string_literal(schema),
            quote_string_literal(name)
        )),
        _ => Err(format!("SQL Server object source not supported for {:?}", kind)),
    }
}

pub fn sqlserver_object_ddl_from_result(
    result: &db::QueryResult,
    schema: &str,
    name: &str,
    kind: &TransferObjectKind,
) -> Result<String, String> {
    let Some(row) = result.rows.first() else {
        return Err(format!("No DDL returned for SQL Server {kind:?} {name}"));
    };
    match kind {
        TransferObjectKind::View
        | TransferObjectKind::Procedure
        | TransferObjectKind::Function
        | TransferObjectKind::Trigger => row
            .first()
            .and_then(|v| v.as_str())
            .map(|s| s.to_string())
            .ok_or_else(|| format!("No DDL returned for SQL Server {kind:?} {name}")),
        TransferObjectKind::Sequence => {
            let cell = |i: usize| row.get(i).and_then(|v| v.as_str()).unwrap_or("");
            let start = cell(0);
            let increment = cell(1);
            let minimum = cell(2);
            let maximum = cell(3);
            let cycle = cell(4);
            let cache = cell(5);
            Ok(format!(
                "CREATE SEQUENCE [{}].[{}] START WITH {} INCREMENT BY {} MINVALUE {} MAXVALUE {} {} {}",
                schema,
                name,
                start,
                increment,
                minimum,
                maximum,
                cycle,
                if cache == "0" { "NO CACHE".to_string() } else { format!("CACHE {cache}") }
            ))
        }
        _ => Err(format!("SQL Server object DDL not supported for {:?}", kind)),
    }
}
pub fn rewrite_oracle_schema_qualifier(ddl: &str, source_schema: &str, target_schema: &str) -> String {
    if source_schema == target_schema || source_schema.is_empty() {
        return ddl.to_string();
    }
    let re = Regex::new(&format!(r#""{}"\."#, regex::escape(source_schema))).unwrap();
    re.replace_all(ddl, &format!("\"{target_schema}\".")).to_string()
}

pub(crate) fn quote_postgres_string_literal(value: &str) -> String {
    if !value.contains('\\') && !value.chars().any(|character| character.is_ascii_control()) {
        return quote_string_literal(value);
    }

    let mut escaped = String::with_capacity(value.len());
    for character in value.chars() {
        match character {
            '\\' => escaped.push_str("\\\\"),
            '\n' => escaped.push_str("\\n"),
            '\r' => escaped.push_str("\\r"),
            '\t' => escaped.push_str("\\t"),
            '\x08' => escaped.push_str("\\b"),
            '\x0c' => escaped.push_str("\\f"),
            '\'' => escaped.push_str("''"),
            character if character.is_ascii_control() => {
                const HEX: &[u8; 16] = b"0123456789ABCDEF";
                let byte = character as u8;
                escaped.push_str("\\x");
                escaped.push(HEX[(byte >> 4) as usize] as char);
                escaped.push(HEX[(byte & 0x0F) as usize] as char);
            }
            character => escaped.push(character),
        }
    }

    // Escape string constants keep control characters out of the physical
    // script and remain correct regardless of standard_conforming_strings.
    format!("E'{escaped}'")
}

fn postgres_schema_exists_sql(schema: &str) -> String {
    format!("SELECT 1 FROM pg_catalog.pg_namespace WHERE nspname = {} LIMIT 1", quote_string_literal(schema))
}

fn query_result_has_rows(result: &db::QueryResult) -> bool {
    !result.rows.is_empty()
}

fn is_simple_identifier(value: &str) -> bool {
    let mut chars = value.chars();
    let Some(first) = chars.next() else {
        return false;
    };
    if !(first == '_' || first.is_ascii_alphabetic()) {
        return false;
    }
    chars.all(|ch| ch == '_' || ch.is_ascii_alphanumeric())
}

fn is_postgres_compat_transfer(source_db: &DatabaseType, target_db: &DatabaseType) -> bool {
    is_postgres_transfer_dialect(source_db) && is_postgres_transfer_dialect(target_db)
}

fn is_postgres_transfer_dialect(db_type: &DatabaseType) -> bool {
    // KingbaseES supports the PostgreSQL DDL, type, and ON CONFLICT paths used by transfer;
    // other PG-wire databases stay opt-in until their transfer behavior is verified.
    matches!(db_type, DatabaseType::Postgres | DatabaseType::Kingbase)
}

fn postgres_integer_bounds(data_type: &str) -> Option<(i128, i128)> {
    let normalized = data_type.trim().to_ascii_lowercase();
    match normalized.split(['(', ' ']).next().unwrap_or("") {
        "smallint" | "int2" => Some((i128::from(i16::MIN), i128::from(i16::MAX))),
        "integer" | "int4" => Some((i128::from(i32::MIN), i128::from(i32::MAX))),
        "bigint" | "int8" => Some((i128::from(i64::MIN), i128::from(i64::MAX))),
        _ => None,
    }
}

fn is_postgres_integer_like_type(data_type: &str) -> bool {
    postgres_integer_bounds(data_type).is_some()
}

fn sqlserver_integer_bounds(data_type: &str) -> Option<(i128, i128)> {
    let normalized = data_type.trim().to_ascii_lowercase();
    match normalized.split(['(', ' ']).next().unwrap_or("") {
        "bit" => Some((i128::MIN, i128::MAX)),
        "tinyint" => Some((0, i128::from(u8::MAX))),
        "smallint" => Some((i128::from(i16::MIN), i128::from(i16::MAX))),
        "int" | "integer" => Some((i128::from(i32::MIN), i128::from(i32::MAX))),
        "bigint" => Some((i128::from(i64::MIN), i128::from(i64::MAX))),
        _ => None,
    }
}

pub(crate) fn normalize_integer_literal(
    value: &str,
    db_type: &DatabaseType,
    column_type: Option<&str>,
) -> Option<String> {
    let bounds = match db_type {
        db_type if is_postgres_transfer_dialect(db_type) => column_type.and_then(postgres_integer_bounds),
        DatabaseType::SqlServer => column_type.and_then(sqlserver_integer_bounds),
        _ => None,
    }?;

    // Excel numeric cells arrive as f64; normalize only an explicit zero fraction so real decimals,
    // scientific notation, and values outside the target integer range stay untouched.
    if value.bytes().any(|byte| matches!(byte, b'e' | b'E')) {
        return None;
    }
    let (integer, fraction) = value.split_once('.')?;
    if fraction.is_empty() || !fraction.bytes().all(|byte| byte == b'0') {
        return None;
    }
    let digits = integer.strip_prefix('-').or_else(|| integer.strip_prefix('+')).unwrap_or(integer);
    if digits.is_empty() || !digits.bytes().all(|byte| byte.is_ascii_digit()) {
        return None;
    }
    let parsed = integer.parse::<i128>().ok()?;
    if parsed < bounds.0 || parsed > bounds.1 {
        return None;
    }
    Some(integer.to_string())
}

fn is_postgres_sequence_default(default_value: Option<&str>) -> bool {
    default_value.is_some_and(|value| value.to_ascii_lowercase().contains("nextval("))
}

fn is_postgres_generated_extra(extra: Option<&str>) -> bool {
    extra.is_some_and(|value| value.trim().to_ascii_lowercase().starts_with("generated "))
}

fn is_postgres_identity_extra(extra: Option<&str>) -> bool {
    extra.is_some_and(|value| {
        let normalized = value.trim().to_ascii_lowercase();
        normalized.starts_with("generated ") && normalized.contains(" identity")
    })
}

fn is_postgres_generated_always_identity_extra(extra: Option<&str>) -> bool {
    extra.is_some_and(|value| {
        let mut parts = value.split_whitespace();
        parts.next().is_some_and(|part| part.eq_ignore_ascii_case("generated"))
            && parts.next().is_some_and(|part| part.eq_ignore_ascii_case("always"))
            && parts.next().is_some_and(|part| part.eq_ignore_ascii_case("as"))
            && parts.next().is_some_and(|part| part.eq_ignore_ascii_case("identity"))
    })
}

pub(crate) fn is_identity_column_extra(extra: Option<&str>) -> bool {
    extra.is_some_and(|value| {
        let normalized = value.trim().to_ascii_lowercase();
        normalized.contains("identity") || normalized.contains("auto_increment") || normalized.contains("autoincrement")
    })
}

pub(crate) fn is_mysql_generated_column_extra(extra: Option<&str>) -> bool {
    extra.is_some_and(|value| {
        let mut parts = value.split_whitespace();
        let Some(first) = parts.next() else {
            return false;
        };
        if first.eq_ignore_ascii_case("generated") {
            return true;
        }
        matches!(first.to_ascii_lowercase().as_str(), "virtual" | "stored" | "persistent")
            && parts.next().is_some_and(|part| part.eq_ignore_ascii_case("generated"))
    })
}

#[cfg(test)]
fn selected_columns_include_identity_extras(columns: &[String], column_extras: &[Option<String>]) -> bool {
    columns
        .iter()
        .enumerate()
        .any(|(index, _)| is_identity_column_extra(column_extras.get(index).and_then(|extra| extra.as_deref())))
}

fn selected_columns_include_identity_columns(columns: &[String], all_columns: &[db::ColumnInfo]) -> bool {
    all_columns.iter().any(|column| {
        is_identity_column_extra(column.extra.as_deref())
            && columns.iter().any(|name| name.eq_ignore_ascii_case(&column.name))
    })
}

fn selected_columns_include_postgres_generated_always_identity_columns(
    columns: &[String],
    all_columns: &[db::ColumnInfo],
) -> bool {
    all_columns.iter().any(|column| {
        is_postgres_generated_always_identity_extra(column.extra.as_deref())
            && columns.iter().any(|name| name.eq_ignore_ascii_case(&column.name))
    })
}

fn is_sqlserver_rowversion_type(data_type: &str) -> bool {
    let normalized = data_type.trim().to_ascii_lowercase();
    matches!(normalized.split(['(', ' ', '\t', '\n']).next().unwrap_or(""), "timestamp" | "rowversion")
}

fn is_sqlserver_non_insertable_transfer_column(
    column: &db::ColumnInfo,
    source_db_type: &DatabaseType,
    target_db_type: &DatabaseType,
) -> bool {
    matches!((source_db_type, target_db_type), (DatabaseType::SqlServer, DatabaseType::SqlServer))
        && is_sqlserver_rowversion_type(&column.data_type)
}

fn is_mysql_non_insertable_transfer_column(column: &db::ColumnInfo, source_db_type: &DatabaseType) -> bool {
    *source_db_type == DatabaseType::Mysql && is_mysql_generated_column_extra(column.extra.as_deref())
}

fn writable_transfer_columns(
    columns: &[db::ColumnInfo],
    source_db_type: &DatabaseType,
    target_db_type: &DatabaseType,
) -> Vec<db::ColumnInfo> {
    columns
        .iter()
        .filter(|column| {
            !is_sqlserver_non_insertable_transfer_column(column, source_db_type, target_db_type)
                && !is_mysql_non_insertable_transfer_column(column, source_db_type)
        })
        .cloned()
        .collect()
}

fn transfer_key_columns(columns: &[db::ColumnInfo], db_type: &DatabaseType) -> Vec<String> {
    let uses_unique_key_model = matches!(db_type, DatabaseType::Doris | DatabaseType::StarRocks);
    columns
        .iter()
        .filter(|column| column.is_primary_key || (uses_unique_key_model && column.is_unique))
        .map(|column| column.name.clone())
        .collect()
}

fn dameng_identity_insert_statement(table: &str, schema: &str, enabled: bool) -> String {
    let full_table = qualified_table(table, schema, &DatabaseType::Dameng, None);
    format!("SET IDENTITY_INSERT {full_table} {}", if enabled { "ON" } else { "OFF" })
}

#[cfg(test)]
fn wrap_dameng_identity_insert_sql(insert_sql: &str, table: &str, schema: &str) -> String {
    let full_table = qualified_table(table, schema, &DatabaseType::Dameng, None);
    wrap_dameng_identity_insert_sql_for_table(insert_sql, &full_table)
}

pub(crate) fn wrap_dameng_identity_insert_sql_for_table(insert_sql: &str, full_table: &str) -> String {
    let trimmed = insert_sql.trim().trim_end_matches(';').trim();
    format!("SET IDENTITY_INSERT {full_table} ON;\n{trimmed};\nSET IDENTITY_INSERT {full_table} OFF;")
}

async fn execute_transfer_write_statement(
    state: &AppState,
    target_pool_key: &str,
    sql: &str,
    target_db_type: &DatabaseType,
    table: &str,
    schema: &str,
    needs_identity_insert: bool,
) -> Result<(), String> {
    if !needs_identity_insert || !matches!(target_db_type, DatabaseType::Dameng) {
        execute_on_pool(state, target_pool_key, sql).await?;
        return Ok(());
    }

    let enable_sql = dameng_identity_insert_statement(table, schema, true);
    let disable_sql = dameng_identity_insert_statement(table, schema, false);
    execute_on_pool(state, target_pool_key, &enable_sql)
        .await
        .map_err(|e| format!("Failed to enable Dameng IDENTITY_INSERT for {table}: {e}"))?;
    let write_result = execute_on_pool(state, target_pool_key, sql).await;
    let disable_result = execute_on_pool(state, target_pool_key, &disable_sql).await;

    match (write_result, disable_result) {
        (Ok(_), Ok(_)) => Ok(()),
        (Err(write_error), Ok(_)) => Err(write_error),
        (Ok(_), Err(disable_error)) => {
            Err(format!("Failed to disable Dameng IDENTITY_INSERT for {table}: {disable_error}"))
        }
        (Err(write_error), Err(disable_error)) => {
            Err(format!("{write_error}; also failed to disable Dameng IDENTITY_INSERT for {table}: {disable_error}"))
        }
    }
}

fn rewrite_postgres_schema_qualified_references(input: &str, source_schema: &str, target_schema: &str) -> String {
    if source_schema.trim().is_empty() || source_schema == target_schema {
        return input.to_string();
    }

    let quoted_source = format!("{}.", quote_identifier(source_schema, &DatabaseType::Postgres));
    let quoted_target = format!("{}.", quote_identifier(target_schema, &DatabaseType::Postgres));
    let rewritten = input.replace(&quoted_source, &quoted_target);
    let unquoted_pattern =
        Regex::new(&format!(r#"(^|[^"\w]){}\."#, regex::escape(source_schema))).expect("valid postgres schema regex");
    unquoted_pattern
        .replace_all(&rewritten, |captures: &regex::Captures| format!("{}{}", &captures[1], quoted_target))
        .into_owned()
}

fn postgres_column_type_sql(
    column: &db::ColumnInfo,
    source_schema: &str,
    target_schema: &str,
    source_db: &DatabaseType,
    target_db: &DatabaseType,
) -> String {
    if let Some(mapped_type) = clickhouse_temporal_column_type(column, source_db, target_db) {
        return mapped_type;
    }
    if is_postgres_compat_transfer(source_db, target_db) {
        let trimmed = column.data_type.trim();
        if !trimmed.is_empty() {
            return rewrite_postgres_schema_qualified_references(trimmed, source_schema, target_schema);
        }
    }
    map_column_type(&column.data_type, source_db, target_db)
}

fn clickhouse_temporal_column_type(
    column: &db::ColumnInfo,
    source_db: &DatabaseType,
    target_db: &DatabaseType,
) -> Option<String> {
    if !matches!(target_db, DatabaseType::ClickHouse) || source_db == target_db {
        return None;
    }

    let source_type = column.data_type.trim();
    let lower = source_type.to_ascii_lowercase();
    let base = lower.split(['(', ' ', '\t', '\n']).next().unwrap_or("").trim();
    if !matches!(base, "datetime" | "timestamp" | "timestamptz") {
        return None;
    }

    let scale = clickhouse_datetime64_scale(column);
    // ClickHouse DateTime stores whole seconds, and older versions reject
    // fractional timestamp strings such as Dameng's TIMESTAMP(6) output.
    Some(format!("DateTime64({scale})"))
}

fn clickhouse_datetime64_scale(column: &db::ColumnInfo) -> u8 {
    let scale = parse_temporal_type_scale(&column.data_type).or(column.numeric_scale).unwrap_or(6);
    scale.clamp(0, 9) as u8
}

fn parse_temporal_type_scale(source_type: &str) -> Option<i32> {
    let start = source_type.find('(')? + 1;
    let rest = &source_type[start..];
    let digits = rest.bytes().take_while(|byte| byte.is_ascii_digit()).collect::<Vec<_>>();
    if digits.is_empty() {
        return None;
    }
    std::str::from_utf8(&digits).ok()?.parse::<i32>().ok()
}

fn postgres_default_clause(
    column: &db::ColumnInfo,
    source_schema: &str,
    target_schema: &str,
    source_db: &DatabaseType,
    target_db: &DatabaseType,
) -> Option<String> {
    if !is_postgres_compat_transfer(source_db, target_db) {
        return None;
    }
    if is_postgres_generated_extra(column.extra.as_deref()) {
        if let Some(extra) = column.extra.as_deref().map(str::trim).filter(|value| !value.is_empty()) {
            return Some(extra.to_string());
        }
    }
    let default_value = column.column_default.as_deref()?.trim();
    if default_value.is_empty() {
        return None;
    }
    if is_postgres_sequence_default(Some(default_value)) && is_postgres_integer_like_type(&column.data_type) {
        return Some("GENERATED BY DEFAULT AS IDENTITY".to_string());
    }
    Some(format!(
        "DEFAULT {}",
        rewrite_postgres_schema_qualified_references(default_value, source_schema, target_schema)
    ))
}

fn is_mysql_family_target(target_db: &DatabaseType) -> bool {
    matches!(
        target_db,
        DatabaseType::Mysql
            | DatabaseType::Doris
            | DatabaseType::StarRocks
            | DatabaseType::Goldendb
            | DatabaseType::Sundb
    )
}

/// QuestDB is not included. It only uses the PGWire protocol. SQL DDL syntax is not compatible.
fn is_postgres_family_target(target_db: &DatabaseType) -> bool {
    matches!(
        target_db,
        DatabaseType::Postgres
            | DatabaseType::Gaussdb
            | DatabaseType::OpenGauss
            | DatabaseType::Redshift
            | DatabaseType::Kingbase
            | DatabaseType::Highgo
            | DatabaseType::Uxdb
            | DatabaseType::Kwdb
            | DatabaseType::Vastbase
    )
}

fn is_mysql_numeric_base_type(data_type: &str) -> bool {
    let normalized = data_type.trim().to_ascii_lowercase();
    let base = normalized.split(['(', ' ']).next().unwrap_or("");
    matches!(
        base,
        "tinyint"
            | "smallint"
            | "mediumint"
            | "int"
            | "integer"
            | "bigint"
            | "decimal"
            | "numeric"
            | "float"
            | "double"
            | "real"
            | "bit"
            | "year"
    )
}

fn is_mysql_function_default(raw: &str) -> bool {
    let trimmed = raw.trim();
    if trimmed.eq_ignore_ascii_case("NULL") {
        return true;
    }
    let upper = trimmed.to_ascii_uppercase();
    if upper == "CURRENT_TIMESTAMP" || upper.starts_with("CURRENT_TIMESTAMP(") {
        return true;
    }
    if upper == "LOCALTIME" || upper.starts_with("LOCALTIME(") {
        return true;
    }
    if upper == "LOCALTIMESTAMP" || upper.starts_with("LOCALTIMESTAMP(") {
        return true;
    }
    matches!(upper.as_str(), "CURRENT_DATE" | "CURRENT_TIME" | "NOW()" | "UTC_TIMESTAMP()" | "UUID()")
}

fn looks_like_numeric_literal(raw: &str) -> bool {
    let trimmed = raw.trim();
    if trimmed.is_empty() {
        return false;
    }
    trimmed.parse::<i64>().is_ok()
        || trimmed.parse::<u64>().is_ok()
        || trimmed.parse::<f64>().is_ok_and(|value| value.is_finite())
}

fn format_mysql_default_literal(raw: &str, data_type: &str) -> String {
    let trimmed = raw.trim();
    if trimmed.eq_ignore_ascii_case("NULL") {
        return "NULL".to_string();
    }
    if is_mysql_function_default(trimmed) {
        return trimmed.to_string();
    }
    if trimmed.len() >= 2 && trimmed.starts_with('\'') && trimmed.ends_with('\'') {
        return trimmed.to_string();
    }
    if is_mysql_numeric_base_type(data_type) && looks_like_numeric_literal(trimmed) {
        return trimmed.to_string();
    }
    format!("'{}'", trimmed.replace('\'', "''"))
}

fn column_default_clause(
    column: &db::ColumnInfo,
    source_schema: &str,
    target_schema: &str,
    source_db: &DatabaseType,
    target_db: &DatabaseType,
) -> Option<String> {
    if is_postgres_compat_transfer(source_db, target_db) {
        return postgres_default_clause(column, source_schema, target_schema, source_db, target_db);
    }
    if is_mysql_family_target(target_db) {
        let default_value = column.column_default.as_deref()?.trim();
        if default_value.is_empty() {
            return None;
        }
        return Some(format!("DEFAULT {}", format_mysql_default_literal(default_value, &column.data_type)));
    }
    None
}

#[derive(Debug, Default, PartialEq, Eq)]
struct MysqlExtraClauses {
    auto_increment: bool,
    on_update: Option<String>,
}

fn parse_mysql_extra_clauses(extra: Option<&str>) -> MysqlExtraClauses {
    let mut result = MysqlExtraClauses::default();
    let Some(raw) = extra else {
        return result;
    };
    let trimmed = raw.trim();
    if trimmed.is_empty() {
        return result;
    }

    let lowered = trimmed.to_ascii_lowercase();
    if lowered.contains("auto_increment") {
        result.auto_increment = true;
    }

    let pattern = Regex::new(r"(?i)\bon\s+update\s+(.+)$").expect("valid mysql on-update regex");
    if let Some(captures) = pattern.captures(trimmed) {
        let raw_expr = captures.get(1).map(|m| m.as_str()).unwrap_or("");
        let cleaned = raw_expr.trim().trim_end_matches([',', ';', ' ']).trim();
        if !cleaned.is_empty() {
            result.on_update = Some(cleaned.to_string());
        }
    }

    result
}

fn postgres_order_by_expression(columns: &[String], db_type: &DatabaseType) -> Option<String> {
    postgres_order_by_expression_with_identifier_quote(columns, db_type, None)
}

fn postgres_order_by_expression_with_identifier_quote(
    columns: &[String],
    db_type: &DatabaseType,
    identifier_quote: Option<&str>,
) -> Option<String> {
    if columns.is_empty() {
        return None;
    }
    Some(
        columns
            .iter()
            .map(|column| quote_identifier_with_identifier_quote(column, db_type, identifier_quote))
            .collect::<Vec<_>>()
            .join(", "),
    )
}

fn oracle_rownum_page_sql(col_list: &str, base_sql: String, offset: u64, limit: usize) -> String {
    if offset == 0 {
        return format!("SELECT {col_list} FROM ({base_sql}) WHERE ROWNUM <= {limit}");
    }
    let end = offset + limit as u64;
    format!(
        "SELECT {col_list} FROM (SELECT dbx_inner.*, ROWNUM AS \"__dbx_row_num\" FROM ({base_sql}) dbx_inner WHERE ROWNUM <= {end}) WHERE \"__dbx_row_num\" > {offset}"
    )
}

fn postgres_index_column_sql(column: &str) -> String {
    if is_simple_identifier(column) {
        quote_identifier(column, &DatabaseType::Postgres)
    } else {
        column.to_string()
    }
}

fn generate_postgres_index_ddl(indexes: &[db::IndexInfo], table: &str, schema: &str) -> Vec<String> {
    let full_table = qualified_table(table, schema, &DatabaseType::Postgres, None);
    let mut statements = Vec::new();
    for index in indexes.iter().filter(|index| !index.is_primary) {
        if index.name.trim().is_empty() || index.columns.is_empty() {
            continue;
        }
        let unique = if index.is_unique { "UNIQUE " } else { "" };
        let using_clause = index
            .index_type
            .as_deref()
            .map(str::trim)
            .filter(|value| !value.is_empty())
            .map(|value| format!(" USING {value}"))
            .unwrap_or_default();
        let columns =
            index.columns.iter().map(|column| postgres_index_column_sql(column)).collect::<Vec<_>>().join(", ");
        let include_clause = index
            .included_columns
            .as_ref()
            .filter(|columns| !columns.is_empty())
            .map(|columns| {
                format!(
                    " INCLUDE ({})",
                    columns
                        .iter()
                        .map(|column| quote_identifier(column, &DatabaseType::Postgres))
                        .collect::<Vec<_>>()
                        .join(", ")
                )
            })
            .unwrap_or_default();
        let filter_clause = index
            .filter
            .as_deref()
            .map(str::trim)
            .filter(|value| !value.is_empty())
            .map(|value| format!(" WHERE {value}"))
            .unwrap_or_default();
        statements.push(format!(
            "CREATE {unique}INDEX IF NOT EXISTS {} ON {full_table}{using_clause} ({columns}){include_clause}{filter_clause}",
            quote_identifier(&index.name, &DatabaseType::Postgres)
        ));
        if let Some(comment) = index.comment.as_deref().map(str::trim).filter(|value| !value.is_empty()) {
            let qualified_index = if schema.is_empty() {
                quote_identifier(&index.name, &DatabaseType::Postgres)
            } else {
                format!(
                    "{}.{}",
                    quote_identifier(schema, &DatabaseType::Postgres),
                    quote_identifier(&index.name, &DatabaseType::Postgres)
                )
            };
            statements.push(format!("COMMENT ON INDEX {qualified_index} IS {}", quote_string_literal(comment)));
        }
    }
    statements
}

fn generate_postgres_foreign_key_ddl(
    foreign_keys: &[db::ForeignKeyInfo],
    table: &str,
    source_schema: &str,
    target_schema: &str,
) -> Vec<String> {
    let full_table = qualified_table(table, target_schema, &DatabaseType::Postgres, None);
    let mut grouped: HashMap<&str, Vec<&db::ForeignKeyInfo>> = HashMap::new();
    let mut order = Vec::new();

    for foreign_key in foreign_keys {
        if !grouped.contains_key(foreign_key.name.as_str()) {
            order.push(foreign_key.name.as_str());
        }
        grouped.entry(foreign_key.name.as_str()).or_default().push(foreign_key);
    }

    let mut statements = Vec::new();
    for name in order {
        let Some(group) = grouped.get(name) else {
            continue;
        };
        let columns = group
            .iter()
            .map(|foreign_key| quote_identifier(&foreign_key.column, &DatabaseType::Postgres))
            .collect::<Vec<_>>()
            .join(", ");
        let ref_columns = group
            .iter()
            .map(|foreign_key| quote_identifier(&foreign_key.ref_column, &DatabaseType::Postgres))
            .collect::<Vec<_>>()
            .join(", ");
        let referenced_schema = match group[0].ref_schema.as_deref() {
            Some(ref_schema) if ref_schema == source_schema => target_schema,
            Some(ref_schema) => ref_schema,
            None => target_schema,
        };
        let referenced_table = qualified_table(&group[0].ref_table, referenced_schema, &DatabaseType::Postgres, None);
        statements.push(format!(
            "ALTER TABLE {full_table} ADD CONSTRAINT {} FOREIGN KEY ({columns}) REFERENCES {referenced_table} ({ref_columns})",
            quote_identifier(name, &DatabaseType::Postgres)
        ));
    }

    statements
}

fn generate_postgres_sequence_sync_sql(columns: &[db::ColumnInfo], table: &str, schema: &str) -> Vec<String> {
    let full_table = qualified_table(table, schema, &DatabaseType::Postgres, None);
    columns
        .iter()
        .filter(|column| {
            is_postgres_sequence_default(column.column_default.as_deref())
                || is_postgres_identity_extra(column.extra.as_deref())
        })
        .map(|column| {
            let quoted_column = quote_identifier(&column.name, &DatabaseType::Postgres);
            format!(
                "SELECT setval(pg_get_serial_sequence({}, {}), GREATEST(COALESCE(MAX({quoted_column}), 0), 1), MAX({quoted_column}) IS NOT NULL) FROM {full_table}",
                quote_string_literal(&full_table),
                quote_string_literal(&column.name)
            )
        })
        .collect()
}

#[derive(Debug, Clone)]
struct PostgresOwnedSequence {
    name: String,
    owner_table: String,
    owner_column: String,
}

#[derive(Debug, Clone, PartialEq, Eq)]
struct PostgresSequenceSnapshot {
    name: String,
    owner_table: Option<String>,
    owner_column: Option<String>,
}

#[derive(Debug, Clone, PartialEq, Eq)]
struct PostgresTransferSequence {
    name: String,
    data_type: String,
    start_value: String,
    min_value: String,
    max_value: String,
    increment: String,
    cycle: bool,
    cache_value: String,
    last_value: Option<String>,
}

fn postgres_sequence_qualified_name(schema: &str, sequence_name: &str) -> String {
    if schema.trim().is_empty() {
        quote_identifier(sequence_name, &DatabaseType::Postgres)
    } else {
        format!(
            "{}.{}",
            quote_identifier(schema, &DatabaseType::Postgres),
            quote_identifier(sequence_name, &DatabaseType::Postgres)
        )
    }
}

fn generate_postgres_transfer_sequence_create_ddl(sequence: &PostgresTransferSequence, schema: &str) -> String {
    let qualified_name = postgres_sequence_qualified_name(schema, &sequence.name);
    let cycle = if sequence.cycle { "CYCLE" } else { "NO CYCLE" };
    format!(
        "CREATE SEQUENCE IF NOT EXISTS {qualified_name}\n  AS {data_type}\n  START WITH {start_value}\n  INCREMENT BY {increment}\n  MINVALUE {min_value}\n  MAXVALUE {max_value}\n  CACHE {cache_value}\n  {cycle}",
        data_type = sequence.data_type,
        start_value = sequence.start_value,
        increment = sequence.increment,
        min_value = sequence.min_value,
        max_value = sequence.max_value,
        cache_value = sequence.cache_value,
    )
}

fn generate_postgres_transfer_sequence_setval_sql(sequence: &PostgresTransferSequence, schema: &str) -> Option<String> {
    let last_value = sequence.last_value.as_deref()?.trim();
    if last_value.is_empty() {
        return None;
    }
    Some(format!(
        "SELECT setval({}, {last_value}, true)",
        quote_postgres_string_literal(&postgres_sequence_qualified_name(schema, &sequence.name))
    ))
}

/// Reuse an existing target sequence only when it is already bound to the same
/// target table column; otherwise the later `OWNED BY` rebind would silently
/// change unrelated objects.
fn validate_existing_postgres_sequence(
    sequence: &PostgresOwnedSequence,
    existing: Option<&PostgresSequenceSnapshot>,
    schema: &str,
) -> Result<bool, String> {
    let Some(existing) = existing else {
        return Ok(true);
    };

    let owner_matches = match (existing.owner_table.as_deref(), existing.owner_column.as_deref()) {
        (None, None) => true,
        (Some(owner_table), Some(owner_column)) => {
            owner_table == sequence.owner_table && owner_column == sequence.owner_column
        }
        _ => false,
    };

    if owner_matches {
        return Ok(false);
    }

    Err(format!(
        "PostgreSQL sequence {} already exists with incompatible ownership",
        postgres_sequence_qualified_name(schema, &sequence.name)
    ))
}
#[derive(Debug, Clone)]
struct PostgresTriggerSource {
    table_name: String,
    trigger_name: String,
    source: String,
}

#[derive(Debug, Clone)]
struct PostgresExtensionSource {
    extension_name: String,
}

#[derive(Debug, Clone)]
struct PostgresEnumSource {
    type_name: String,
    labels: Vec<String>,
}

#[derive(Debug, Clone)]
struct PostgresDomainSource {
    domain_name: String,
    base_type: String,
    default_value: Option<String>,
    not_null: bool,
    checks: Vec<String>,
}

#[derive(Debug, Clone)]
struct PostgresMaterializedViewSource {
    view_name: String,
    source: String,
}

#[derive(Debug, Clone)]
struct PostgresOwnershipStatement {
    sql_prefix: String,
    owner: String,
}

fn json_string_cell(row: &[serde_json::Value], index: usize) -> Option<String> {
    row.get(index).and_then(|value| value.as_str().map(str::to_string))
}

fn result_rows_to_string_statements(rows: Vec<Vec<serde_json::Value>>) -> Vec<String> {
    rows.into_iter().filter_map(|row| json_string_cell(&row, 0)).filter(|stmt| !stmt.trim().is_empty()).collect()
}

fn result_rows_to_postgres_ownership_statements(rows: Vec<Vec<serde_json::Value>>) -> Vec<PostgresOwnershipStatement> {
    rows.into_iter()
        .filter_map(|row| {
            let sql_prefix = json_string_cell(&row, 0)?;
            let owner = json_string_cell(&row, 1)?;
            if sql_prefix.trim().is_empty() || owner.trim().is_empty() {
                None
            } else {
                Some(PostgresOwnershipStatement { sql_prefix, owner })
            }
        })
        .collect()
}

fn ensure_sql_statement_terminated(sql: &str) -> String {
    let trimmed = sql.trim();
    if trimmed.ends_with(';') {
        trimmed.to_string()
    } else {
        format!("{trimmed};")
    }
}

fn generate_postgres_extension_ddl(extension: &PostgresExtensionSource, target_schema: &str) -> String {
    format!(
        "CREATE EXTENSION IF NOT EXISTS {} WITH SCHEMA {}",
        quote_identifier(&extension.extension_name, &DatabaseType::Postgres),
        quote_identifier(target_schema, &DatabaseType::Postgres)
    )
}

fn generate_postgres_enum_ddl(enum_type: &PostgresEnumSource, target_schema: &str) -> String {
    let labels = enum_type.labels.iter().map(|label| quote_string_literal(label)).collect::<Vec<_>>().join(", ");
    let create_sql = format!(
        "CREATE TYPE {}.{} AS ENUM ({labels})",
        quote_identifier(target_schema, &DatabaseType::Postgres),
        quote_identifier(&enum_type.type_name, &DatabaseType::Postgres)
    );
    format!(
        "DO $$ BEGIN IF NOT EXISTS (SELECT 1 FROM pg_type t JOIN pg_namespace n ON n.oid = t.typnamespace WHERE n.nspname = {} AND t.typname = {}) THEN {create_sql}; END IF; END $$",
        quote_string_literal(target_schema),
        quote_string_literal(&enum_type.type_name)
    )
}

fn generate_postgres_domain_ddl(domain: &PostgresDomainSource, target_schema: &str) -> String {
    let mut create_sql = format!(
        "CREATE DOMAIN {}.{} AS {}",
        quote_identifier(target_schema, &DatabaseType::Postgres),
        quote_identifier(&domain.domain_name, &DatabaseType::Postgres),
        domain.base_type
    );
    if let Some(default_value) = domain.default_value.as_deref().map(str::trim).filter(|value| !value.is_empty()) {
        create_sql.push_str(&format!(" DEFAULT {default_value}"));
    }
    if domain.not_null {
        create_sql.push_str(" NOT NULL");
    }
    for check in &domain.checks {
        create_sql.push(' ');
        create_sql.push_str(check);
    }
    format!(
        "DO $$ BEGIN IF NOT EXISTS (SELECT 1 FROM pg_type t JOIN pg_namespace n ON n.oid = t.typnamespace WHERE n.nspname = {} AND t.typname = {}) THEN {}; END IF; END $$",
        quote_string_literal(target_schema),
        quote_string_literal(&domain.domain_name),
        create_sql
    )
}

fn generate_postgres_materialized_view_ddls(view: &PostgresMaterializedViewSource, target_schema: &str) -> Vec<String> {
    let qualified_name = qualified_table(&view.view_name, target_schema, &DatabaseType::Postgres, None);
    vec![
        format!("DROP MATERIALIZED VIEW IF EXISTS {qualified_name}"),
        format!("CREATE MATERIALIZED VIEW {qualified_name} AS\n{}", ensure_sql_statement_terminated(&view.source)),
    ]
}

fn rewrite_postgres_routine_schema(source: &str, source_schema: &str, target_schema: &str) -> Option<String> {
    let re = Regex::new(
        r#"(?is)^(\s*CREATE\s+(?:OR\s+REPLACE\s+)?(?:(?:NON)?EDITIONABLE\s+)?(?:FUNCTION|PROCEDURE)\s+)((?:"(?:""|[^"])+"|[A-Za-z_][\w$]*)(?:\s*\.\s*(?:"(?:""|[^"])+"|[A-Za-z_][\w$]*))?)"#,
    )
    .ok()?;
    let captures = re.captures(source)?;
    let full = captures.get(0)?;
    let prefix = captures.get(1)?.as_str();
    let existing_name = captures.get(2)?.as_str();
    let name_re = Regex::new(r#""(?:""|[^"])+"|[A-Za-z_][\w$]*"#).ok()?;
    let parts = name_re
        .find_iter(existing_name)
        .map(|part| part.as_str().trim().trim_matches('"').replace("\"\"", "\""))
        .collect::<Vec<_>>();
    let name = parts.last()?;
    let replacement = format!(
        "{}.{}",
        quote_identifier(target_schema, &DatabaseType::Postgres),
        quote_identifier(name, &DatabaseType::Postgres)
    );
    let rewritten = format!("{}{}{}{}", &source[..full.start()], prefix, replacement, &source[full.end()..]);
    Some(rewrite_postgres_schema_qualified_references(&rewritten, source_schema, target_schema))
}

fn rewrite_postgres_trigger_table_schema(
    source: &str,
    source_schema: &str,
    table_name: &str,
    target_schema: &str,
) -> String {
    let qualified_target_table = qualified_table(table_name, target_schema, &DatabaseType::Postgres, None);
    let candidate_patterns = [
        format!(
            " ON {}.{} ",
            quote_identifier(source_schema, &DatabaseType::Postgres),
            quote_identifier(table_name, &DatabaseType::Postgres)
        ),
        format!(" ON {source_schema}.{table_name} "),
        format!(" ON {} ", quote_identifier(table_name, &DatabaseType::Postgres)),
        format!(" ON {table_name} "),
    ];
    for pattern in candidate_patterns {
        if source.contains(&pattern) {
            let rewritten = source.replacen(&pattern, &format!(" ON {qualified_target_table} "), 1);
            return rewrite_postgres_schema_qualified_references(&rewritten, source_schema, target_schema);
        }
    }
    rewrite_postgres_schema_qualified_references(source, source_schema, target_schema)
}

pub fn escape_value(val: &serde_json::Value, db_type: &DatabaseType) -> String {
    escape_value_typed(val, db_type, None)
}

pub fn escape_value_typed(val: &serde_json::Value, db_type: &DatabaseType, column_type: Option<&str>) -> String {
    match val {
        serde_json::Value::Null => "NULL".to_string(),
        serde_json::Value::Bool(b) => match db_type {
            DatabaseType::Mysql
            | DatabaseType::Sqlite
            | DatabaseType::CloudflareD1
            | DatabaseType::DuckDb
            | DatabaseType::Doris
            | DatabaseType::StarRocks => {
                if *b {
                    if column_type.is_some_and(is_mysql_bit_type) {
                        "b'1'".to_string()
                    } else {
                        "1".to_string()
                    }
                } else if column_type.is_some_and(is_mysql_bit_type) {
                    "b'0'".to_string()
                } else {
                    "0".to_string()
                }
            }
            DatabaseType::SqlServer | DatabaseType::Dameng => {
                if *b {
                    "1".to_string()
                } else {
                    "0".to_string()
                }
            }
            _ => {
                if *b {
                    "TRUE".to_string()
                } else {
                    "FALSE".to_string()
                }
            }
        },
        serde_json::Value::Number(n) => {
            if let Some(integer_literal) = normalize_integer_literal(&n.to_string(), db_type, column_type) {
                return integer_literal;
            }
            match db_type {
                DatabaseType::Mysql | DatabaseType::Doris | DatabaseType::StarRocks => {
                    if column_type.is_some_and(is_mysql_bit_type) {
                        format!("b'{}'", n)
                    } else {
                        n.to_string()
                    }
                }
                _ => n.to_string(),
            }
        }
        serde_json::Value::String(s) => {
            if let Some(integer_literal) = normalize_integer_literal(s, db_type, column_type) {
                return integer_literal;
            }
            if let Some(binary_literal) = format_postgres_binary_sql_literal(s, db_type, column_type) {
                return binary_literal;
            }
            if let Some(binary_literal) = format_mysql_binary_sql_literal(s, db_type, column_type) {
                return binary_literal;
            }
            if let Some(binary_literal) = format_sqlserver_binary_sql_literal(s, db_type, column_type) {
                return binary_literal;
            }
            if let Some(numeric_literal) = format_mysql_numeric_string_literal(s, db_type, column_type) {
                return numeric_literal;
            }
            if let Some(temporal_literal) = format_oracle_temporal_sql_literal(s, db_type, column_type) {
                return temporal_literal;
            }

            let literal = format_literal_string(s, db_type, column_type);
            if *db_type == DatabaseType::Postgres {
                return quote_postgres_string_literal(&literal);
            }
            let escaped = if is_postgres_family_target(db_type) || *db_type == DatabaseType::SqlServer {
                literal.replace('\'', "''")
            } else {
                literal.replace('\\', "\\\\").replace('\'', "''")
            };
            match db_type {
                DatabaseType::Mysql | DatabaseType::Doris | DatabaseType::StarRocks
                    if column_type.is_some_and(is_mysql_bit_type) =>
                {
                    format!("b'{escaped}'")
                }
                DatabaseType::SqlServer => format!("N'{escaped}'"),
                _ => format!("'{escaped}'"),
            }
        }
        serde_json::Value::Array(arr) => match db_type {
            DatabaseType::ClickHouse | DatabaseType::Databend => format_ch_array_sql_literal(arr),
            _ => format_pg_array_sql_literal(arr),
        },
        _ => {
            let s = val.to_string();
            format!("'{}'", s.replace('\\', "\\\\").replace('\'', "''"))
        }
    }
}

fn is_mysql_bit_type(column_type: &str) -> bool {
    let trimmed = column_type.trim();
    let lower = trimmed.to_ascii_lowercase();
    lower == "bit" || lower.starts_with("bit(") || lower.starts_with("bit ")
}

fn is_mysql_numeric_string_literal_database(db_type: &DatabaseType) -> bool {
    matches!(
        db_type,
        DatabaseType::Mysql
            | DatabaseType::Doris
            | DatabaseType::StarRocks
            | DatabaseType::Goldendb
            | DatabaseType::Sundb
    )
}

fn is_mysql_non_bit_numeric_type(column_type: &str) -> bool {
    is_mysql_numeric_base_type(column_type) && !is_mysql_bit_type(column_type)
}

fn format_mysql_numeric_string_literal(
    value: &str,
    db_type: &DatabaseType,
    column_type: Option<&str>,
) -> Option<String> {
    if !is_mysql_numeric_string_literal_database(db_type) || !column_type.is_some_and(is_mysql_non_bit_numeric_type) {
        return None;
    }
    let trimmed = value.trim();
    if looks_like_numeric_literal(trimmed) {
        Some(trimmed.to_string())
    } else {
        None
    }
}

fn is_binary_transfer_column_type(column_type: &str) -> bool {
    let lower = column_type.trim().to_ascii_lowercase();
    let base = lower.split(['(', ' ', '\t', '\n']).next().unwrap_or("");
    matches!(base, "binary" | "varbinary" | "blob" | "tinyblob" | "mediumblob" | "longblob" | "bytea" | "image")
}

fn format_postgres_binary_sql_literal(
    value: &str,
    db_type: &DatabaseType,
    column_type: Option<&str>,
) -> Option<String> {
    if !matches!(db_type, DatabaseType::Postgres) || !column_type.is_some_and(is_binary_transfer_column_type) {
        return None;
    }

    let hex = value.strip_prefix("0x").or_else(|| value.strip_prefix("0X"))?;
    if hex.len() % 2 != 0 || !hex.as_bytes().iter().all(|byte| byte.is_ascii_hexdigit()) {
        return None;
    }

    Some(format!("decode('{hex}', 'hex')"))
}

fn format_mysql_binary_sql_literal(value: &str, db_type: &DatabaseType, column_type: Option<&str>) -> Option<String> {
    if !matches!(db_type, DatabaseType::Mysql) || !column_type.is_some_and(is_binary_transfer_column_type) {
        return None;
    }

    let trimmed = value.trim();
    let hex = trimmed.strip_prefix("0x").or_else(|| trimmed.strip_prefix("0X"))?;
    if hex.as_bytes().iter().all(|byte| byte.is_ascii_hexdigit()) {
        Some(if hex.is_empty() { "X''".to_string() } else { format!("0x{hex}") })
    } else {
        None
    }
}

fn format_sqlserver_binary_sql_literal(
    value: &str,
    db_type: &DatabaseType,
    column_type: Option<&str>,
) -> Option<String> {
    if !matches!(db_type, DatabaseType::SqlServer) {
        return None;
    }
    let column_type = column_type.filter(|column_type| is_binary_transfer_column_type(column_type))?;

    let trimmed = value.trim();
    if let Some(hex) = trimmed.strip_prefix("0x").or_else(|| trimmed.strip_prefix("0X")) {
        if hex.len() % 2 == 0 && hex.as_bytes().iter().all(|byte| byte.is_ascii_hexdigit()) {
            return Some(format!("0x{hex}"));
        }
    }
    // SQL Server does not implicitly convert NVARCHAR literals to binary targets.
    // Use the target type so text fallback preserves the same Unicode byte encoding
    // that a direct typed conversion would produce.
    let escaped = value.replace('\'', "''");
    Some(format!("CONVERT({column_type}, N'{escaped}')"))
}

fn format_oracle_temporal_sql_literal(
    value: &str,
    db_type: &DatabaseType,
    column_type: Option<&str>,
) -> Option<String> {
    if !matches!(db_type, DatabaseType::Oracle | DatabaseType::OceanbaseOracle) {
        return None;
    }
    let kind = temporal_column_kind(column_type)?;
    let normalized_column_type = column_type?.trim().to_ascii_lowercase();
    let parts = oracle_export_date_parts(value)?;
    match kind {
        "date" => Some(format_oracle_date_sql_literal_parts(&parts)),
        "datetime"
            if (normalized_column_type.contains("with time zone")
                || normalized_column_type.contains("with local time zone"))
                && parts.zone.is_some() =>
        {
            let fraction = parts.fraction.unwrap_or_default();
            let mask = if fraction.is_empty() { "YYYY-MM-DD HH24:MI:SS" } else { "YYYY-MM-DD HH24:MI:SS.FF" };
            let zone = match parts.zone.unwrap_or_default() {
                "Z" | "z" => "+00:00",
                zone => zone,
            };
            Some(format!("TO_TIMESTAMP_TZ('{} {}{fraction} {zone}', '{mask} TZH:TZM')", parts.date, parts.time))
        }
        "datetime" => {
            let fraction = parts.fraction.unwrap_or_default();
            let mask = if fraction.is_empty() { "YYYY-MM-DD HH24:MI:SS" } else { "YYYY-MM-DD HH24:MI:SS.FF" };
            Some(format!("TO_TIMESTAMP('{} {}{fraction}', '{mask}')", parts.date, parts.time))
        }
        _ => None,
    }
}

struct OracleExportDateParts<'a> {
    date: &'a str,
    time: &'a str,
    fraction: Option<&'a str>,
    zone: Option<&'a str>,
}

fn format_oracle_date_sql_literal_parts(parts: &OracleExportDateParts<'_>) -> String {
    if oracle_export_date_parts_are_midnight(parts) {
        format!("DATE '{}'", parts.date)
    } else {
        format!("TO_DATE('{} {}', 'YYYY-MM-DD HH24:MI:SS')", parts.date, parts.time)
    }
}

fn oracle_export_date_parts_are_midnight(parts: &OracleExportDateParts<'_>) -> bool {
    parts.time == "00:00:00"
        && parts.fraction.map(|fraction| fraction.trim_start_matches('.').chars().all(|ch| ch == '0')).unwrap_or(true)
}

fn oracle_export_date_parts(value: &str) -> Option<OracleExportDateParts<'_>> {
    let bytes = value.as_bytes();
    if bytes.len() < 10 || bytes.get(4) != Some(&b'-') || bytes.get(7) != Some(&b'-') {
        return None;
    }
    let date = &value[..10];
    if !date.as_bytes().iter().enumerate().all(|(index, byte)| matches!(index, 4 | 7) || byte.is_ascii_digit()) {
        return None;
    }
    if bytes.len() == 10 {
        return Some(OracleExportDateParts { date, time: "00:00:00", fraction: None, zone: None });
    }
    let separator = *bytes.get(10)?;
    if separator != b'T' && separator != b' ' {
        return None;
    }
    if bytes.len() < 19 || bytes.get(13) != Some(&b':') || bytes.get(16) != Some(&b':') {
        return None;
    }
    let time = &value[11..19];
    if !time.as_bytes().iter().enumerate().all(|(index, byte)| matches!(index, 2 | 5) || byte.is_ascii_digit()) {
        return None;
    }
    let rest = &value[19..];
    if rest.is_empty() || is_timezone_suffix(rest) {
        return Some(OracleExportDateParts { date, time, fraction: None, zone: (!rest.is_empty()).then_some(rest) });
    }
    if let Some(after_dot) = rest.strip_prefix('.') {
        let digit_count = after_dot.bytes().take_while(|byte| byte.is_ascii_digit()).count();
        if digit_count == 0 {
            return None;
        }
        let zone = &after_dot[digit_count..];
        if zone.is_empty() || is_timezone_suffix(zone) {
            return Some(OracleExportDateParts {
                date,
                time,
                fraction: Some(&value[19..19 + 1 + digit_count]),
                zone: (!zone.is_empty()).then_some(zone),
            });
        }
    }
    None
}

pub fn format_pg_array_sql_literal(arr: &[serde_json::Value]) -> String {
    if arr.is_empty() {
        return "'{}'".to_string();
    }
    let elements: Vec<String> = arr.iter().map(format_pg_array_element).collect();
    let inner = format!("{{{}}}", elements.join(","));
    format!("'{}'", inner.replace('\\', "\\\\").replace('\'', "''"))
}

fn format_pg_array_element(val: &serde_json::Value) -> String {
    match val {
        serde_json::Value::Null => "NULL".to_string(),
        serde_json::Value::Array(arr) => {
            if arr.is_empty() {
                return "{}".to_string();
            }
            let elements: Vec<String> = arr.iter().map(format_pg_array_element).collect();
            format!("{{{}}}", elements.join(","))
        }
        serde_json::Value::String(s) => {
            let escaped = s.replace('\\', "\\\\").replace('"', "\\\"");
            format!("\"{}\"", escaped)
        }
        serde_json::Value::Number(n) => n.to_string(),
        serde_json::Value::Bool(b) => {
            if *b {
                "true".to_string()
            } else {
                "false".to_string()
            }
        }
        serde_json::Value::Object(o) => {
            let json = serde_json::to_string(o).unwrap_or_default();
            let escaped = json.replace('\\', "\\\\").replace('"', "\\\"");
            format!("\"{}\"", escaped)
        }
    }
}

pub fn format_ch_array_sql_literal(arr: &[serde_json::Value]) -> String {
    if arr.is_empty() {
        return "[]".to_string();
    }
    let elements: Vec<String> = arr.iter().map(format_ch_array_element).collect();
    format!("[{}]", elements.join(","))
}

fn format_ch_array_element(val: &serde_json::Value) -> String {
    match val {
        serde_json::Value::Null => "NULL".to_string(),
        serde_json::Value::Array(arr) => {
            if arr.is_empty() {
                return "[]".to_string();
            }
            let elements: Vec<String> = arr.iter().map(format_ch_array_element).collect();
            format!("[{}]", elements.join(","))
        }
        serde_json::Value::String(s) => {
            let escaped = s.replace('\\', "\\\\").replace('\'', "''");
            format!("'{}'", escaped)
        }
        serde_json::Value::Number(n) => n.to_string(),
        serde_json::Value::Bool(b) => {
            if *b {
                "true".to_string()
            } else {
                "false".to_string()
            }
        }
        serde_json::Value::Object(o) => {
            let json = serde_json::to_string(o).unwrap_or_default();
            format!("'{}'", json.replace('\\', "\\\\").replace('\'', "''"))
        }
    }
}

fn format_literal_string(value: &str, db_type: &DatabaseType, column_type: Option<&str>) -> String {
    if *db_type == DatabaseType::SqlServer {
        crate::sqlserver_temporal::normalize_sqlserver_temporal_literal(value, column_type)
            .unwrap_or_else(|| value.to_string())
    } else if is_mysql_datetime_literal_database(db_type) && column_type.map(is_temporal_column_type).unwrap_or(true) {
        normalize_mysql_temporal_literal(value, column_type).unwrap_or_else(|| value.to_string())
    } else {
        value.to_string()
    }
}

fn is_mysql_datetime_literal_database(db_type: &DatabaseType) -> bool {
    matches!(
        db_type,
        DatabaseType::Mysql
            | DatabaseType::Doris
            | DatabaseType::StarRocks
            | DatabaseType::Goldendb
            | DatabaseType::Sundb
    )
}

fn normalize_mysql_temporal_literal(value: &str, column_type: Option<&str>) -> Option<String> {
    let bytes = value.as_bytes();
    if bytes.len() < 20 || !is_mysql_datetime_base(bytes) {
        return None;
    }

    let rest = &value[19..];
    let (fraction, offset) = if let Some(after_dot) = rest.strip_prefix('.') {
        let digit_count = after_dot.bytes().take_while(|b| b.is_ascii_digit()).count();
        if digit_count == 0 {
            return None;
        }
        let fraction_len = 1 + digit_count;
        (&rest[..fraction_len.min(7)], &rest[fraction_len..])
    } else {
        ("", rest)
    };

    if !is_timezone_suffix(offset) {
        return None;
    }

    match temporal_column_kind(column_type) {
        Some("date") => Some(value[..10].to_string()),
        Some("time") => Some(format!("{}{}", &value[11..19], fraction)),
        _ => Some(format!("{} {}{}", &value[..10], &value[11..19], fraction)),
    }
}

fn is_temporal_column_type(column_type: &str) -> bool {
    temporal_column_kind(Some(column_type)).is_some()
}

fn temporal_column_kind(column_type: Option<&str>) -> Option<&'static str> {
    let base = column_type?.trim().to_ascii_lowercase();
    let base = base.split(['(', ':', ' ']).next().unwrap_or("");
    match base {
        "date" => Some("date"),
        "time" => Some("time"),
        "datetime" | "timestamp" => Some("datetime"),
        _ => None,
    }
}

fn is_mysql_datetime_base(bytes: &[u8]) -> bool {
    matches!(
        bytes,
        [
            y0,
            y1,
            y2,
            y3,
            b'-',
            m0,
            m1,
            b'-',
            d0,
            d1,
            sep,
            h0,
            h1,
            b':',
            min0,
            min1,
            b':',
            s0,
            s1,
            ..
        ] if y0.is_ascii_digit()
            && y1.is_ascii_digit()
            && y2.is_ascii_digit()
            && y3.is_ascii_digit()
            && m0.is_ascii_digit()
            && m1.is_ascii_digit()
            && d0.is_ascii_digit()
            && d1.is_ascii_digit()
            && (*sep == b'T' || *sep == b' ')
            && h0.is_ascii_digit()
            && h1.is_ascii_digit()
            && min0.is_ascii_digit()
            && min1.is_ascii_digit()
            && s0.is_ascii_digit()
            && s1.is_ascii_digit()
    )
}

fn is_timezone_suffix(value: &str) -> bool {
    if value.eq_ignore_ascii_case("z") {
        return true;
    }
    let bytes = value.as_bytes();
    matches!(
        bytes,
        [sign, h0, h1, b':', m0, m1]
            if (*sign == b'+' || *sign == b'-')
                && h0.is_ascii_digit()
                && h1.is_ascii_digit()
                && m0.is_ascii_digit()
                && m1.is_ascii_digit()
    )
}

pub fn map_column_type(source_type: &str, _source_db: &DatabaseType, target_db: &DatabaseType) -> String {
    if _source_db == target_db {
        return source_type.to_string();
    }
    let t = source_type.to_lowercase();
    let mut base = t.split('(').next().unwrap_or(&t).trim();
    // Extract basic type, `bigint unsigned` -> `bigint`
    base = base.split(' ').next().unwrap_or(base).trim();

    if matches!(target_db, DatabaseType::Hive) {
        return match base {
            "tinyint" => "TINYINT".into(),
            "smallint" | "int2" => "SMALLINT".into(),
            "int" | "integer" | "int4" | "mediumint" | "serial" | "smallserial" => "INT".into(),
            "bigint" | "int8" | "bigserial" => "BIGINT".into(),
            "float" | "float4" | "real" => "FLOAT".into(),
            "double" | "double precision" | "float8" => "DOUBLE".into(),
            "decimal" | "numeric" | "number" => {
                if let Some(index) = t.find('(') {
                    format!("DECIMAL{}", &t[index..])
                } else {
                    "DECIMAL".into()
                }
            }
            "bool" | "boolean" | "bit" => "BOOLEAN".into(),
            "date" => "DATE".into(),
            "datetime" | "timestamp" | "timestamptz" | "timestamp with time zone" | "timestamp without time zone" => {
                "TIMESTAMP".into()
            }
            "binary" | "varbinary" | "blob" | "tinyblob" | "mediumblob" | "longblob" | "bytea" | "image" => {
                "BINARY".into()
            }
            _ => "STRING".into(),
        };
    }

    match base {
        "int" | "integer" | "int4" | "mediumint" => match target_db {
            target_db if is_postgres_transfer_dialect(target_db) => "INTEGER".into(),
            DatabaseType::Mysql => "INT".into(),
            DatabaseType::SqlServer => "INT".into(),
            _ => "INTEGER".into(),
        },
        "bigint" | "int8" => "BIGINT".into(),
        "smallint" | "int2" => "SMALLINT".into(),
        "tinyint" => match target_db {
            target_db if is_postgres_transfer_dialect(target_db) => "SMALLINT".into(),
            _ => "TINYINT".into(),
        },
        "serial" | "bigserial" | "smallserial" => match target_db {
            target_db if is_postgres_transfer_dialect(target_db) => source_type.to_uppercase(),
            DatabaseType::Mysql => "BIGINT AUTO_INCREMENT".into(),
            _ => "INTEGER".into(),
        },
        "float" | "float4" | "real" => match target_db {
            target_db if is_postgres_transfer_dialect(target_db) => "REAL".into(),
            _ => "FLOAT".into(),
        },
        "double" | "double precision" | "float8" => match target_db {
            target_db if is_postgres_transfer_dialect(target_db) => "DOUBLE PRECISION".into(),
            _ => "DOUBLE".into(),
        },
        "decimal" | "numeric" | "number" => {
            if t.contains('(') {
                match target_db {
                    DatabaseType::Mysql | DatabaseType::SqlServer | DatabaseType::Oracle => {
                        format!("DECIMAL{}", &t[t.find('(').unwrap()..])
                    }
                    target_db if is_postgres_transfer_dialect(target_db) => {
                        format!("DECIMAL{}", &t[t.find('(').unwrap()..])
                    }
                    _ => "NUMERIC".into(),
                }
            } else {
                "NUMERIC".into()
            }
        }
        "varchar" | "nvarchar" | "character varying" | "varchar2" => {
            if t.contains('(') {
                let len_part = &t[t.find('(').unwrap()..];
                match target_db {
                    target_db if is_postgres_transfer_dialect(target_db) => format!("VARCHAR{len_part}"),
                    DatabaseType::Mysql => format!("VARCHAR{len_part}"),
                    DatabaseType::SqlServer => format!("NVARCHAR{len_part}"),
                    _ => format!("VARCHAR{len_part}"),
                }
            } else {
                "VARCHAR(255)".into()
            }
        }
        "char" | "nchar" | "character" => {
            if t.contains('(') {
                let len_part = &t[t.find('(').unwrap()..];
                format!("CHAR{len_part}")
            } else {
                "CHAR(1)".into()
            }
        }
        "longtext" => match target_db {
            DatabaseType::Mysql => "LONGTEXT".into(),
            _ => "TEXT".into(),
        },
        "mediumtext" => match target_db {
            DatabaseType::Mysql => "MEDIUMTEXT".into(),
            _ => "TEXT".into(),
        },
        "text" | "tinytext" | "clob" | "ntext" => "TEXT".into(),
        "bool" | "boolean" => match target_db {
            DatabaseType::Mysql => "TINYINT(1)".into(),
            DatabaseType::SqlServer => "BIT".into(),
            _ => "BOOLEAN".into(),
        },
        "date" => "DATE".into(),
        "time" => "TIME".into(),
        "datetime" => match target_db {
            target_db if is_postgres_transfer_dialect(target_db) => "TIMESTAMP".into(),
            DatabaseType::ClickHouse => "DateTime64(6)".into(),
            _ => "DATETIME".into(),
        },
        "timestamp" | "timestamptz" | "timestamp with time zone" | "timestamp without time zone" => match target_db {
            DatabaseType::Mysql => "DATETIME".into(),
            DatabaseType::SqlServer => "DATETIME2".into(),
            DatabaseType::ClickHouse => "DateTime64(6)".into(),
            _ => "TIMESTAMP".into(),
        },
        "longblob" => match target_db {
            DatabaseType::Mysql => "LONGBLOB".into(),
            target_db if is_postgres_transfer_dialect(target_db) => "BYTEA".into(),
            DatabaseType::SqlServer => "VARBINARY(MAX)".into(),
            _ => "BLOB".into(),
        },
        "mediumblob" => match target_db {
            DatabaseType::Mysql => "MEDIUMBLOB".into(),
            target_db if is_postgres_transfer_dialect(target_db) => "BYTEA".into(),
            DatabaseType::SqlServer => "VARBINARY(MAX)".into(),
            _ => "BLOB".into(),
        },
        "blob" | "tinyblob" | "binary" | "varbinary" | "image" => match target_db {
            target_db if is_postgres_transfer_dialect(target_db) => "BYTEA".into(),
            DatabaseType::Mysql => "BLOB".into(),
            DatabaseType::SqlServer => "VARBINARY(MAX)".into(),
            _ => "BLOB".into(),
        },
        "bytea" => match target_db {
            target_db if is_postgres_transfer_dialect(target_db) => "BYTEA".into(),
            DatabaseType::Mysql => "BLOB".into(),
            _ => "BLOB".into(),
        },
        "json" | "jsonb" => match target_db {
            target_db if is_postgres_transfer_dialect(target_db) => "JSONB".into(),
            DatabaseType::Mysql => "JSON".into(),
            _ => "TEXT".into(),
        },
        "uuid" => match target_db {
            target_db if is_postgres_transfer_dialect(target_db) => "UUID".into(),
            _ => "VARCHAR(36)".into(),
        },
        "bit" => match target_db {
            target_db if is_postgres_transfer_dialect(target_db) => "BOOLEAN".into(),
            _ => "BIT".into(),
        },
        _ => "TEXT".into(),
    }
}

fn mysql_type_needs_key_prefix(mapped_type: &str) -> bool {
    let base = mapped_type.split('(').next().unwrap_or(mapped_type).trim().to_ascii_lowercase();
    matches!(
        base.as_str(),
        "text" | "tinytext" | "mediumtext" | "longtext" | "blob" | "tinyblob" | "mediumblob" | "longblob"
    )
}

fn parse_mysql_row_error(error: &str) -> Option<u64> {
    let error = error.trim();
    let at_row = error.rsplit("at row ").next()?;
    at_row.trim().parse::<u64>().ok()
}

pub fn generate_create_table_ddl(
    columns: &[db::ColumnInfo],
    table: &str,
    source_schema: &str,
    schema: &str,
    target_db: &DatabaseType,
    source_db: &DatabaseType,
    table_comment: Option<&str>,
    catalog: Option<&str>,
) -> String {
    let full_table = qualified_table(table, schema, target_db, catalog);

    let is_mysql_family = matches!(
        target_db,
        DatabaseType::Mysql
            | DatabaseType::Doris
            | DatabaseType::StarRocks
            | DatabaseType::Goldendb
            | DatabaseType::Sundb
    );

    let mut col_lines = Vec::with_capacity(columns.len());
    for c in columns {
        col_lines.push({
            let mapped_type = postgres_column_type_sql(c, source_schema, schema, source_db, target_db);
            let mut line = format!("  {} {}", quote_identifier(&c.name, target_db), mapped_type);
            if let Some(default_clause) = column_default_clause(c, source_schema, schema, source_db, target_db) {
                line.push(' ');
                line.push_str(&default_clause);
            }
            if !c.is_nullable && !matches!(target_db, DatabaseType::Hive) {
                line.push_str(" NOT NULL");
            }
            if is_mysql_family {
                let extra_clauses = parse_mysql_extra_clauses(c.extra.as_deref());
                if extra_clauses.auto_increment {
                    line.push_str(" AUTO_INCREMENT");
                }
                if let Some(on_update_expr) = extra_clauses.on_update {
                    line.push_str(&format!(" ON UPDATE {on_update_expr}"));
                }
                if let Some(ref comment) = c.comment {
                    let trimmed = comment.trim();
                    if !trimmed.is_empty() {
                        line.push_str(&format!(" COMMENT '{}'", trimmed.replace('\'', "''")));
                    }
                }
            }
            line
        });
    }

    let mut pks = Vec::with_capacity(columns.iter().filter(|c| c.is_primary_key).count());
    if !matches!(target_db, DatabaseType::Hive) {
        for c in columns {
            if c.is_primary_key {
                let qname = quote_identifier(&c.name, target_db);
                if is_mysql_family {
                    let mapped = map_column_type(&c.data_type, source_db, target_db);
                    if mysql_type_needs_key_prefix(&mapped) {
                        pks.push(format!("{qname}(255)"));
                        continue;
                    }
                }
                pks.push(qname);
            }
        }
    }

    let mut ddl = match target_db {
        DatabaseType::SqlServer => {
            format!("IF NOT EXISTS (SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = '{table}')\n")
        }
        _ => String::new(),
    };

    let create_prefix = match target_db {
        DatabaseType::SqlServer | DatabaseType::Dameng => "CREATE TABLE",
        _ => "CREATE TABLE IF NOT EXISTS",
    };

    ddl.push_str(&format!("{create_prefix} {full_table} (\n"));
    ddl.push_str(&col_lines.join(",\n"));

    // ClickHouse: PRIMARY KEY must be a prefix of ORDER BY; skip inline PK
    // and encode it in the ENGINE clause below instead.
    if !pks.is_empty() && !matches!(target_db, DatabaseType::ClickHouse) {
        ddl.push_str(&format!(",\n  PRIMARY KEY ({})", pks.join(", ")));
    }

    ddl.push_str("\n)");

    if is_mysql_family {
        if let Some(comment) = table_comment {
            let trimmed = comment.trim();
            if !trimmed.is_empty() {
                ddl.push_str(&format!(" COMMENT='{}'", trimmed.replace('\'', "''")));
            }
        }
    }

    if matches!(target_db, DatabaseType::ClickHouse) {
        if pks.is_empty() {
            ddl.push_str(" ENGINE = MergeTree() ORDER BY tuple()");
        } else {
            ddl.push_str(&format!(" ENGINE = MergeTree() ORDER BY ({})", pks.join(", ")));
        }
    }

    ddl
}

/// Generate COMMENT ON COLUMN / ALTER TABLE COMMENT COLUMN / COMMENT ON TABLE
/// statements for databases that don't support inline comments in CREATE TABLE.
/// MySQL family uses inline syntax (handled in generate_create_table_ddl).
pub fn generate_comment_ddl(
    columns: &[db::ColumnInfo],
    table: &str,
    schema: &str,
    target_db: &DatabaseType,
    table_comment: Option<&str>,
) -> Vec<String> {
    if !(is_postgres_transfer_dialect(target_db)
        || matches!(target_db, DatabaseType::Oracle | DatabaseType::ClickHouse))
    {
        return Vec::new();
    }

    let full_table = qualified_table(table, schema, target_db, None);
    let mut statements = Vec::new();

    // Table-level comment first (PostgreSQL/Oracle only; ClickHouse doesn't support COMMENT ON TABLE)
    if is_postgres_transfer_dialect(target_db) || matches!(target_db, DatabaseType::Oracle) {
        if let Some(comment) = table_comment {
            let trimmed = comment.trim();
            if !trimmed.is_empty() {
                let escaped = trimmed.replace('\'', "''");
                statements.push(format!("COMMENT ON TABLE {full_table} IS '{escaped}'"));
            }
        }
    }

    for c in columns {
        if let Some(ref comment) = c.comment {
            let trimmed = comment.trim();
            if trimmed.is_empty() {
                continue;
            }
            let escaped = trimmed.replace('\'', "''");
            let qcol = quote_identifier(&c.name, target_db);

            match target_db {
                target_db if is_postgres_transfer_dialect(target_db) || matches!(target_db, DatabaseType::Oracle) => {
                    statements.push(format!("COMMENT ON COLUMN {full_table}.{qcol} IS '{escaped}'"));
                }
                DatabaseType::ClickHouse => {
                    statements.push(format!("ALTER TABLE {full_table} COMMENT COLUMN {qcol} '{escaped}'"));
                }
                _ => {}
            }
        }
    }

    statements
}

pub fn generate_insert(
    columns: &[String],
    rows: &[Vec<serde_json::Value>],
    table: &str,
    schema: &str,
    db_type: &DatabaseType,
) -> String {
    generate_insert_typed(columns, &vec![None; columns.len()], rows, table, schema, db_type, None)
}

pub fn generate_insert_typed(
    columns: &[String],
    column_types: &[Option<String>],
    rows: &[Vec<serde_json::Value>],
    table: &str,
    schema: &str,
    db_type: &DatabaseType,
    catalog: Option<&str>,
) -> String {
    if rows.is_empty() {
        return String::new();
    }

    let template = InsertSqlTemplate::new(columns, table, schema, db_type, catalog, false);
    let value_rows = value_rows_sql(rows, column_types, db_type, false);
    template.build(&value_rows)
}

#[derive(Debug)]
struct InsertSqlTemplate {
    standard_prefix: String,
    oracle_into_prefix: Option<String>,
}

impl InsertSqlTemplate {
    fn new(
        columns: &[String],
        table: &str,
        schema: &str,
        db_type: &DatabaseType,
        catalog: Option<&str>,
        overrides_postgres_system_values: bool,
    ) -> Self {
        let full_table = qualified_table(table, schema, db_type, catalog);
        let col_list = columns.iter().map(|column| quote_identifier(column, db_type)).collect::<Vec<_>>().join(", ");
        let overriding = if overrides_postgres_system_values && matches!(db_type, DatabaseType::Postgres) {
            " OVERRIDING SYSTEM VALUE"
        } else {
            ""
        };
        Self {
            standard_prefix: format!("INSERT INTO {full_table} ({col_list}){overriding} VALUES\n"),
            oracle_into_prefix: matches!(db_type, DatabaseType::Oracle)
                .then(|| format!("INTO {full_table} ({col_list}) VALUES ")),
        }
    }

    fn build(&self, value_rows: &[String]) -> String {
        if value_rows.is_empty() {
            return String::new();
        }
        if let Some(into_prefix) = self.oracle_into_prefix.as_deref().filter(|_| value_rows.len() > 1) {
            let mut sql = String::from("INSERT ALL\n");
            for (index, values) in value_rows.iter().enumerate() {
                if index > 0 {
                    sql.push('\n');
                }
                sql.push_str(into_prefix);
                sql.push_str(values);
            }
            sql.push_str("\nSELECT 1 FROM dual");
            return sql;
        }

        let mut sql = self.standard_prefix.clone();
        sql.push_str(&value_rows.join(",\n"));
        sql
    }

    fn statement_bytes(&self, value_rows_bytes: usize, row_count: usize, db_type: &DatabaseType) -> usize {
        if let Some(into_prefix) = self.oracle_into_prefix.as_deref().filter(|_| row_count > 1) {
            return sql_text_bytes("INSERT ALL\n", db_type)
                .saturating_add(sql_text_bytes(into_prefix, db_type).saturating_mul(row_count))
                .saturating_add(value_rows_bytes)
                .saturating_add(sql_text_bytes("\n", db_type).saturating_mul(row_count - 1))
                .saturating_add(sql_text_bytes("\nSELECT 1 FROM dual", db_type));
        }

        sql_text_bytes(&self.standard_prefix, db_type)
            .saturating_add(value_rows_bytes)
            .saturating_add(sql_text_bytes(",\n", db_type).saturating_mul(row_count.saturating_sub(1)))
    }
}

fn sql_text_bytes(sql: &str, db_type: &DatabaseType) -> usize {
    if matches!(db_type, DatabaseType::SqlServer) {
        sql.encode_utf16().count().saturating_mul(2)
    } else {
        sql.len()
    }
}

fn value_rows_sql(
    rows: &[Vec<serde_json::Value>],
    column_types: &[Option<String>],
    db_type: &DatabaseType,
    mysql_spatial_markers: bool,
) -> Vec<String> {
    let mut out = Vec::with_capacity(rows.len());
    for row in rows {
        let mut vals = Vec::with_capacity(row.len());
        for (index, v) in row.iter().enumerate() {
            let column_type = column_types.get(index).and_then(|value| value.as_deref());
            let value = if mysql_spatial_markers {
                crate::database_export::format_mysql_spatial_export_literal(v, Some(*db_type), column_type)
            } else {
                None
            }
            .unwrap_or_else(|| escape_value_typed(v, db_type, column_type));
            vals.push(value);
        }
        out.push(format!("({})", vals.join(", ")));
    }
    out
}

pub fn generate_upsert(
    columns: &[String],
    rows: &[Vec<serde_json::Value>],
    table: &str,
    schema: &str,
    db_type: &DatabaseType,
    pk_columns: &[String],
) -> String {
    generate_upsert_typed(columns, &vec![None; columns.len()], rows, table, schema, db_type, pk_columns, None)
}

pub fn generate_upsert_typed(
    columns: &[String],
    column_types: &[Option<String>],
    rows: &[Vec<serde_json::Value>],
    table: &str,
    schema: &str,
    db_type: &DatabaseType,
    pk_columns: &[String],
    catalog: Option<&str>,
) -> String {
    generate_upsert_typed_for_transfer(
        columns,
        column_types,
        rows,
        table,
        schema,
        db_type,
        pk_columns,
        catalog,
        false,
        false,
    )
}

#[allow(clippy::too_many_arguments)]
fn generate_upsert_typed_for_transfer(
    columns: &[String],
    column_types: &[Option<String>],
    rows: &[Vec<serde_json::Value>],
    table: &str,
    schema: &str,
    db_type: &DatabaseType,
    pk_columns: &[String],
    catalog: Option<&str>,
    overrides_postgres_system_values: bool,
    mysql_spatial_markers: bool,
) -> String {
    if rows.is_empty() || pk_columns.is_empty() {
        return String::new();
    }

    let full_table = qualified_table(table, schema, db_type, catalog);
    let col_list = columns.iter().map(|c| quote_identifier(c, db_type)).collect::<Vec<_>>().join(", ");

    let value_rows = value_rows_sql(rows, column_types, db_type, mysql_spatial_markers);

    let mut non_pk_columns = Vec::with_capacity(columns.len().saturating_sub(pk_columns.len()));
    for c in columns {
        if !pk_columns.contains(c) {
            non_pk_columns.push(c);
        }
    }

    match db_type {
        db_type
            if is_postgres_transfer_dialect(db_type)
                || matches!(db_type, DatabaseType::Sqlite | DatabaseType::CloudflareD1 | DatabaseType::DuckDb) =>
        {
            let pk_list = pk_columns.iter().map(|c| quote_identifier(c, db_type)).collect::<Vec<_>>().join(", ");
            let overriding = if overrides_postgres_system_values && matches!(db_type, DatabaseType::Postgres) {
                " OVERRIDING SYSTEM VALUE"
            } else {
                ""
            };
            let mut sql =
                format!("INSERT INTO {full_table} ({col_list}){overriding} VALUES\n{}", value_rows.join(",\n"));
            if non_pk_columns.is_empty() {
                sql.push_str(&format!("\nON CONFLICT ({pk_list}) DO NOTHING"));
            } else {
                let update_set = non_pk_columns
                    .iter()
                    .map(|c| {
                        let qc = quote_identifier(c, db_type);
                        format!("{qc} = EXCLUDED.{qc}")
                    })
                    .collect::<Vec<_>>()
                    .join(", ");
                sql.push_str(&format!("\nON CONFLICT ({pk_list}) DO UPDATE SET {update_set}"));
            }
            sql
        }
        DatabaseType::Mysql | DatabaseType::Doris | DatabaseType::StarRocks => {
            let mut sql = format!("INSERT INTO {full_table} ({col_list}) VALUES\n{}", value_rows.join(",\n"));
            if non_pk_columns.is_empty() {
                sql.push_str("\nON DUPLICATE KEY UPDATE ");
                let first_pk = quote_identifier(&pk_columns[0], db_type);
                sql.push_str(&format!("{first_pk} = {first_pk}"));
            } else {
                let update_set = non_pk_columns
                    .iter()
                    .map(|c| {
                        let qc = quote_identifier(c, db_type);
                        format!("{qc} = VALUES({qc})")
                    })
                    .collect::<Vec<_>>()
                    .join(", ");
                sql.push_str(&format!("\nON DUPLICATE KEY UPDATE {update_set}"));
            }
            sql
        }
        DatabaseType::SqlServer => {
            let src_col_list = columns.iter().map(|c| quote_identifier(c, db_type)).collect::<Vec<_>>().join(", ");
            let on_clause = pk_columns
                .iter()
                .map(|c| {
                    let qc = quote_identifier(c, db_type);
                    format!("target.{qc} = src.{qc}")
                })
                .collect::<Vec<_>>()
                .join(" AND ");

            let mut sql = format!(
                "MERGE INTO {full_table} AS target USING (VALUES\n{}\n) AS src ({src_col_list}) ON {on_clause}",
                value_rows.join(",\n")
            );

            if !non_pk_columns.is_empty() {
                let update_set = non_pk_columns
                    .iter()
                    .map(|c| {
                        let qc = quote_identifier(c, db_type);
                        format!("target.{qc} = src.{qc}")
                    })
                    .collect::<Vec<_>>()
                    .join(", ");
                sql.push_str(&format!("\nWHEN MATCHED THEN UPDATE SET {update_set}"));
            }

            let insert_cols = columns.iter().map(|c| quote_identifier(c, db_type)).collect::<Vec<_>>().join(", ");
            let insert_vals =
                columns.iter().map(|c| format!("src.{}", quote_identifier(c, db_type))).collect::<Vec<_>>().join(", ");
            sql.push_str(&format!("\nWHEN NOT MATCHED THEN INSERT ({insert_cols}) VALUES ({insert_vals});"));
            sql
        }
        DatabaseType::Oracle => {
            let mut using_rows = Vec::with_capacity(rows.len());
            for row in rows {
                let mut vals = Vec::with_capacity(row.len().min(columns.len()));
                for (index, (v, c)) in row.iter().zip(columns.iter()).enumerate() {
                    vals.push(format!(
                        "{} AS {}",
                        escape_value_typed(v, db_type, column_types.get(index).and_then(|value| value.as_deref())),
                        quote_identifier(c, db_type)
                    ));
                }
                using_rows.push(format!("SELECT {} FROM dual", vals.join(", ")));
            }

            let on_clause = pk_columns
                .iter()
                .map(|c| {
                    let qc = quote_identifier(c, db_type);
                    format!("t.{qc} = s.{qc}")
                })
                .collect::<Vec<_>>()
                .join(" AND ");

            let mut sql =
                format!("MERGE INTO {full_table} t USING ({}) s ON ({on_clause})", using_rows.join(" UNION ALL "));

            if !non_pk_columns.is_empty() {
                let update_set = non_pk_columns
                    .iter()
                    .map(|c| {
                        let qc = quote_identifier(c, db_type);
                        format!("t.{qc} = s.{qc}")
                    })
                    .collect::<Vec<_>>()
                    .join(", ");
                sql.push_str(&format!("\nWHEN MATCHED THEN UPDATE SET {update_set}"));
            }

            let insert_cols = columns.iter().map(|c| quote_identifier(c, db_type)).collect::<Vec<_>>().join(", ");
            let insert_vals =
                columns.iter().map(|c| format!("s.{}", quote_identifier(c, db_type))).collect::<Vec<_>>().join(", ");
            sql.push_str(&format!("\nWHEN NOT MATCHED THEN INSERT ({insert_cols}) VALUES ({insert_vals})"));
            sql
        }
        _ => {
            let template = InsertSqlTemplate::new(columns, table, schema, db_type, catalog, false);
            template.build(&value_rows_sql(rows, column_types, db_type, mysql_spatial_markers))
        }
    }
}

fn max_transfer_write_rows(db_type: &DatabaseType, mode: &TransferMode) -> usize {
    match (db_type, mode) {
        (DatabaseType::SqlServer, TransferMode::Append | TransferMode::Overwrite) => MAX_SQLSERVER_INSERT_ROWS,
        (DatabaseType::Hive, _) => 500,
        (DatabaseType::Oracle, TransferMode::Append | TransferMode::Overwrite) => MAX_ORACLE_INSERT_ALL_ROWS,
        (DatabaseType::Oracle, TransferMode::Upsert) => MAX_ORACLE_MERGE_ROWS,
        _ => usize::MAX,
    }
}

fn is_oceanbase_mysql_profile(db_type: &DatabaseType, driver_profile: Option<&str>) -> bool {
    matches!(db_type, DatabaseType::Mysql)
        && driver_profile.is_some_and(|profile| profile.eq_ignore_ascii_case("oceanbase"))
}

fn contains_oceanbase_mysql_table_options(sql: &str) -> bool {
    let (sql_without_literals_or_comments, _) = protect_sql_literals(sql, true);
    OCEANBASE_MYSQL_TABLE_OPTION_RE.is_match(&sql_without_literals_or_comments)
}

fn mysql_ddl_collation_names(sql: &str) -> Vec<String> {
    let mut names = Vec::new();
    map_mysql_ddl_code_spans(sql, |code| {
        for captures in MYSQL_COLLATE_CLAUSE_RE.captures_iter(code) {
            let name = captures[1].to_string();
            if !names.iter().any(|existing: &String| existing.eq_ignore_ascii_case(&name)) {
                names.push(name);
            }
        }
        String::new()
    });
    names
}

fn remove_unsupported_mysql_collations(sql: &str, supported: &HashSet<String>) -> String {
    let supported = supported.iter().map(|name| name.to_ascii_lowercase()).collect::<HashSet<_>>();
    map_mysql_ddl_code_spans(sql, |code| {
        MYSQL_COLLATE_CLAUSE_RE
            .replace_all(code, |captures: &regex::Captures| {
                if supported.contains(&captures[1].to_ascii_lowercase()) {
                    captures[0].to_string()
                } else {
                    String::new()
                }
            })
            .to_string()
    })
}

fn mysql_collations_for_transfer_ddl_recovery(
    sql: &str,
    error: &str,
    target_db_type: &DatabaseType,
    reused_source_ddl: bool,
) -> Option<Vec<String>> {
    if !reused_source_ddl
        || !matches!(target_db_type, DatabaseType::Mysql)
        || !error.to_ascii_lowercase().contains("unknown collation")
        || !sql.trim_start().to_ascii_uppercase().starts_with("CREATE TABLE ")
    {
        return None;
    }
    let names = mysql_ddl_collation_names(sql);
    (!names.is_empty()).then_some(names)
}

fn can_reuse_source_table_ddl(
    source_db_type: &DatabaseType,
    target_db_type: &DatabaseType,
    source_driver_profile: Option<&str>,
    target_driver_profile: Option<&str>,
    preserves_target_table_name: bool,
) -> bool {
    if is_oceanbase_mysql_profile(source_db_type, source_driver_profile)
        && !is_oceanbase_mysql_profile(target_db_type, target_driver_profile)
    {
        return false;
    }

    preserves_target_table_name
        && !matches!(target_db_type, DatabaseType::ClickHouse)
        && (source_db_type == target_db_type
            || (is_mysql_family_target(source_db_type) && is_mysql_family_target(target_db_type))
            || (is_postgres_family_target(source_db_type) && is_postgres_family_target(target_db_type)))
}

fn rewrite_transfer_source_table_ddl(
    sql: &str,
    source_schema: &str,
    target_schema: &str,
    source_db_type: &DatabaseType,
    target_db_type: &DatabaseType,
) -> String {
    if is_postgres_family_target(source_db_type) && is_postgres_family_target(target_db_type) {
        rewrite_postgres_schema_qualified_references(sql, source_schema, target_schema)
    } else {
        sql.to_string()
    }
}

fn mysql_spatial_transfer_select_sql(
    sql: String,
    columns: &[String],
    column_types: &[Option<String>],
    source_db_type: &DatabaseType,
    target_db_type: &DatabaseType,
) -> (String, bool) {
    let has_spatial_columns = column_types
        .iter()
        .any(|column_type| column_type.as_deref().is_some_and(crate::database_export::is_mysql_spatial_export_type));
    if !matches!((source_db_type, target_db_type), (DatabaseType::Mysql, DatabaseType::Mysql)) || !has_spatial_columns {
        return (sql, false);
    }
    (crate::database_export::replace_database_export_select_list(sql, columns, column_types, source_db_type), true)
}

#[allow(clippy::too_many_arguments)]
fn generate_transfer_write_sql(
    mode: &TransferMode,
    columns: &[String],
    column_types: &[Option<String>],
    rows: &[Vec<serde_json::Value>],
    table: &str,
    schema: &str,
    db_type: &DatabaseType,
    pk_columns: &[String],
    catalog: Option<&str>,
    overrides_postgres_system_values: bool,
    mysql_spatial_markers: bool,
) -> String {
    match mode {
        TransferMode::Upsert => generate_upsert_typed_for_transfer(
            columns,
            column_types,
            rows,
            table,
            schema,
            db_type,
            pk_columns,
            catalog,
            overrides_postgres_system_values,
            mysql_spatial_markers,
        ),
        _ => {
            if rows.is_empty() {
                return String::new();
            }
            let template =
                InsertSqlTemplate::new(columns, table, schema, db_type, catalog, overrides_postgres_system_values);
            template.build(&value_rows_sql(rows, column_types, db_type, mysql_spatial_markers))
        }
    }
}

#[allow(clippy::too_many_arguments)]
pub(crate) fn generate_insert_typed_sql_batches(
    columns: &[String],
    column_types: &[Option<String>],
    rows: &[Vec<serde_json::Value>],
    table: &str,
    schema: &str,
    db_type: &DatabaseType,
    catalog: Option<&str>,
    limits: SqlBatchLimits,
) -> Result<Vec<(String, usize)>, String> {
    generate_insert_typed_sql_batches_for_transfer(
        columns,
        column_types,
        rows,
        table,
        schema,
        db_type,
        catalog,
        limits,
        false,
        false,
    )
}

#[allow(clippy::too_many_arguments)]
fn generate_insert_typed_sql_batches_for_transfer(
    columns: &[String],
    column_types: &[Option<String>],
    rows: &[Vec<serde_json::Value>],
    table: &str,
    schema: &str,
    db_type: &DatabaseType,
    catalog: Option<&str>,
    limits: SqlBatchLimits,
    overrides_postgres_system_values: bool,
    mysql_spatial_markers: bool,
) -> Result<Vec<(String, usize)>, String> {
    if rows.is_empty() {
        return Ok(Vec::new());
    }

    let max_rows = limits.max_rows.max(1).min(match db_type {
        DatabaseType::SqlServer => MAX_SQLSERVER_INSERT_ROWS,
        DatabaseType::Oracle => MAX_ORACLE_INSERT_ALL_ROWS,
        _ => usize::MAX,
    });
    let target_sql_bytes = limits.target_sql_bytes.max(1);
    let batch_sql_bytes = limits.hard_sql_bytes.map_or(target_sql_bytes, |hard| target_sql_bytes.min(hard));
    let template = InsertSqlTemplate::new(columns, table, schema, db_type, catalog, overrides_postgres_system_values);
    let value_rows = value_rows_sql(rows, column_types, db_type, mysql_spatial_markers);
    let value_row_bytes = value_rows.iter().map(|row| sql_text_bytes(row, db_type)).collect::<Vec<_>>();
    let mut statements = Vec::new();
    let mut start = 0usize;

    while start < value_rows.len() {
        let mut end = start;
        let mut rows_bytes = 0usize;
        while end < value_rows.len() && end - start < max_rows {
            let single_row_bytes = template.statement_bytes(value_row_bytes[end], 1, db_type);
            if let Some(hard_sql_bytes) = limits.hard_sql_bytes {
                if single_row_bytes > hard_sql_bytes {
                    return Err(format!(
                        "SQL batch row {} requires {} bytes and exceeds the {} byte hard limit",
                        end + 1,
                        single_row_bytes,
                        hard_sql_bytes
                    ));
                }
            }
            let candidate_rows_bytes = rows_bytes.saturating_add(value_row_bytes[end]);
            let candidate_row_count = end - start + 1;
            let candidate_bytes = template.statement_bytes(candidate_rows_bytes, candidate_row_count, db_type);
            if candidate_row_count > 1 && candidate_bytes > batch_sql_bytes {
                break;
            }
            rows_bytes = candidate_rows_bytes;
            end += 1;
        }

        statements.push((template.build(&value_rows[start..end]), end - start));
        start = end;
    }

    Ok(statements)
}

#[allow(clippy::too_many_arguments)]
fn generate_transfer_write_sql_batches(
    mode: &TransferMode,
    columns: &[String],
    column_types: &[Option<String>],
    rows: &[Vec<serde_json::Value>],
    table: &str,
    schema: &str,
    db_type: &DatabaseType,
    pk_columns: &[String],
    catalog: Option<&str>,
    overrides_postgres_system_values: bool,
    mysql_spatial_markers: bool,
) -> Result<Vec<String>, String> {
    if rows.is_empty() {
        return Ok(Vec::new());
    }

    if matches!(mode, TransferMode::Append | TransferMode::Overwrite) {
        return Ok(generate_insert_typed_sql_batches_for_transfer(
            columns,
            column_types,
            rows,
            table,
            schema,
            db_type,
            catalog,
            SqlBatchLimits::for_database(db_type, max_transfer_write_rows(db_type, mode)),
            overrides_postgres_system_values,
            mysql_spatial_markers,
        )?
        .into_iter()
        .map(|(sql, _)| sql)
        .collect());
    }

    let max_rows = max_transfer_write_rows(db_type, mode);
    let max_sql_bytes = match db_type {
        DatabaseType::CloudflareD1 => crate::db::cloudflare_d1::MAX_SQL_STATEMENT_BYTES,
        _ => MAX_TRANSFER_WRITE_SQL_BYTES,
    };
    let mut statements = Vec::new();
    let mut start = 0;

    while start < rows.len() {
        let mut end = start + 1;
        let mut accepted = generate_transfer_write_sql(
            mode,
            columns,
            column_types,
            &rows[start..end],
            table,
            schema,
            db_type,
            pk_columns,
            catalog,
            overrides_postgres_system_values,
            mysql_spatial_markers,
        );

        while end < rows.len() && end - start < max_rows {
            let candidate = generate_transfer_write_sql(
                mode,
                columns,
                column_types,
                &rows[start..=end],
                table,
                schema,
                db_type,
                pk_columns,
                catalog,
                overrides_postgres_system_values,
                mysql_spatial_markers,
            );
            if candidate.len() > max_sql_bytes && !accepted.is_empty() {
                break;
            }
            accepted = candidate;
            end += 1;
        }

        if !accepted.is_empty() {
            statements.push(accepted);
        }
        start = end;
    }

    Ok(statements)
}

pub fn pagination_sql(
    columns: &[String],
    table: &str,
    schema: &str,
    db_type: &DatabaseType,
    offset: u64,
    limit: usize,
) -> String {
    let full_table = qualified_table(table, schema, db_type, None);
    let col_list = columns.iter().map(|c| quote_identifier(c, db_type)).collect::<Vec<_>>().join(", ");

    match db_type {
        DatabaseType::Oracle => {
            let base_sql = format!("SELECT {col_list} FROM {full_table}");
            oracle_rownum_page_sql(&col_list, base_sql, offset, limit)
        }
        DatabaseType::SqlServer | DatabaseType::Dameng => {
            format!(
                "SELECT {col_list} FROM {full_table} ORDER BY (SELECT NULL) OFFSET {offset} ROWS FETCH NEXT {limit} ROWS ONLY"
            )
        }
        DatabaseType::Questdb => {
            let upper_bound = offset + limit as u64;
            format!("SELECT {col_list} FROM {full_table} LIMIT {offset}, {upper_bound}")
        }
        _ => {
            format!("SELECT {col_list} FROM {full_table} LIMIT {limit} OFFSET {offset}")
        }
    }
}

pub fn pagination_sql_with_order(
    columns: &[String],
    table: &str,
    schema: &str,
    db_type: &DatabaseType,
    offset: u64,
    limit: usize,
    order_by_columns: &[String],
    catalog: Option<&str>,
) -> String {
    let full_table = qualified_table(table, schema, db_type, catalog);
    let col_list = columns.iter().map(|c| quote_identifier(c, db_type)).collect::<Vec<_>>().join(", ");
    let order_expression = postgres_order_by_expression(order_by_columns, db_type);

    match db_type {
        DatabaseType::Oracle => {
            let order_by = order_expression.map(|value| format!(" ORDER BY {value}")).unwrap_or_default();
            let base_sql = format!("SELECT {col_list} FROM {full_table}{order_by}");
            oracle_rownum_page_sql(&col_list, base_sql, offset, limit)
        }
        DatabaseType::SqlServer | DatabaseType::Dameng => {
            let order_by = order_expression.unwrap_or_else(|| "(SELECT NULL)".to_string());
            format!(
                "SELECT {col_list} FROM {full_table} ORDER BY {order_by} OFFSET {offset} ROWS FETCH NEXT {limit} ROWS ONLY"
            )
        }
        DatabaseType::Questdb => {
            let upper_bound = offset + limit as u64;
            let order_by = order_expression.map(|value| format!(" ORDER BY {value}")).unwrap_or_default();
            format!("SELECT {col_list} FROM {full_table}{order_by} LIMIT {offset}, {upper_bound}")
        }
        _ => {
            let order_by = order_expression.map(|value| format!(" ORDER BY {value}")).unwrap_or_default();
            format!("SELECT {col_list} FROM {full_table}{order_by} LIMIT {limit} OFFSET {offset}")
        }
    }
}

#[allow(clippy::too_many_arguments)]
pub fn pagination_sql_with_filter_order(
    columns: &[String],
    table: &str,
    schema: &str,
    db_type: &DatabaseType,
    offset: u64,
    limit: usize,
    where_input: Option<&str>,
    order_by: Option<&str>,
    default_order_columns: &[String],
) -> String {
    pagination_sql_with_filter_order_and_identifier_quote(
        columns,
        table,
        schema,
        db_type,
        offset,
        limit,
        where_input,
        order_by,
        default_order_columns,
        None,
    )
}

#[allow(clippy::too_many_arguments)]
pub fn pagination_sql_with_filter_order_and_identifier_quote(
    columns: &[String],
    table: &str,
    schema: &str,
    db_type: &DatabaseType,
    offset: u64,
    limit: usize,
    where_input: Option<&str>,
    order_by: Option<&str>,
    default_order_columns: &[String],
    identifier_quote: Option<&str>,
) -> String {
    let full_table = qualified_table_with_identifier_quote(table, schema, db_type, None, identifier_quote);
    let col_list = columns
        .iter()
        .map(|c| quote_identifier_with_identifier_quote(c, db_type, identifier_quote))
        .collect::<Vec<_>>()
        .join(", ");
    let predicate = crate::sql_dialect::normalize_where_input(where_input);
    let where_clause = if predicate.is_empty() { String::new() } else { format!(" WHERE ({predicate})") };
    let order_expression =
        order_by.map(str::trim).filter(|value| !value.is_empty()).map(str::to_string).or_else(|| {
            postgres_order_by_expression_with_identifier_quote(default_order_columns, db_type, identifier_quote)
        });

    match db_type {
        DatabaseType::Oracle => {
            let order_by = order_expression.map(|value| format!(" ORDER BY {value}")).unwrap_or_default();
            let base_sql = format!("SELECT {col_list} FROM {full_table}{where_clause}{order_by}");
            oracle_rownum_page_sql(&col_list, base_sql, offset, limit)
        }
        DatabaseType::SqlServer | DatabaseType::Dameng => {
            let order_by = order_expression.unwrap_or_else(|| "(SELECT NULL)".to_string());
            format!(
                "SELECT {col_list} FROM {full_table}{where_clause} ORDER BY {order_by} OFFSET {offset} ROWS FETCH NEXT {limit} ROWS ONLY"
            )
        }
        DatabaseType::Questdb => {
            let upper_bound = offset + limit as u64;
            let order_by = order_expression.map(|value| format!(" ORDER BY {value}")).unwrap_or_default();
            format!("SELECT {col_list} FROM {full_table}{where_clause}{order_by} LIMIT {offset}, {upper_bound}")
        }
        _ => {
            let order_by = order_expression.map(|value| format!(" ORDER BY {value}")).unwrap_or_default();
            format!("SELECT {col_list} FROM {full_table}{where_clause}{order_by} LIMIT {limit} OFFSET {offset}")
        }
    }
}

pub fn count_sql(table: &str, schema: &str, db_type: &DatabaseType, catalog: Option<&str>) -> String {
    count_sql_with_where(table, schema, db_type, None, catalog)
}

pub fn count_sql_with_where(
    table: &str,
    schema: &str,
    db_type: &DatabaseType,
    where_input: Option<&str>,
    catalog: Option<&str>,
) -> String {
    count_sql_with_where_and_identifier_quote(table, schema, db_type, where_input, catalog, None)
}

pub fn count_sql_with_where_and_identifier_quote(
    table: &str,
    schema: &str,
    db_type: &DatabaseType,
    where_input: Option<&str>,
    catalog: Option<&str>,
    identifier_quote: Option<&str>,
) -> String {
    let full_table = qualified_table_with_identifier_quote(table, schema, db_type, catalog, identifier_quote);
    let predicate = crate::sql_dialect::normalize_where_input(where_input);
    let where_clause = if predicate.is_empty() { String::new() } else { format!(" WHERE ({predicate})") };
    format!("SELECT COUNT(*) FROM {full_table}{where_clause}")
}

pub fn keyset_pagination_sql(
    columns: &[String],
    table: &str,
    schema: &str,
    db_type: &DatabaseType,
    primary_keys: &[String],
    last_pk_values: &[serde_json::Value],
    limit: usize,
) -> String {
    keyset_pagination_sql_with_identifier_quote(
        columns,
        table,
        schema,
        db_type,
        primary_keys,
        last_pk_values,
        limit,
        None,
    )
}

#[allow(clippy::too_many_arguments)]
pub fn keyset_pagination_sql_with_identifier_quote(
    columns: &[String],
    table: &str,
    schema: &str,
    db_type: &DatabaseType,
    primary_keys: &[String],
    last_pk_values: &[serde_json::Value],
    limit: usize,
    identifier_quote: Option<&str>,
) -> String {
    let full_table = qualified_table_with_identifier_quote(table, schema, db_type, None, identifier_quote);
    let col_list = columns
        .iter()
        .map(|c| quote_identifier_with_identifier_quote(c, db_type, identifier_quote))
        .collect::<Vec<_>>()
        .join(", ");
    let order = primary_keys
        .iter()
        .map(|pk| format!("{} ASC", quote_identifier_with_identifier_quote(pk, db_type, identifier_quote)))
        .collect::<Vec<_>>()
        .join(", ");

    let where_clause = keyset_where_clause(primary_keys, last_pk_values, db_type, identifier_quote);

    match db_type {
        DatabaseType::Oracle => {
            let base_sql = format!("SELECT {col_list} FROM {full_table}{where_clause} ORDER BY {order}");
            oracle_rownum_page_sql(&col_list, base_sql, 0, limit)
        }
        DatabaseType::SqlServer | DatabaseType::Dameng => {
            format!(
                "SELECT {col_list} FROM {full_table}{where_clause} ORDER BY {order} OFFSET 0 ROWS FETCH NEXT {limit} ROWS ONLY"
            )
        }
        _ => {
            format!("SELECT {col_list} FROM {full_table}{where_clause} ORDER BY {order} LIMIT {limit}")
        }
    }
}

fn keyset_where_clause(
    primary_keys: &[String],
    last_pk_values: &[serde_json::Value],
    db_type: &DatabaseType,
    identifier_quote: Option<&str>,
) -> String {
    if primary_keys.is_empty() || last_pk_values.is_empty() {
        return String::new();
    }

    let quoted_keys = primary_keys
        .iter()
        .map(|pk| quote_identifier_with_identifier_quote(pk, db_type, identifier_quote))
        .collect::<Vec<_>>();
    let literals = last_pk_values.iter().map(|v| value_to_sql_literal(v, db_type)).collect::<Vec<_>>();
    let comparison_count = quoted_keys.len().min(literals.len());
    if comparison_count == 0 {
        return String::new();
    }

    let mut clauses = Vec::with_capacity(comparison_count);
    for index in 0..comparison_count {
        let mut parts = Vec::with_capacity(index + 1);
        for prefix_index in 0..index {
            parts.push(format!("{} = {}", quoted_keys[prefix_index], literals[prefix_index]));
        }
        parts.push(format!("{} > {}", quoted_keys[index], literals[index]));
        if parts.len() == 1 {
            clauses.push(parts.remove(0));
        } else {
            clauses.push(format!("({})", parts.join(" AND ")));
        }
    }

    if clauses.len() == 1 {
        format!(" WHERE {}", clauses[0])
    } else {
        format!(" WHERE ({})", clauses.join(" OR "))
    }
}

fn value_to_sql_literal(value: &serde_json::Value, _db_type: &DatabaseType) -> String {
    match value {
        serde_json::Value::Null => "NULL".to_string(),
        serde_json::Value::Bool(b) => {
            if *b {
                "TRUE".to_string()
            } else {
                "FALSE".to_string()
            }
        }
        serde_json::Value::Number(n) => n.to_string(),
        serde_json::Value::String(s) => quote_string_literal(s),
        _ => quote_string_literal(&value.to_string()),
    }
}

fn is_mongodb_transfer_type(db_type: &DatabaseType) -> bool {
    matches!(db_type, DatabaseType::MongoDb)
}

fn mongo_transfer_document_fields(documents: &[serde_json::Value]) -> Vec<String> {
    let mut fields = Vec::new();
    let mut seen = HashSet::new();
    for document in documents {
        let Some(object) = document.as_object() else {
            continue;
        };
        for key in object.keys() {
            if seen.insert(key.clone()) {
                fields.push(key.clone());
            }
        }
    }
    fields
}

fn mongo_documents_to_rows(documents: &[serde_json::Value], columns: &[String]) -> Vec<Vec<serde_json::Value>> {
    documents
        .iter()
        .map(|document| {
            let object = document.as_object();
            columns
                .iter()
                .map(|column| object.and_then(|values| values.get(column)).cloned().unwrap_or(serde_json::Value::Null))
                .collect()
        })
        .collect()
}

fn sql_rows_to_mongo_documents(columns: &[String], rows: &[Vec<serde_json::Value>]) -> Vec<serde_json::Value> {
    rows.iter()
        .map(|row| {
            let mut document = serde_json::Map::new();
            for (index, column) in columns.iter().enumerate() {
                document.insert(column.clone(), row.get(index).cloned().unwrap_or(serde_json::Value::Null));
            }
            serde_json::Value::Object(document)
        })
        .collect()
}

async fn find_mongo_documents_extended_json(
    state: &AppState,
    connection_id: &str,
    database: &str,
    collection: &str,
    offset: u64,
    batch_size: usize,
) -> Result<MongoDocumentResult, String> {
    crate::mongo_ops::mongo_find_documents_extended_json_core(
        state,
        connection_id,
        database,
        collection,
        offset,
        batch_size as i64,
        None,
        None,
        Some(r#"{"_id":1}"#),
    )
    .await
}

async fn find_mongo_documents_for_rows(
    state: &AppState,
    connection_id: &str,
    database: &str,
    collection: &str,
    offset: u64,
    batch_size: usize,
) -> Result<MongoDocumentResult, String> {
    crate::mongo_ops::mongo_find_documents_core(
        state,
        connection_id,
        database,
        collection,
        offset,
        batch_size as i64,
        None,
        None,
        Some(r#"{"_id":1}"#),
        None,
    )
    .await
}

async fn insert_mongo_documents_for_transfer(
    state: &AppState,
    connection_id: &str,
    database: &str,
    collection: &str,
    documents: &[serde_json::Value],
) -> Result<u64, String> {
    if documents.is_empty() {
        return Ok(0);
    }
    let docs_json = serde_json::to_string(documents).map_err(|e| format!("Failed to encode MongoDB documents: {e}"))?;
    match crate::mongo_ops::mongo_insert_documents_core(state, connection_id, database, collection, &docs_json).await {
        Ok(count) => Ok(count),
        Err(error) if error.to_ascii_lowercase().contains("legacy agent") => {
            let mut inserted = 0;
            for document in documents {
                let doc_json =
                    serde_json::to_string(document).map_err(|e| format!("Failed to encode MongoDB document: {e}"))?;
                crate::mongo_ops::mongo_insert_document_core(state, connection_id, database, collection, &doc_json)
                    .await?;
                inserted += 1;
            }
            Ok(inserted)
        }
        Err(error) => Err(error),
    }
}

async fn insert_mongo_documents_extended_json_for_transfer(
    state: &AppState,
    connection_id: &str,
    database: &str,
    collection: &str,
    documents: &[serde_json::Value],
) -> Result<u64, String> {
    if documents.is_empty() {
        return Ok(0);
    }
    let docs_json = serde_json::to_string(documents).map_err(|e| format!("Failed to encode MongoDB documents: {e}"))?;
    match crate::mongo_ops::mongo_insert_documents_extended_json_core(
        state,
        connection_id,
        database,
        collection,
        &docs_json,
    )
    .await
    {
        Ok(count) => Ok(count),
        Err(error) if error.to_ascii_lowercase().contains("legacy agent") => {
            insert_mongo_documents_for_transfer(state, connection_id, database, collection, documents).await
        }
        Err(error) => Err(error),
    }
}

async fn overwrite_mongo_collection_for_transfer(
    state: &AppState,
    connection_id: &str,
    database: &str,
    collection: &str,
) -> Result<(), String> {
    crate::mongo_ops::mongo_delete_documents_core(state, connection_id, database, collection, "{}", true)
        .await
        .map(|_| ())
}

fn mongo_value_column_type(value: Option<&serde_json::Value>) -> String {
    match value {
        Some(serde_json::Value::Bool(_)) => "boolean".to_string(),
        Some(serde_json::Value::Number(number)) if number.is_i64() || number.is_u64() => "bigint".to_string(),
        Some(serde_json::Value::Number(_)) => "double".to_string(),
        Some(serde_json::Value::Array(_) | serde_json::Value::Object(_)) => "json".to_string(),
        _ => "text".to_string(),
    }
}

fn mongo_columns_from_documents(documents: &[serde_json::Value]) -> Vec<db::ColumnInfo> {
    mongo_transfer_document_fields(documents)
        .into_iter()
        .map(|name| {
            let sample =
                documents.iter().filter_map(|document| document.as_object()?.get(&name)).find(|value| !value.is_null());
            db::ColumnInfo {
                name,
                data_type: mongo_value_column_type(sample),
                is_nullable: true,
                column_default: None,
                is_primary_key: false,
                extra: None,
                comment: None,
                numeric_precision: None,
                numeric_scale: None,
                character_maximum_length: None,
                enum_values: None,
                ..Default::default()
            }
        })
        .collect()
}

pub async fn execute_on_pool(state: &AppState, pool_key: &str, sql: &str) -> Result<db::QueryResult, String> {
    execute_on_pool_with_options(state, pool_key, sql, None, TransferExecutionSafety::WriteNoReplay).await
}

pub async fn execute_read_on_pool(state: &AppState, pool_key: &str, sql: &str) -> Result<db::QueryResult, String> {
    execute_read_on_pool_with_max_rows(state, pool_key, sql, None).await
}

pub async fn execute_read_on_pool_with_max_rows(
    state: &AppState,
    pool_key: &str,
    sql: &str,
    max_rows: Option<usize>,
) -> Result<db::QueryResult, String> {
    execute_on_pool_with_options(state, pool_key, sql, max_rows, TransferExecutionSafety::ReadOnlyRetryable).await
}

async fn execute_transfer_ddl_on_pool(
    state: &AppState,
    pool_key: &str,
    sql: &str,
    db_type: &DatabaseType,
) -> Result<(), String> {
    for statement in transfer_ddl_statements(sql, db_type) {
        execute_on_pool(state, pool_key, &statement).await?;
    }
    Ok(())
}

async fn supported_mysql_transfer_collations(
    state: &AppState,
    pool_key: &str,
    names: &[String],
) -> Result<HashSet<String>, String> {
    let names = names.iter().map(|name| quote_string_literal(name)).collect::<Vec<_>>().join(", ");
    let sql = format!("SELECT COLLATION_NAME FROM information_schema.COLLATIONS WHERE COLLATION_NAME IN ({names})");
    let result = execute_on_pool(state, pool_key, &sql).await?;
    Ok(result.rows.iter().filter_map(|row| json_string_cell(row, 0)).map(|name| name.to_ascii_lowercase()).collect())
}

async fn execute_transfer_create_table_ddl_on_pool(
    state: &AppState,
    pool_key: &str,
    sql: &str,
    db_type: &DatabaseType,
    reused_source_ddl: bool,
) -> Result<(), String> {
    let original_error = match execute_transfer_ddl_on_pool(state, pool_key, sql, db_type).await {
        Ok(()) => return Ok(()),
        Err(error) => error,
    };
    let Some(collations) = mysql_collations_for_transfer_ddl_recovery(sql, &original_error, db_type, reused_source_ddl)
    else {
        return Err(original_error);
    };
    let supported = supported_mysql_transfer_collations(state, pool_key, &collations)
        .await
        .map_err(|error| format!("{original_error}; failed to inspect target MySQL collations: {error}"))?;
    let rewritten = remove_unsupported_mysql_collations(sql, &supported);
    if rewritten == sql {
        return Err(format!("{original_error}; target MySQL reports all referenced collations as supported"));
    }

    let unsupported =
        collations.iter().filter(|name| !supported.contains(&name.to_ascii_lowercase())).cloned().collect::<Vec<_>>();
    log::warn!("[transfer] retrying target table DDL without unsupported MySQL collations: {}", unsupported.join(", "));
    execute_transfer_ddl_on_pool(state, pool_key, &rewritten, db_type)
        .await
        .map_err(|error| format!("{original_error}; retry without unsupported MySQL collations failed: {error}"))
}

fn transfer_table_already_exists_error(error: &str) -> bool {
    let lower = error.to_ascii_lowercase();
    lower.contains("already exists")
        || lower.contains("there is already")
        || lower.contains("duplicate_table")
        || lower.contains("42p07")
        || error.contains("已经存在")
        || error.contains("已存在")
}

fn transfer_create_table_created(result: Result<(), String>, error_prefix: &str) -> Result<bool, String> {
    match result {
        Ok(_) => Ok(true),
        Err(e) if transfer_table_already_exists_error(&e) => Ok(false),
        Err(e) => Err(format!("{error_prefix}: {e}")),
    }
}

fn transfer_ddl_statements(sql: &str, db_type: &DatabaseType) -> Vec<String> {
    if is_postgres_transfer_dialect(db_type) {
        let statements = split_sql_statements(sql);
        if statements.is_empty() {
            vec![sql.trim().to_string()]
        } else {
            statements
                .into_iter()
                .map(|statement| sanitize_postgres_transfer_ddl_statement(&statement))
                .filter(|statement| !is_postgres_post_table_index_statement(statement))
                .collect()
        }
    } else if matches!(db_type, DatabaseType::Dameng) {
        let statements = split_sql_statements_for_database(sql, *db_type);
        if statements.is_empty() {
            vec![sql.trim().to_string()]
        } else {
            statements
        }
    } else {
        vec![sql.to_string()]
    }
}

fn sanitize_postgres_transfer_ddl_statement(statement: &str) -> String {
    if !statement.trim_start().to_ascii_uppercase().starts_with("CREATE TABLE ") {
        return statement.to_string();
    }

    let mut lines: Vec<String> = Vec::new();
    for line in statement.lines() {
        if line.to_ascii_uppercase().contains(" FOREIGN KEY ") {
            if let Some(previous) = lines.last_mut() {
                let trimmed_len = previous.trim_end_matches(char::is_whitespace).len();
                if previous[..trimmed_len].ends_with(',') {
                    previous.truncate(trimmed_len - 1);
                }
            }
            continue;
        }
        lines.push(line.to_string());
    }
    lines.join("\n")
}

fn is_postgres_post_table_index_statement(statement: &str) -> bool {
    let normalized = statement.trim_start().to_ascii_uppercase();
    normalized.starts_with("CREATE INDEX ")
        || normalized.starts_with("CREATE UNIQUE INDEX ")
        || normalized.starts_with("COMMENT ON INDEX ")
}

pub async fn execute_on_pool_with_max_rows(
    state: &AppState,
    pool_key: &str,
    sql: &str,
    max_rows: Option<usize>,
) -> Result<db::QueryResult, String> {
    execute_on_pool_with_options(state, pool_key, sql, max_rows, TransferExecutionSafety::WriteNoReplay).await
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum TransferExecutionSafety {
    ReadOnlyRetryable,
    WriteNoReplay,
}

fn transfer_pool_error_action(
    safety: TransferExecutionSafety,
    db_type: Option<DatabaseType>,
    err: &str,
) -> PoolErrorAction {
    match (safety, pool_error_action(db_type, err)) {
        (TransferExecutionSafety::WriteNoReplay, PoolErrorAction::ReconnectAndRetry) => PoolErrorAction::Discard,
        (_, action) => action,
    }
}

async fn transfer_pool_context(
    state: &AppState,
    pool_key: &str,
) -> (Option<String>, Option<String>, Option<DatabaseType>) {
    let configs = state.configs.read().await;
    let config = config_for_pool_key(pool_key, &configs);
    (
        config.map(|config| config.id.clone()),
        database_from_pool_key(pool_key).map(str::to_string),
        config.map(|config| config.db_type),
    )
}

fn client_session_id_from_pool_key(pool_key: &str) -> Option<&str> {
    pool_key.split_once(":session:").map(|(_, session)| session).filter(|session| !session.is_empty())
}

async fn execute_on_pool_with_options(
    state: &AppState,
    pool_key: &str,
    sql: &str,
    max_rows: Option<usize>,
    safety: TransferExecutionSafety,
) -> Result<db::QueryResult, String> {
    let (connection_id, database, db_type) = transfer_pool_context(state, pool_key).await;
    let client_session_id = client_session_id_from_pool_key(pool_key).map(str::to_string);
    let mut current_pool_key = pool_key.to_string();

    for attempt in 0..2 {
        let result = execute_on_pool_once(state, &current_pool_key, sql, max_rows).await;
        let Some(error) = result.as_ref().err() else {
            return result;
        };

        match transfer_pool_error_action(safety, db_type, error) {
            PoolErrorAction::Keep => return result,
            PoolErrorAction::Discard => {
                state.remove_pool_by_key(&current_pool_key).await;
                return result;
            }
            PoolErrorAction::ReconnectAndRetry if attempt == 0 => {
                let Some(connection_id) = connection_id.as_deref() else {
                    state.remove_pool_by_key(&current_pool_key).await;
                    return result;
                };
                let catalog = catalog_from_pool_key(&current_pool_key).map(str::to_string);
                current_pool_key = state
                    .reconnect_pool_for_session_with_catalog(
                        connection_id,
                        database.as_deref(),
                        catalog.as_deref(),
                        client_session_id.as_deref(),
                    )
                    .await?;
            }
            PoolErrorAction::ReconnectAndRetry => {
                state.remove_pool_by_key(&current_pool_key).await;
                return result;
            }
        }
    }

    unreachable!("transfer pool execution retry loop runs at most twice")
}

async fn execute_on_pool_once(
    state: &AppState,
    pool_key: &str,
    sql: &str,
    max_rows: Option<usize>,
) -> Result<db::QueryResult, String> {
    // Read-only check: block transfer operations in readonly mode
    crate::query::check_read_only_for_connection(state, pool_key, sql).await?;
    let connections = state.connections.read().await;
    let pool = connections.get(pool_key).ok_or("Connection not found")?;

    match pool {
        PoolKind::Mysql(p, mode) => {
            let p = p.clone();
            let bare = *mode == crate::connection::MysqlMode::Bare;
            drop(connections);
            db::mysql::execute_query_with_max_rows(&p, sql, bare, max_rows, Default::default()).await
        }
        PoolKind::Postgres(p) => {
            let p = p.clone();
            drop(connections);
            db::postgres::execute_query_with_max_rows(&p, sql, max_rows).await
        }
        PoolKind::Sqlite(p) => {
            let p = p.clone();
            drop(connections);
            db::sqlite::execute_query_with_max_rows(&p, sql, max_rows).await
        }
        PoolKind::ClickHouse(client) => {
            let client = client.clone();
            let database = database_from_pool_key(pool_key).unwrap_or("default").to_string();
            drop(connections);
            db::clickhouse_driver::execute_query_with_max_rows(&client, &database, sql, max_rows).await
        }
        PoolKind::SqlServer(client) => {
            let client = client.clone();
            drop(connections);
            let mut client = client.lock().await;
            let result = db::sqlserver::execute_query_with_max_rows(&mut client, sql, max_rows).await;
            drop(client);
            result
        }
        PoolKind::Agent(client) => {
            let client = client.clone();
            let database = database_from_pool_key(pool_key).map(str::to_string);
            let sql = sql.to_string();
            drop(connections);
            let mut client = client.lock().await;
            let params = agent_execute_query_params(
                &sql,
                database.as_deref(),
                None,
                QueryExecutionOptions { max_rows, fetch_size: max_rows, ..QueryExecutionOptions::default() },
            );
            client.execute_query(params).await
        }
        #[cfg(feature = "duckdb-sidecar")]
        PoolKind::DuckDbWorker(client) => {
            let client = client.clone();
            let sql = sql.to_string();
            drop(connections);
            client.execute(None, sql, max_rows, None, None).await
        }
        _ => Err("Unsupported database type for transfer".to_string()),
    }
}

fn database_from_pool_key(pool_key: &str) -> Option<&str> {
    let base = pool_key.split_once(":session:").map(|(base, _)| base).unwrap_or(pool_key);
    let base = base.split_once(":catalog:").map(|(base, _)| base).unwrap_or(base);
    base.split_once(':').map(|(_, database)| database).filter(|database| !database.is_empty())
}

fn catalog_from_pool_key(pool_key: &str) -> Option<&str> {
    let base = pool_key.split_once(":session:").map(|(base, _)| base).unwrap_or(pool_key);
    base.split_once(":catalog:").map(|(_, catalog)| catalog).filter(|catalog| !catalog.is_empty())
}

pub async fn get_db_type(state: &AppState, connection_id: &str) -> Result<DatabaseType, String> {
    let configs = state.configs.read().await;
    configs.get(connection_id).map(|c| c.db_type).ok_or_else(|| format!("Connection config not found: {connection_id}"))
}

pub async fn get_columns_for_transfer(
    state: &AppState,
    pool_key: &str,
    _connection_id: &str,
    database: &str,
    schema: &str,
    table: &str,
    catalog: Option<&str>,
) -> Result<Vec<db::ColumnInfo>, String> {
    let connections = state.connections.read().await;

    #[cfg(feature = "duckdb-sidecar")]
    if let Some(PoolKind::DuckDbWorker(client)) = connections.get(pool_key) {
        let client = client.clone();
        let database = database.to_string();
        let schema = schema.to_string();
        let table = table.to_string();
        drop(connections);
        return client.list_columns(database, schema, table).await;
    }

    if let Some(PoolKind::ClickHouse(client)) = connections.get(pool_key) {
        let client = client.clone();
        let database = database.to_string();
        let table = table.to_string();
        drop(connections);
        return db::clickhouse_driver::get_columns(&client, &database, &table).await;
    }
    if let Some(PoolKind::SqlServer(client)) = connections.get(pool_key) {
        let client = client.clone();
        let schema = schema.to_string();
        let table = table.to_string();
        drop(connections);
        let mut client = client.lock().await;
        return db::sqlserver::get_columns(&mut client, &schema, &table).await;
    }
    if let Some(PoolKind::InfluxDb(client)) = connections.get(pool_key) {
        let client = client.clone();
        let database = database.to_string();
        let table = table.to_string();
        drop(connections);
        return db::influxdb_driver::get_columns(&client, &database, &table).await;
    }
    if let Some(PoolKind::Agent(client)) = connections.get(pool_key) {
        let client = client.clone();
        let database = database.to_string();
        let schema = schema.to_string();
        let table = table.to_string();
        drop(connections);
        let mut client = client.lock().await;
        return client.get_columns(&database, &schema, &table, None).await;
    }
    let pool = connections.get(pool_key).ok_or("Pool not found")?;
    let schema = schema.to_string();
    let table = table.to_string();
    match pool {
        PoolKind::Mysql(p, _) => {
            let p = p.clone();
            let catalog = normalize_external_catalog_name(catalog).map(str::to_string);
            drop(connections);
            if let Some(catalog) = catalog {
                // Use 3-part qualified column lookup for Doris/StarRocks external catalogs
                db::doris::get_catalog_columns(&p, &catalog, &schema, &table).await
            } else {
                db::mysql::get_columns(&p, &schema, &table).await
            }
        }
        PoolKind::Postgres(p) => {
            let p = p.clone();
            drop(connections);
            db::postgres::get_columns(&p, &schema, &table).await
        }
        PoolKind::Sqlite(p) => {
            let p = p.clone();
            drop(connections);
            db::sqlite::get_columns(&p, &schema, &table).await
        }
        _ => Err("Unsupported database type".to_string()),
    }
}

async fn get_postgres_indexes_for_transfer(
    state: &AppState,
    pool_key: &str,
    database: &str,
    schema: &str,
    table: &str,
) -> Result<Vec<db::IndexInfo>, String> {
    let connections = state.connections.read().await;
    if let Some(PoolKind::Agent(client)) = connections.get(pool_key) {
        let client = client.clone();
        let database = database.to_string();
        let schema = schema.to_string();
        let table = table.to_string();
        drop(connections);
        let mut client = client.lock().await;
        return client.list_indexes(&database, &schema, &table, None).await;
    }
    let Some(PoolKind::Postgres(pool)) = connections.get(pool_key) else {
        return Err("PostgreSQL pool not found".to_string());
    };
    let pool = pool.clone();
    drop(connections);
    db::postgres::list_indexes(&pool, schema, table).await
}

async fn get_postgres_foreign_keys_for_transfer(
    state: &AppState,
    pool_key: &str,
    database: &str,
    schema: &str,
    table: &str,
) -> Result<Vec<db::ForeignKeyInfo>, String> {
    let connections = state.connections.read().await;
    if let Some(PoolKind::Agent(client)) = connections.get(pool_key) {
        let client = client.clone();
        let database = database.to_string();
        let schema = schema.to_string();
        let table = table.to_string();
        drop(connections);
        let mut client = client.lock().await;
        return client.list_foreign_keys(&database, &schema, &table, None).await;
    }
    let Some(PoolKind::Postgres(pool)) = connections.get(pool_key) else {
        return Err("PostgreSQL pool not found".to_string());
    };
    let pool = pool.clone();
    drop(connections);
    db::postgres::list_foreign_keys(&pool, schema, table).await
}

async fn get_postgres_owned_sequences_for_transfer(
    state: &AppState,
    pool_key: &str,
    schema: &str,
    tables: &[String],
) -> Result<Vec<PostgresOwnedSequence>, String> {
    if tables.is_empty() {
        return Ok(Vec::new());
    }

    let pool = {
        let connections = state.connections.read().await;
        match connections.get(pool_key) {
            Some(PoolKind::Postgres(pool)) => pool.clone(),
            _ => return Ok(Vec::new()),
        }
    };
    let client = pool.get().await.map_err(|e| e.to_string())?;
    let rows = client
        .query(
            "SELECT c.relname, \
              t.relname, \
              a.attname \
             FROM pg_class c \
             JOIN pg_namespace n ON n.oid = c.relnamespace \
             LEFT JOIN pg_sequence s ON s.seqrelid = c.oid \
             JOIN pg_depend d ON d.classid = 'pg_class'::regclass \
               AND d.objid = c.oid \
               AND d.refclassid = 'pg_class'::regclass \
               AND d.deptype IN ('a', 'i') \
             JOIN pg_class t ON t.oid = d.refobjid \
             JOIN pg_namespace tn ON tn.oid = t.relnamespace AND tn.nspname = n.nspname \
             JOIN pg_attribute a ON a.attrelid = t.oid AND a.attnum = d.refobjsubid \
             WHERE c.relkind = 'S' AND n.nspname = $1 \
             ORDER BY t.relname, c.relname",
            &[&schema],
        )
        .await
        .map_err(|e| e.to_string())?;

    let selected: HashSet<&str> = tables.iter().map(String::as_str).collect();
    Ok(rows
        .iter()
        .filter_map(|row| {
            let owner_table = row.get::<_, String>(1);
            if !selected.contains(owner_table.as_str()) {
                return None;
            }
            Some(PostgresOwnedSequence {
                name: row.get::<_, String>(0),
                owner_table,
                owner_column: row.get::<_, String>(2),
            })
        })
        .collect())
}

async fn get_postgres_sequence_snapshots_for_transfer(
    state: &AppState,
    pool_key: &str,
    schema: &str,
) -> Result<Vec<PostgresSequenceSnapshot>, String> {
    let pool = {
        let connections = state.connections.read().await;
        match connections.get(pool_key) {
            Some(PoolKind::Postgres(pool)) => pool.clone(),
            _ => return Ok(Vec::new()),
        }
    };
    let client = pool.get().await.map_err(|e| e.to_string())?;
    let rows = client
        .query(
            "SELECT c.relname, \
              t.relname, \
              a.attname \
             FROM pg_class c \
             JOIN pg_namespace n ON n.oid = c.relnamespace \
             LEFT JOIN pg_sequence s ON s.seqrelid = c.oid \
             LEFT JOIN pg_depend d ON d.classid = 'pg_class'::regclass \
               AND d.objid = c.oid \
               AND d.refclassid = 'pg_class'::regclass \
               AND d.deptype IN ('a', 'i') \
             LEFT JOIN pg_class t ON t.oid = d.refobjid \
             LEFT JOIN pg_attribute a ON a.attrelid = t.oid AND a.attnum = d.refobjsubid \
             WHERE c.relkind = 'S' AND n.nspname = $1 \
             ORDER BY c.relname",
            &[&schema],
        )
        .await
        .map_err(|e| e.to_string())?;

    Ok(rows
        .iter()
        .map(|row| PostgresSequenceSnapshot {
            name: row.get::<_, String>(0),
            owner_table: row.get::<_, Option<String>>(1),
            owner_column: row.get::<_, Option<String>>(2),
        })
        .collect())
}

fn postgres_selected_sequences_sql(schema: &str, names: &[String]) -> Option<String> {
    if names.is_empty() {
        return None;
    }
    let name_list = names.iter().map(|name| quote_string_literal(name)).collect::<Vec<_>>().join(", ");
    Some(format!(
        "SELECT c.relname, \
          COALESCE(format_type(s.seqtypid, NULL), 'bigint'), \
          COALESCE(s.seqstart::text, '1'), \
          COALESCE(s.seqmin::text, '1'), \
          COALESCE(s.seqmax::text, '9223372036854775807'), \
          COALESCE(s.seqincrement::text, '1'), \
          CASE WHEN COALESCE(s.seqcycle, false) THEN 'true' ELSE 'false' END, \
          COALESCE(s.seqcache::text, '1'), \
          pg_sequence_last_value(c.oid)::text \
         FROM pg_catalog.pg_class c \
         JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace \
         LEFT JOIN pg_catalog.pg_sequence s ON s.seqrelid = c.oid \
         WHERE c.relkind = 'S' AND n.nspname = {} AND c.relname IN ({name_list}) \
         ORDER BY c.relname",
        quote_string_literal(schema)
    ))
}

async fn get_postgres_selected_sequences_for_transfer(
    state: &AppState,
    pool_key: &str,
    schema: &str,
    names: &[String],
) -> Result<Vec<PostgresTransferSequence>, String> {
    let Some(sql) = postgres_selected_sequences_sql(schema, names) else {
        return Ok(Vec::new());
    };
    Ok(execute_on_pool(state, pool_key, &sql)
        .await?
        .rows
        .into_iter()
        .filter_map(|row| {
            Some(PostgresTransferSequence {
                name: json_string_cell(&row, 0)?,
                data_type: json_string_cell(&row, 1)?,
                start_value: json_string_cell(&row, 2)?,
                min_value: json_string_cell(&row, 3)?,
                max_value: json_string_cell(&row, 4)?,
                increment: json_string_cell(&row, 5)?,
                cycle: json_string_cell(&row, 6).as_deref() == Some("true"),
                cache_value: json_string_cell(&row, 7)?,
                last_value: json_string_cell(&row, 8),
            })
        })
        .collect())
}

async fn get_existing_postgres_sequence_names_for_transfer(
    state: &AppState,
    pool_key: &str,
    schema: &str,
    names: &[String],
) -> Result<HashSet<String>, String> {
    if names.is_empty() {
        return Ok(HashSet::new());
    }
    let name_list = names.iter().map(|name| quote_string_literal(name)).collect::<Vec<_>>().join(", ");
    let sql = format!(
        "SELECT c.relname \
         FROM pg_catalog.pg_class c \
         JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace \
         WHERE c.relkind = 'S' AND n.nspname = {} AND c.relname IN ({name_list})",
        quote_string_literal(schema)
    );
    Ok(execute_on_pool(state, pool_key, &sql)
        .await?
        .rows
        .into_iter()
        .filter_map(|row| json_string_cell(&row, 0))
        .collect())
}

/// Create owned PostgreSQL sequences before executing reused table DDL because
/// serial defaults still reference `nextval('...')` in `CREATE TABLE`.
async fn prepare_postgres_owned_sequences_for_transfer(
    state: &AppState,
    request: &TransferRequest,
    table: &str,
    target_table: &str,
    source_pool_key: &str,
    target_pool_key: &str,
    pg_compat_transfer: bool,
    preserves_target_table_name: bool,
    target_table_preexisting: bool,
) -> Result<Vec<PostgresOwnedSequence>, String> {
    if !(request.create_table && pg_compat_transfer && preserves_target_table_name && !target_table_preexisting) {
        return Ok(Vec::new());
    }

    let owned_sequences =
        get_postgres_owned_sequences_for_transfer(state, source_pool_key, &request.source_schema, &[table.to_string()])
            .await?;
    if owned_sequences.is_empty() {
        return Ok(Vec::new());
    }

    let existing_sequences =
        get_postgres_sequence_snapshots_for_transfer(state, target_pool_key, &request.target_schema)
            .await?
            .into_iter()
            .map(|sequence| (sequence.name.clone(), sequence))
            .collect::<HashMap<_, _>>();

    for sequence in &owned_sequences {
        let should_create = validate_existing_postgres_sequence(
            sequence,
            existing_sequences.get(&sequence.name),
            &request.target_schema,
        )?;
        if should_create {
            let create_sql = format!(
                "CREATE SEQUENCE IF NOT EXISTS {}",
                postgres_sequence_qualified_name(&request.target_schema, &sequence.name)
            );
            execute_on_pool(state, target_pool_key, &create_sql)
                .await
                .map_err(|e| format!("Failed to create PostgreSQL sequence for {target_table}: {e}"))?;
        }
    }

    Ok(owned_sequences)
}

/// Bind created or reused sequences after the table exists so
/// `pg_get_serial_sequence(...)` can find them during later sequence sync.
async fn bind_postgres_owned_sequences_for_transfer(
    state: &AppState,
    request: &TransferRequest,
    target_table: &str,
    target_pool_key: &str,
    owned_sequences: &[PostgresOwnedSequence],
) -> Result<(), String> {
    for sequence in owned_sequences {
        let owner_sql = format!(
            "ALTER SEQUENCE {} OWNED BY {}.{}",
            postgres_sequence_qualified_name(&request.target_schema, &sequence.name),
            qualified_table(&sequence.owner_table, &request.target_schema, &DatabaseType::Postgres, None),
            quote_identifier(&sequence.owner_column, &DatabaseType::Postgres)
        );
        execute_on_pool(state, target_pool_key, &owner_sql)
            .await
            .map_err(|e| format!("Failed to bind PostgreSQL sequence for {target_table}: {e}"))?;
    }
    Ok(())
}

pub fn ordered_transfer_object_kinds(kinds: Vec<TransferObjectKind>) -> Vec<TransferObjectKind> {
    let rank = |kind: &TransferObjectKind| match kind {
        TransferObjectKind::Table => 0,
        TransferObjectKind::Sequence => 1,
        TransferObjectKind::View => 2,
        TransferObjectKind::MaterializedView => 2,
        TransferObjectKind::Function => 3,
        TransferObjectKind::Procedure => 4,
        TransferObjectKind::Trigger => 5,
        TransferObjectKind::Event => 6,
    };
    let mut kinds = kinds;
    kinds.sort_by_key(rank);
    kinds
}

#[derive(Debug, Clone, Default, Serialize)]
#[serde(rename_all = "camelCase")]
pub struct TransferObjectOutcome {
    pub transferred: Vec<String>,
    pub skipped: Vec<String>,
    pub failed: Vec<String>,
}

pub fn selected_object_names(selections: &[TransferObjectSelection], kind: &TransferObjectKind) -> Vec<String> {
    selections.iter().filter(|s| &s.object_type == kind).flat_map(|s| s.names.clone()).collect::<Vec<_>>()
}

fn selected_postgres_sequence_names(request: &TransferRequest) -> Vec<String> {
    let mut names = selected_object_names(&request.objects, &TransferObjectKind::Sequence);
    names.sort();
    names.dedup();
    names
}

fn postgres_transfer_relation_names(request: &TransferRequest) -> Vec<String> {
    let mut names = request.tables.clone();
    names.extend(selected_postgres_sequence_names(request));
    names.sort();
    names.dedup();
    names
}

/// Whether a kind participates in a transfer. An empty selection is the legacy
/// PG→PG default: every kind participates (views, functions, triggers,
/// materialized views are all transferred). Once the caller explicitly selects
/// objects, only kinds with a non-empty selection participate.
pub fn object_kind_selected_or_defaulted(selections: &[TransferObjectSelection], kind: &TransferObjectKind) -> bool {
    selections.is_empty() || !selected_object_names(selections, kind).is_empty()
}

pub fn should_copy_data(content: &TransferContent) -> bool {
    !matches!(content, TransferContent::StructureOnly)
}

fn transfer_kind_from_object_source_kind(kind: &db::ObjectSourceKind) -> Option<TransferObjectKind> {
    use db::ObjectSourceKind as S;
    Some(match kind {
        S::View => TransferObjectKind::View,
        S::MaterializedView => TransferObjectKind::MaterializedView,
        S::Procedure => TransferObjectKind::Procedure,
        S::Function => TransferObjectKind::Function,
        S::Trigger => TransferObjectKind::Trigger,
        S::Sequence => TransferObjectKind::Sequence,
        _ => return None,
    })
}

fn filter_object_sources_by_selection(
    sources: Vec<db::ObjectSource>,
    selections: &[TransferObjectSelection],
) -> Vec<db::ObjectSource> {
    // Empty selection is the legacy PG→PG default: transfer everything.
    if selections.is_empty() {
        return sources;
    }
    sources
        .into_iter()
        .filter(|source| {
            let Some(kind) = transfer_kind_from_object_source_kind(&source.object_type) else {
                return false;
            };
            selected_object_names(selections, &kind).contains(&source.name)
        })
        .collect()
}

/// Whether non-table schema-object transfer should run for a request.
/// Data-only transfers never include schema objects. In structure modes,
/// newer clients send an explicit `objects` selection; for those the answer
/// is simply whether any object was selected. PG→PG keeps the legacy default:
/// even an *empty* selection still transfers all views, functions, triggers,
/// policies, ownership and grants (the old table-selection flow always did).
pub fn should_transfer_schema_objects(
    source_db_type: &DatabaseType,
    target_db_type: &DatabaseType,
    content: &TransferContent,
    objects: &[TransferObjectSelection],
) -> bool {
    if matches!(content, TransferContent::DataOnly) {
        return false;
    }
    if !objects.is_empty() {
        return true;
    }
    transfer_object_family(source_db_type) == Some(TransferObjectFamily::Postgres)
        && transfer_object_family(target_db_type) == Some(TransferObjectFamily::Postgres)
}

/// Transfers selected non-table objects from source to target.
/// Skips objects that already exist on the target; counts them in the
/// outcome. Executes in dependency order (sequence → view → function →
/// procedure → trigger → event). Errors are collected per object and the
/// transfer continues.
pub async fn transfer_schema_objects<F>(
    state: &AppState,
    request: &TransferRequest,
    source_pool_key: &str,
    target_pool_key: &str,
    progress_callback: F,
) -> Result<TransferObjectOutcome, String>
where
    F: FnMut(TransferProgress),
{
    if matches!(request.content, TransferContent::DataOnly) {
        return Ok(TransferObjectOutcome::default());
    }
    let source_db_type = get_db_type(state, &request.source_connection_id).await?;
    let target_db_type = get_db_type(state, &request.target_connection_id).await?;
    if !should_transfer_schema_objects(&source_db_type, &target_db_type, &request.content, &request.objects) {
        return Ok(TransferObjectOutcome::default());
    }
    if !is_same_transfer_family(&source_db_type, &target_db_type) {
        return transfer_cross_family_schema_objects(
            state,
            request,
            source_pool_key,
            target_pool_key,
            progress_callback,
        )
        .await;
    }
    // Same-family path: drop selections whose object type is not transferable
    // for the source family (defense in depth — the UI already filters disabled
    // types at the request boundary, but requests can also arrive from older
    // clients or be crafted directly).
    let mut filtered_request = request.clone();
    if let Some(family) = transfer_object_family(&source_db_type) {
        let supported = transfer_object_kinds_for_family(&family);
        filtered_request.objects =
            request.objects.iter().filter(|sel| supported.contains(&sel.object_type)).cloned().collect();
    }
    match transfer_object_family(&source_db_type) {
        Some(TransferObjectFamily::Postgres) => {
            transfer_postgres_schema_objects(
                state,
                &filtered_request,
                source_pool_key,
                target_pool_key,
                progress_callback,
            )
            .await
        }
        Some(TransferObjectFamily::Mysql) => {
            transfer_mysql_schema_objects(state, &filtered_request, source_pool_key, target_pool_key, progress_callback)
                .await
        }
        Some(TransferObjectFamily::Oracle) => {
            transfer_oracle_schema_objects(
                state,
                &filtered_request,
                source_pool_key,
                target_pool_key,
                progress_callback,
            )
            .await
        }
        Some(TransferObjectFamily::SqlServer) => {
            transfer_sqlserver_schema_objects(
                state,
                &filtered_request,
                source_pool_key,
                target_pool_key,
                progress_callback,
            )
            .await
        }
        None => Ok(TransferObjectOutcome::default()),
    }
}

async fn transfer_mysql_schema_objects<F>(
    state: &AppState,
    request: &TransferRequest,
    source_pool_key: &str,
    target_pool_key: &str,
    mut progress_callback: F,
) -> Result<TransferObjectOutcome, String>
where
    F: FnMut(TransferProgress),
{
    let mut outcome = TransferObjectOutcome::default();
    let source_db = &request.source_database;
    let target_db =
        if request.target_database.trim().is_empty() { source_db.as_str() } else { request.target_database.as_str() };
    let order = ordered_transfer_object_kinds(request.objects.iter().map(|s| s.object_type).collect());
    for kind in order {
        for name in selected_object_names(&request.objects, &kind) {
            if is_cancelled(&request.transfer_id).await {
                return Err("Cancelled".to_string());
            }
            let table = format!("schema object: {name}");
            let mut progress = |outcome: &mut TransferObjectOutcome, status: TransferStatus, error: Option<String>| {
                progress_callback(TransferProgress {
                    transfer_id: request.transfer_id.clone(),
                    table: table.clone(),
                    table_index: request.tables.len(),
                    total_tables: request.tables.len(),
                    rows_transferred: (outcome.transferred.len() + outcome.skipped.len()) as u64,
                    total_rows: None,
                    status,
                    error,
                    terminal: false,
                });
            };
            // skip if the target already has it
            let exists_sql = target_object_exists_sql(&DatabaseType::Mysql, target_db, &name, &kind)?;
            let exists = !execute_on_pool(state, target_pool_key, &exists_sql).await?.rows.is_empty();
            if exists {
                outcome.skipped.push(format!("{kind:?}:{name}"));
                progress(&mut outcome, TransferStatus::Running, None);
                continue;
            }
            let query = mysql_object_source_query(&kind, source_db, &name)?;
            let result = execute_on_pool(state, source_pool_key, &query).await?;
            let raw_ddl = mysql_object_ddl_from_result(&kind, source_db, &result.rows)?;
            let ddl = strip_mysql_definer(&raw_ddl);
            let ddl = rewrite_mysql_schema_qualifier(&ddl, source_db, target_db);
            match execute_on_pool(state, target_pool_key, &ddl).await {
                Ok(_) => {
                    outcome.transferred.push(format!("{kind:?}:{name}"));
                    progress(&mut outcome, TransferStatus::Running, None);
                }
                Err(e) => {
                    outcome.failed.push(format!("{kind:?}:{name}"));
                    progress(&mut outcome, TransferStatus::Error, Some(e));
                }
            }
        }
    }
    Ok(outcome)
}

fn resolve_oracle_schema(schema: &str, database: &str) -> String {
    if schema.trim().is_empty() {
        database.to_string()
    } else {
        schema.to_string()
    }
}

async fn transfer_oracle_schema_objects<F>(
    state: &AppState,
    request: &TransferRequest,
    source_pool_key: &str,
    target_pool_key: &str,
    mut progress_callback: F,
) -> Result<TransferObjectOutcome, String>
where
    F: FnMut(TransferProgress),
{
    let mut outcome = TransferObjectOutcome::default();
    let source_schema = resolve_oracle_schema(&request.source_schema, &request.source_database);
    let target_schema = resolve_oracle_schema(&request.target_schema, &request.target_database);
    let order = ordered_transfer_object_kinds(request.objects.iter().map(|s| s.object_type).collect());
    for kind in order {
        for name in selected_object_names(&request.objects, &kind) {
            if is_cancelled(&request.transfer_id).await {
                return Err("Cancelled".to_string());
            }
            let table = format!("schema object: {name}");
            let mut progress = |outcome: &mut TransferObjectOutcome, status: TransferStatus, error: Option<String>| {
                progress_callback(TransferProgress {
                    transfer_id: request.transfer_id.clone(),
                    table: table.clone(),
                    table_index: request.tables.len(),
                    total_tables: request.tables.len(),
                    rows_transferred: (outcome.transferred.len() + outcome.skipped.len()) as u64,
                    total_rows: None,
                    status,
                    error,
                    terminal: false,
                });
            };
            // skip if the target already has it (ALL_OBJECTS works for both Oracle and Dameng)
            let exists_sql = target_object_exists_sql(&DatabaseType::Oracle, &target_schema, &name, &kind)?;
            let exists = !execute_on_pool(state, target_pool_key, &exists_sql).await?.rows.is_empty();
            if exists {
                outcome.skipped.push(format!("{kind:?}:{name}"));
                progress(&mut outcome, TransferStatus::Running, None);
                continue;
            }
            let query = oracle_object_source_query(&kind, &source_schema, &name)?;
            let result = execute_on_pool(state, source_pool_key, &query).await?;
            // DBMS_METADATA.GET_DDL resolves against the session's current
            // schema; if the pool session is not the owner schema the query
            // may return no row and the object is reported as failed (v1).
            let ddl = result
                .rows
                .first()
                .and_then(|row| row.first())
                .and_then(|value| value.as_str())
                .ok_or_else(|| format!("No DDL returned for Oracle {:?} {name}", kind))?
                .to_string();
            let ddl = rewrite_oracle_schema_qualifier(&ddl, &source_schema, &target_schema);
            match execute_on_pool(state, target_pool_key, &ddl).await {
                Ok(_) => {
                    outcome.transferred.push(format!("{kind:?}:{name}"));
                    progress(&mut outcome, TransferStatus::Running, None);
                }
                Err(e) => {
                    outcome.failed.push(format!("{kind:?}:{name}"));
                    progress(&mut outcome, TransferStatus::Error, Some(e));
                }
            }
        }
    }
    Ok(outcome)
}

async fn transfer_sqlserver_schema_objects<F>(
    state: &AppState,
    request: &TransferRequest,
    source_pool_key: &str,
    target_pool_key: &str,
    mut progress_callback: F,
) -> Result<TransferObjectOutcome, String>
where
    F: FnMut(TransferProgress),
{
    let mut outcome = TransferObjectOutcome::default();
    let source_schema =
        if request.source_schema.trim().is_empty() { "dbo".to_string() } else { request.source_schema.clone() };
    let target_schema =
        if request.target_schema.trim().is_empty() { "dbo".to_string() } else { request.target_schema.clone() };
    let order = ordered_transfer_object_kinds(request.objects.iter().map(|s| s.object_type).collect());
    for kind in order {
        for name in selected_object_names(&request.objects, &kind) {
            if is_cancelled(&request.transfer_id).await {
                return Err("Cancelled".to_string());
            }
            let table = format!("schema object: {name}");
            let mut progress = |outcome: &mut TransferObjectOutcome, status: TransferStatus, error: Option<String>| {
                progress_callback(TransferProgress {
                    transfer_id: request.transfer_id.clone(),
                    table: table.clone(),
                    table_index: request.tables.len(),
                    total_tables: request.tables.len(),
                    rows_transferred: (outcome.transferred.len() + outcome.skipped.len()) as u64,
                    total_rows: None,
                    status,
                    error,
                    terminal: false,
                });
            };
            let exists_sql = target_object_exists_sql(&DatabaseType::SqlServer, &target_schema, &name, &kind)?;
            let exists = !execute_on_pool(state, target_pool_key, &exists_sql).await?.rows.is_empty();
            if exists {
                outcome.skipped.push(format!("{kind:?}:{name}"));
                progress(&mut outcome, TransferStatus::Running, None);
                continue;
            }
            let query = sqlserver_object_source_query(&kind, &source_schema, &name)?;
            let result = execute_on_pool(state, source_pool_key, &query).await?;
            let ddl = match sqlserver_object_ddl_from_result(&result, &source_schema, &name, &kind) {
                Ok(ddl) => ddl,
                Err(e) => {
                    outcome.failed.push(format!("{kind:?}:{name}"));
                    progress(&mut outcome, TransferStatus::Error, Some(e));
                    continue;
                }
            };
            match execute_on_pool(state, target_pool_key, &ddl).await {
                Ok(_) => {
                    outcome.transferred.push(format!("{kind:?}:{name}"));
                    progress(&mut outcome, TransferStatus::Running, None);
                }
                Err(e) => {
                    outcome.failed.push(format!("{kind:?}:{name}"));
                    progress(&mut outcome, TransferStatus::Error, Some(e));
                }
            }
        }
    }
    Ok(outcome)
}

/// Transfers non-table objects across different database families.
/// Only mechanically rewriteable kinds (views, sequences) are allowed;
/// anything else is rejected up front with a descriptive error.
async fn transfer_cross_family_schema_objects<F>(
    state: &AppState,
    request: &TransferRequest,
    source_pool_key: &str,
    target_pool_key: &str,
    mut progress_callback: F,
) -> Result<TransferObjectOutcome, String>
where
    F: FnMut(TransferProgress),
{
    let mut outcome = TransferObjectOutcome::default();
    let source_db_type = get_db_type(state, &request.source_connection_id).await?;
    let target_db_type = get_db_type(state, &request.target_connection_id).await?;
    let allowed = cross_family_transferable_object_kinds(&source_db_type, &target_db_type);
    let unsupported: Vec<String> = request
        .objects
        .iter()
        .filter(|selection| !allowed.contains(&selection.object_type))
        .map(|selection| format!("{:?}", selection.object_type))
        .collect();
    if !unsupported.is_empty() {
        return Err(format!("跨库非表对象传输暂不支持该类型，不支持: {}", unsupported.join(", ")));
    }
    let source_family = transfer_object_family(&source_db_type).ok_or("unsupported source family")?;
    let target_family = transfer_object_family(&target_db_type).ok_or("unsupported target family")?;
    let resolve_schema = |schema: &str, database: &str, db_type: &DatabaseType| -> String {
        if !schema.trim().is_empty() {
            return schema.to_string();
        }
        match transfer_object_family(db_type) {
            Some(TransferObjectFamily::SqlServer) => "dbo".to_string(),
            _ => database.to_string(),
        }
    };
    let source_schema = resolve_schema(&request.source_schema, &request.source_database, &source_db_type);
    let target_schema = resolve_schema(&request.target_schema, &request.target_database, &target_db_type);
    let order = ordered_transfer_object_kinds(request.objects.iter().map(|s| s.object_type).collect());
    for kind in order {
        for name in selected_object_names(&request.objects, &kind) {
            if is_cancelled(&request.transfer_id).await {
                return Err("Cancelled".to_string());
            }
            let table = format!("schema object: {name}");
            let mut progress = |outcome: &mut TransferObjectOutcome, status: TransferStatus, error: Option<String>| {
                progress_callback(TransferProgress {
                    transfer_id: request.transfer_id.clone(),
                    table: table.clone(),
                    table_index: request.tables.len(),
                    total_tables: request.tables.len(),
                    rows_transferred: (outcome.transferred.len() + outcome.skipped.len()) as u64,
                    total_rows: None,
                    status,
                    error,
                    terminal: false,
                });
            };
            let exists_sql = target_object_exists_sql(&target_db_type, &target_schema, &name, &kind)?;
            let exists = !execute_on_pool(state, target_pool_key, &exists_sql).await?.rows.is_empty();
            if exists {
                outcome.skipped.push(format!("{kind:?}:{name}"));
                progress(&mut outcome, TransferStatus::Running, None);
                continue;
            }
            let query = match source_family {
                TransferObjectFamily::Mysql => mysql_object_source_query(&kind, &source_schema, &name)?,
                TransferObjectFamily::SqlServer => sqlserver_object_source_query(&kind, &source_schema, &name)?,
                TransferObjectFamily::Oracle => oracle_object_source_query(&kind, &source_schema, &name)?,
                TransferObjectFamily::Postgres => {
                    return Err(format!("跨库传输暂不支持 Postgres 源: {name}"));
                }
            };
            let result = execute_on_pool(state, source_pool_key, &query).await?;
            let raw_ddl = match source_family {
                TransferObjectFamily::Mysql => mysql_object_ddl_from_result(&kind, &source_schema, &result.rows)?,
                TransferObjectFamily::SqlServer => {
                    sqlserver_object_ddl_from_result(&result, &source_schema, &name, &kind)?
                }
                TransferObjectFamily::Oracle => result
                    .rows
                    .first()
                    .and_then(|row| row.first())
                    .and_then(|value| value.as_str())
                    .ok_or_else(|| format!("No DDL returned for Oracle {:?} {name}", kind))?
                    .to_string(),
                TransferObjectFamily::Postgres => {
                    return Err(format!("跨库传输暂不支持 Postgres 源: {name}"));
                }
            };
            let ddl = convert_cross_family_object_ddl(
                &source_family,
                &target_family,
                &kind,
                &source_schema,
                &target_schema,
                &raw_ddl,
            );
            match execute_on_pool(state, target_pool_key, &ddl).await {
                Ok(_) => {
                    outcome.transferred.push(format!("{kind:?}:{name}"));
                    progress(&mut outcome, TransferStatus::Running, None);
                }
                Err(e) => {
                    let e = if kind == TransferObjectKind::View
                        && (e.contains("无效的表或视图名") || e.contains("table or view does not exist"))
                    {
                        format!("{e}（视图引用的基表可能未在目标库中，请同时选择视图依赖的表或先传输这些表）")
                    } else {
                        e
                    };
                    outcome.failed.push(format!("{kind:?}:{name}"));
                    progress(&mut outcome, TransferStatus::Error, Some(e));
                }
            }
        }
    }
    Ok(outcome)
}
fn postgres_transfer_routine_catalog_capability_sql() -> &'static str {
    "SELECT EXISTS ( \
       SELECT 1 \
       FROM pg_catalog.pg_attribute \
       WHERE attrelid = 'pg_catalog.pg_proc'::regclass \
         AND attname = 'prokind' \
         AND NOT attisdropped \
     )"
}

async fn postgres_transfer_has_prokind(state: &AppState, pool_key: &str) -> Result<bool, String> {
    let result = execute_read_on_pool(state, pool_key, postgres_transfer_routine_catalog_capability_sql()).await?;
    result
        .rows
        .first()
        .and_then(|row| row.first())
        .and_then(|value| value.as_bool().or_else(|| value.as_str().and_then(|value| value.parse().ok())))
        .ok_or_else(|| "Failed to inspect PostgreSQL routine catalog capabilities".to_string())
}

fn postgres_transfer_routine_catalog_sql(has_prokind: bool) -> (&'static str, &'static str) {
    if has_prokind {
        ("CASE p.prokind WHEN 'p' THEN 'PROCEDURE' ELSE 'FUNCTION' END", "p.prokind IN ('p','f')")
    } else {
        ("'FUNCTION'", "NOT p.proisagg AND NOT p.proiswindow")
    }
}

fn postgres_transfer_routines_sql(schema: &str, has_prokind: bool) -> String {
    let (routine_kind, routine_filter) = postgres_transfer_routine_catalog_sql(has_prokind);
    format!(
        "SELECT p.proname, {routine_kind}, pg_get_functiondef(p.oid) \
         FROM pg_catalog.pg_proc p \
         JOIN pg_catalog.pg_namespace n ON n.oid = p.pronamespace \
         WHERE n.nspname = {schema} AND {routine_filter} \
         ORDER BY CASE WHEN {routine_kind} = 'PROCEDURE' THEN 0 ELSE 1 END, p.proname, p.oid",
        schema = quote_string_literal(schema),
    )
}

async fn get_postgres_schema_object_sources_for_transfer(
    state: &AppState,
    pool_key: &str,
    schema: &str,
    has_prokind: bool,
) -> Result<Vec<db::ObjectSource>, String> {
    let views_sql = format!(
        "SELECT c.relname, pg_get_viewdef(c.oid, true) \
         FROM pg_catalog.pg_class c \
         JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace \
         WHERE n.nspname = {} AND c.relkind = 'v' \
         ORDER BY c.relname",
        quote_string_literal(schema)
    );
    let routines_sql = postgres_transfer_routines_sql(schema, has_prokind);

    let mut sources = Vec::new();
    for row in execute_on_pool(state, pool_key, &views_sql).await?.rows {
        let Some(name) = json_string_cell(&row, 0) else {
            continue;
        };
        let Some(source) = json_string_cell(&row, 1) else {
            continue;
        };
        sources.push(db::ObjectSource {
            name,
            object_type: db::ObjectSourceKind::View,
            schema: Some(schema.to_string()),
            source,
            editable: None,
        });
    }
    for row in execute_on_pool(state, pool_key, &routines_sql).await?.rows {
        let Some(name) = json_string_cell(&row, 0) else {
            continue;
        };
        let kind = match json_string_cell(&row, 1).as_deref() {
            Some("PROCEDURE") => db::ObjectSourceKind::Procedure,
            _ => db::ObjectSourceKind::Function,
        };
        let Some(source) = json_string_cell(&row, 2) else {
            continue;
        };
        sources.push(db::ObjectSource {
            name,
            object_type: kind,
            schema: Some(schema.to_string()),
            source,
            editable: None,
        });
    }

    Ok(sources)
}

async fn get_postgres_materialized_view_sources_for_transfer(
    state: &AppState,
    pool_key: &str,
    schema: &str,
) -> Result<Vec<PostgresMaterializedViewSource>, String> {
    let sql = format!(
        "SELECT c.relname, pg_get_viewdef(c.oid, true) \
         FROM pg_catalog.pg_class c \
         JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace \
         WHERE n.nspname = {} AND c.relkind = 'm' \
         ORDER BY c.relname",
        quote_string_literal(schema)
    );
    let rows = execute_on_pool(state, pool_key, &sql).await?.rows;
    Ok(rows
        .into_iter()
        .filter_map(|row| {
            Some(PostgresMaterializedViewSource {
                view_name: json_string_cell(&row, 0)?,
                source: json_string_cell(&row, 1)?,
            })
        })
        .collect())
}

async fn get_postgres_trigger_sources_for_transfer(
    state: &AppState,
    pool_key: &str,
    schema: &str,
    tables: &[String],
) -> Result<Vec<PostgresTriggerSource>, String> {
    if tables.is_empty() {
        return Ok(Vec::new());
    }
    let table_list = tables.iter().map(|table| quote_string_literal(table)).collect::<Vec<_>>().join(", ");
    let sql = format!(
        "SELECT c.relname, t.tgname, pg_get_triggerdef(t.oid, true) \
         FROM pg_catalog.pg_trigger t \
         JOIN pg_catalog.pg_class c ON c.oid = t.tgrelid \
         JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace \
         WHERE n.nspname = {} AND NOT t.tgisinternal AND c.relname IN ({table_list}) \
         ORDER BY c.relname, t.tgname",
        quote_string_literal(schema)
    );
    let rows = execute_on_pool(state, pool_key, &sql).await?.rows;
    Ok(rows
        .into_iter()
        .filter_map(|row| {
            Some(PostgresTriggerSource {
                table_name: json_string_cell(&row, 0)?,
                trigger_name: json_string_cell(&row, 1)?,
                source: json_string_cell(&row, 2)?,
            })
        })
        .collect())
}

async fn get_postgres_extension_sources_for_transfer(
    state: &AppState,
    pool_key: &str,
    schema: &str,
) -> Result<Vec<PostgresExtensionSource>, String> {
    let sql = format!(
        "SELECT e.extname \
         FROM pg_extension e \
         JOIN pg_namespace n ON n.oid = e.extnamespace \
         WHERE n.nspname = {} \
         ORDER BY e.extname",
        quote_string_literal(schema)
    );
    let rows = execute_on_pool(state, pool_key, &sql).await?.rows;
    Ok(rows
        .into_iter()
        .filter_map(|row| json_string_cell(&row, 0).map(|extension_name| PostgresExtensionSource { extension_name }))
        .collect())
}

async fn get_postgres_enum_sources_for_transfer(
    state: &AppState,
    pool_key: &str,
    schema: &str,
) -> Result<Vec<PostgresEnumSource>, String> {
    let sql = format!(
        "SELECT t.typname, COALESCE(array_to_json(array_agg(e.enumlabel ORDER BY e.enumsortorder))::text, '[]') \
         FROM pg_type t \
         JOIN pg_namespace n ON n.oid = t.typnamespace \
         LEFT JOIN pg_enum e ON e.enumtypid = t.oid \
         WHERE n.nspname = {} AND t.typtype = 'e' \
         GROUP BY t.typname \
         ORDER BY t.typname",
        quote_string_literal(schema)
    );
    let rows = execute_on_pool(state, pool_key, &sql).await?.rows;
    Ok(rows
        .into_iter()
        .filter_map(|row| {
            let type_name = json_string_cell(&row, 0)?;
            let labels_json = json_string_cell(&row, 1)?;
            let labels = serde_json::from_str::<Vec<String>>(&labels_json).ok()?;
            Some(PostgresEnumSource { type_name, labels })
        })
        .collect())
}

async fn get_postgres_domain_sources_for_transfer(
    state: &AppState,
    pool_key: &str,
    schema: &str,
) -> Result<Vec<PostgresDomainSource>, String> {
    let sql = format!(
        "SELECT t.typname, \
                pg_catalog.format_type(t.typbasetype, t.typtypmod), \
                NULLIF(t.typdefault, ''), \
                t.typnotnull, \
                COALESCE(( \
                    SELECT array_to_json(array_agg(pg_get_constraintdef(c.oid, true) ORDER BY c.conname))::text \
                    FROM pg_constraint c \
                    WHERE c.contypid = t.oid AND c.contype = 'c' \
                ), '[]') \
         FROM pg_type t \
         JOIN pg_namespace n ON n.oid = t.typnamespace \
         WHERE n.nspname = {} AND t.typtype = 'd' \
         ORDER BY t.typname",
        quote_string_literal(schema)
    );
    let rows = execute_on_pool(state, pool_key, &sql).await?.rows;
    Ok(rows
        .into_iter()
        .filter_map(|row| {
            let domain_name = json_string_cell(&row, 0)?;
            let base_type = json_string_cell(&row, 1)?;
            let default_value = json_string_cell(&row, 2);
            let not_null = row.get(3).and_then(|value| value.as_bool()).unwrap_or(false);
            let checks = json_string_cell(&row, 4)
                .and_then(|json| serde_json::from_str::<Vec<String>>(&json).ok())
                .unwrap_or_default();
            Some(PostgresDomainSource { domain_name, base_type, default_value, not_null, checks })
        })
        .collect())
}

async fn get_postgres_policy_statements_for_transfer(
    state: &AppState,
    pool_key: &str,
    source_schema: &str,
    target_schema: &str,
    tables: &[String],
) -> Result<Vec<String>, String> {
    if tables.is_empty() {
        return Ok(Vec::new());
    }
    let table_list = tables.iter().map(|table| quote_string_literal(table)).collect::<Vec<_>>().join(", ");
    let sql = format!(
        "WITH selected_tables AS ( \
             SELECT c.oid, c.relname, c.relrowsecurity, c.relforcerowsecurity \
             FROM pg_catalog.pg_class c \
             JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace \
             WHERE n.nspname = {source_schema} AND c.relkind IN ('r','p') AND c.relname IN ({table_list}) \
         ), \
         policy_rows AS ( \
             SELECT t.relname, t.relrowsecurity, t.relforcerowsecurity, p.polname, p.polpermissive, p.polcmd, \
                    COALESCE((SELECT string_agg(CASE WHEN role_oid = 0 THEN 'PUBLIC' ELSE quote_ident(r.rolname) END, ', ' ORDER BY CASE WHEN role_oid = 0 THEN '' ELSE r.rolname END) \
                              FROM unnest(p.polroles) AS role_oid LEFT JOIN pg_roles r ON r.oid = role_oid), '') AS role_list, \
                    pg_get_expr(p.polqual, p.polrelid) AS using_expr, \
                    pg_get_expr(p.polwithcheck, p.polrelid) AS with_check_expr \
             FROM selected_tables t \
             JOIN pg_catalog.pg_policy p ON p.polrelid = t.oid \
         ) \
         SELECT stmt FROM ( \
             SELECT format('ALTER TABLE %I.%I ENABLE ROW LEVEL SECURITY', {target_schema}, relname) AS stmt, relname, 0 AS sort_order \
             FROM selected_tables WHERE relrowsecurity \
             UNION ALL \
             SELECT format('ALTER TABLE %I.%I FORCE ROW LEVEL SECURITY', {target_schema}, relname) AS stmt, relname, 1 AS sort_order \
             FROM selected_tables WHERE relforcerowsecurity \
             UNION ALL \
             SELECT format('DROP POLICY IF EXISTS %I ON %I.%I', polname, {target_schema}, relname) AS stmt, relname, 2 AS sort_order \
             FROM policy_rows \
             UNION ALL \
             SELECT format( \
                 'CREATE POLICY %I ON %I.%I AS %s FOR %s%s%s%s', \
                 polname, {target_schema}, relname, \
                 CASE WHEN polpermissive THEN 'PERMISSIVE' ELSE 'RESTRICTIVE' END, \
                 CASE polcmd WHEN 'r' THEN 'SELECT' WHEN 'a' THEN 'INSERT' WHEN 'w' THEN 'UPDATE' WHEN 'd' THEN 'DELETE' ELSE 'ALL' END, \
                 CASE WHEN role_list <> '' THEN ' TO ' || role_list ELSE '' END, \
                 CASE WHEN using_expr IS NOT NULL THEN ' USING (' || using_expr || ')' ELSE '' END, \
                 CASE WHEN with_check_expr IS NOT NULL THEN ' WITH CHECK (' || with_check_expr || ')' ELSE '' END \
             ) AS stmt, relname, 3 AS sort_order \
             FROM policy_rows \
         ) statements \
         ORDER BY relname, sort_order, stmt",
        source_schema = quote_string_literal(source_schema),
        target_schema = quote_string_literal(target_schema),
    );
    Ok(result_rows_to_string_statements(execute_on_pool(state, pool_key, &sql).await?.rows))
}

fn postgres_transfer_ownership_statements_sql(
    source_schema: &str,
    target_schema: &str,
    tables: &[String],
    has_prokind: bool,
) -> String {
    let table_list = tables.iter().map(|table| quote_string_literal(table)).collect::<Vec<_>>().join(", ");
    let table_filter = if tables.is_empty() { "FALSE".to_string() } else { format!("c.relname IN ({table_list})") };
    let (routine_kind, routine_filter) = postgres_transfer_routine_catalog_sql(has_prokind);
    format!(
        "WITH relation_owners AS ( \
             SELECT CASE c.relkind \
                      WHEN 'm' THEN format('ALTER MATERIALIZED VIEW %I.%I OWNER TO ', {target_schema}, c.relname) \
                      WHEN 'v' THEN format('ALTER VIEW %I.%I OWNER TO ', {target_schema}, c.relname) \
                      WHEN 'f' THEN format('ALTER FOREIGN TABLE %I.%I OWNER TO ', {target_schema}, c.relname) \
                      WHEN 'S' THEN format('ALTER SEQUENCE %I.%I OWNER TO ', {target_schema}, c.relname) \
                      ELSE format('ALTER TABLE %I.%I OWNER TO ', {target_schema}, c.relname) \
                    END AS stmt_prefix, \
                    pg_get_userbyid(c.relowner) AS owner_name \
             FROM pg_catalog.pg_class c \
             JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace \
             WHERE n.nspname = {source_schema} AND (c.relkind IN ('v','m') OR ({table_filter} AND c.relkind IN ('r','p','f','S'))) \
         ), \
         routine_owners AS ( \
             SELECT format('ALTER %s %I.%I(%s) OWNER TO ', \
                           {routine_kind}, {target_schema}, p.proname, pg_get_function_identity_arguments(p.oid)) AS stmt_prefix, \
                    pg_get_userbyid(p.proowner) AS owner_name \
             FROM pg_catalog.pg_proc p \
             JOIN pg_catalog.pg_namespace n ON n.oid = p.pronamespace \
             WHERE n.nspname = {source_schema} AND {routine_filter} \
         ), \
         type_owners AS ( \
             SELECT format('ALTER %s %I.%I OWNER TO ', \
                           CASE t.typtype WHEN 'd' THEN 'DOMAIN' ELSE 'TYPE' END, \
                           {target_schema}, t.typname) AS stmt_prefix, \
                    pg_get_userbyid(t.typowner) AS owner_name \
             FROM pg_catalog.pg_type t \
             JOIN pg_catalog.pg_namespace n ON n.oid = t.typnamespace \
             WHERE n.nspname = {source_schema} AND t.typtype IN ('e','d') \
         ) \
         SELECT stmt_prefix, owner_name FROM ( \
             SELECT format('ALTER SCHEMA %I OWNER TO ', {target_schema}) AS stmt_prefix, \
                    pg_get_userbyid(n.nspowner) AS owner_name \
             FROM pg_catalog.pg_namespace n WHERE n.nspname = {source_schema} \
             UNION ALL SELECT stmt_prefix, owner_name FROM relation_owners \
             UNION ALL SELECT stmt_prefix, owner_name FROM routine_owners \
             UNION ALL SELECT stmt_prefix, owner_name FROM type_owners \
         ) statements \
         WHERE stmt_prefix IS NOT NULL AND owner_name IS NOT NULL",
        source_schema = quote_string_literal(source_schema),
        target_schema = quote_string_literal(target_schema),
        table_filter = table_filter,
    )
}

async fn get_postgres_ownership_statements_for_transfer(
    state: &AppState,
    pool_key: &str,
    source_schema: &str,
    target_schema: &str,
    tables: &[String],
    has_prokind: bool,
) -> Result<Vec<PostgresOwnershipStatement>, String> {
    let sql = postgres_transfer_ownership_statements_sql(source_schema, target_schema, tables, has_prokind);
    Ok(result_rows_to_postgres_ownership_statements(execute_on_pool(state, pool_key, &sql).await?.rows))
}

fn distinct_postgres_ownership_roles(statements: &[PostgresOwnershipStatement]) -> Vec<String> {
    let mut roles = statements.iter().map(|statement| statement.owner.clone()).collect::<Vec<_>>();
    roles.sort();
    roles.dedup();
    roles
}

async fn get_postgres_current_user(state: &AppState, target_pool_key: &str) -> Result<String, String> {
    let rows = execute_on_pool(state, target_pool_key, "SELECT current_user").await?.rows;
    rows.first()
        .and_then(|row| json_string_cell(row, 0))
        .filter(|user| !user.trim().is_empty())
        .ok_or_else(|| "Failed to read target PostgreSQL current user".to_string())
}

async fn get_existing_postgres_roles(
    state: &AppState,
    target_pool_key: &str,
    roles: &[String],
) -> Result<HashSet<String>, String> {
    if roles.is_empty() {
        return Ok(HashSet::new());
    }
    let role_list = roles.iter().map(|role| quote_string_literal(role)).collect::<Vec<_>>().join(", ");
    let sql = format!("SELECT rolname FROM pg_catalog.pg_roles WHERE rolname IN ({role_list})");
    let rows = execute_on_pool(state, target_pool_key, &sql).await?.rows;
    Ok(rows.into_iter().filter_map(|row| json_string_cell(&row, 0)).collect())
}

fn build_postgres_ownership_statement(statement: &PostgresOwnershipStatement, owner: &str) -> String {
    format!("{}{}", statement.sql_prefix, quote_identifier(owner, &DatabaseType::Postgres))
}

pub async fn preview_transfer_ownership(
    state: &AppState,
    request: &TransferRequest,
    source_db_type: &DatabaseType,
    target_db_type: &DatabaseType,
    source_pool_key: &str,
    target_pool_key: &str,
) -> Result<TransferOwnershipPreview, String> {
    if !request.create_table || !is_postgres_compat_transfer(source_db_type, target_db_type) {
        return Ok(TransferOwnershipPreview { missing_owners: Vec::new(), target_owner: String::new() });
    }

    let has_prokind = postgres_transfer_has_prokind(state, source_pool_key).await?;
    let relation_names = postgres_transfer_relation_names(request);
    let statements = get_postgres_ownership_statements_for_transfer(
        state,
        source_pool_key,
        &request.source_schema,
        &request.target_schema,
        &relation_names,
        has_prokind,
    )
    .await?;
    let roles = distinct_postgres_ownership_roles(&statements);
    let existing_roles = get_existing_postgres_roles(state, target_pool_key, &roles).await?;
    let missing_owners = roles.into_iter().filter(|role| !existing_roles.contains(role)).collect::<Vec<_>>();
    let target_owner = if missing_owners.is_empty() {
        String::new()
    } else {
        get_postgres_current_user(state, target_pool_key).await?
    };

    Ok(TransferOwnershipPreview { missing_owners, target_owner })
}

fn postgres_transfer_grant_statements_sql(
    source_schema: &str,
    target_schema: &str,
    tables: &[String],
    has_prokind: bool,
) -> String {
    let table_list = tables.iter().map(|table| quote_string_literal(table)).collect::<Vec<_>>().join(", ");
    let table_filter = if tables.is_empty() { "FALSE".to_string() } else { format!("c.relname IN ({table_list})") };
    let (routine_kind, routine_filter) = postgres_transfer_routine_catalog_sql(has_prokind);
    format!(
        "WITH schema_grants AS ( \
             SELECT format( \
                 'GRANT %s ON SCHEMA %I TO %s%s', \
                 string_agg(a.privilege_type, ', ' ORDER BY a.privilege_type), \
                 {target_schema}, \
                 CASE WHEN a.grantee = 0 THEN 'PUBLIC' ELSE quote_ident(grantee.rolname) END, \
                 CASE WHEN bool_or(a.is_grantable) THEN ' WITH GRANT OPTION' ELSE '' END \
             ) AS stmt \
             FROM pg_catalog.pg_namespace n \
             JOIN LATERAL aclexplode(n.nspacl) a ON true \
             LEFT JOIN pg_roles grantee ON grantee.oid = a.grantee \
             WHERE n.nspname = {source_schema} \
             GROUP BY a.grantee, grantee.rolname \
         ), \
         relation_grants AS ( \
             SELECT format( \
                 'GRANT %s ON %s %I.%I TO %s%s', \
                 string_agg(privilege_type, ', ' ORDER BY privilege_type), \
                 CASE WHEN relkind = 'S' THEN 'SEQUENCE' ELSE 'TABLE' END, \
                 {target_schema}, relname, \
                 CASE WHEN grantee = 0 THEN 'PUBLIC' ELSE quote_ident(rolname) END, \
                 CASE WHEN bool_or(is_grantable) THEN ' WITH GRANT OPTION' ELSE '' END \
             ) AS stmt \
             FROM ( \
                 SELECT c.relname, c.relkind, a.grantee, a.privilege_type, a.is_grantable, grantee.rolname \
                 FROM pg_catalog.pg_class c \
                 JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace \
                 JOIN LATERAL aclexplode(c.relacl) a ON true \
                 LEFT JOIN pg_roles grantee ON grantee.oid = a.grantee \
                 WHERE n.nspname = {source_schema} AND (c.relkind IN ('v','m') OR ({table_filter} AND c.relkind IN ('r','p','f','S'))) \
             ) rels \
             GROUP BY relname, relkind, grantee, rolname \
         ), \
         routine_grants AS ( \
             SELECT format( \
                 'GRANT %s ON %s %I.%I(%s) TO %s%s', \
                 string_agg(privilege_type, ', ' ORDER BY privilege_type), \
                 routine_kind, \
                 {target_schema}, proname, identity_args, \
                 CASE WHEN grantee = 0 THEN 'PUBLIC' ELSE quote_ident(rolname) END, \
                 CASE WHEN bool_or(is_grantable) THEN ' WITH GRANT OPTION' ELSE '' END \
             ) AS stmt \
             FROM ( \
                 SELECT p.proname, {routine_kind} AS routine_kind, \
                        pg_get_function_identity_arguments(p.oid) AS identity_args, a.grantee, a.privilege_type, \
                        a.is_grantable, grantee.rolname \
                 FROM pg_catalog.pg_proc p \
                 JOIN pg_catalog.pg_namespace n ON n.oid = p.pronamespace \
                 JOIN LATERAL aclexplode(p.proacl) a ON true \
                 LEFT JOIN pg_roles grantee ON grantee.oid = a.grantee \
                 WHERE n.nspname = {source_schema} AND {routine_filter} \
             ) routines \
             GROUP BY proname, routine_kind, identity_args, grantee, rolname \
         ) \
         SELECT stmt FROM ( \
             SELECT stmt FROM schema_grants \
             UNION ALL SELECT stmt FROM relation_grants \
             UNION ALL SELECT stmt FROM routine_grants \
         ) statements \
         WHERE stmt IS NOT NULL",
        source_schema = quote_string_literal(source_schema),
        target_schema = quote_string_literal(target_schema),
        table_filter = table_filter,
    )
}

async fn get_postgres_grant_statements_for_transfer(
    state: &AppState,
    pool_key: &str,
    source_schema: &str,
    target_schema: &str,
    tables: &[String],
    has_prokind: bool,
) -> Result<Vec<String>, String> {
    let sql = postgres_transfer_grant_statements_sql(source_schema, target_schema, tables, has_prokind);
    Ok(result_rows_to_string_statements(execute_on_pool(state, pool_key, &sql).await?.rows))
}

pub async fn is_cancelled(transfer_id: &str) -> bool {
    CANCELLED.read().await.contains(transfer_id)
}

pub async fn set_cancelled(transfer_id: &str) {
    CANCELLED.write().await.insert(transfer_id.to_string());
}

pub async fn clear_cancelled(transfer_id: &str) {
    CANCELLED.write().await.remove(transfer_id);
}

/// Sort table names by foreign key dependency.
///
/// When `parents_first` is true (data transfer / SQL export), referenced (parent)
/// tables come before referencing (child) tables so inserts don't violate FK
/// constraints.
///
/// When `parents_first` is false (batch drop), referencing (child) tables come
/// first so they are dropped before the tables they reference.
///
/// Uses Kahn's algorithm for topological sort; tables involved in cycles keep
/// their original relative order after all cycle-free tables.
pub async fn sort_tables_by_fk_dependency(
    state: &AppState,
    connection_id: &str,
    database: &str,
    schema: &str,
    tables: &[String],
    parents_first: bool,
) -> Result<Vec<String>, String> {
    if tables.len() <= 1 {
        return Ok(tables.to_vec());
    }

    let db_type = state
        .configs
        .read()
        .await
        .get(connection_id)
        .map(|config| config.db_type)
        .ok_or_else(|| format!("Connection config not found: {connection_id}"))?;
    let postgres_pool = if db_type == DatabaseType::Postgres {
        let pool_key = state.get_or_create_pool(connection_id, Some(database)).await?;
        {
            let connections = state.connections.read().await;
            native_postgres_dependency_pool(connections.get(&pool_key))
        }
    } else {
        None
    };
    let dependencies = if let Some(pool) = postgres_pool {
        db::postgres::list_table_dependencies(&pool, schema).await?
    } else {
        let mut dependencies = Vec::new();
        for table in tables {
            let fks = crate::schema::list_foreign_keys_core(state, connection_id, database, schema, table).await?;
            dependencies.extend(fks.into_iter().map(|fk| (table.clone(), fk.ref_table)));
        }
        dependencies
    };

    Ok(sort_table_names_by_dependencies(tables, &dependencies, parents_first))
}

fn native_postgres_dependency_pool(pool_kind: Option<&PoolKind>) -> Option<deadpool_postgres::Pool> {
    match pool_kind {
        Some(PoolKind::Postgres(pool)) => Some(pool.clone()),
        _ => None,
    }
}

pub(crate) fn sort_table_names_by_dependencies(
    tables: &[String],
    dependencies: &[(String, String)],
    parents_first: bool,
) -> Vec<String> {
    let table_set: HashSet<&str> = tables.iter().map(|table| table.as_str()).collect();

    // Build in-degree and dependents graph.
    // parents_first=true:  edge ref_table → table     (parent before child)
    // parents_first=false: edge table → ref_table      (child before parent)
    let mut in_degree: HashMap<&str, usize> = HashMap::new();
    let mut dependents: HashMap<&str, Vec<&str>> = HashMap::new();

    for table in tables {
        in_degree.entry(table.as_str()).or_insert(0);
    }
    let mut seen_dependencies = HashSet::new();
    for (table, ref_table) in dependencies {
        if !table_set.contains(table.as_str()) || !table_set.contains(ref_table.as_str()) {
            continue;
        }
        if !seen_dependencies.insert((table.as_str(), ref_table.as_str())) {
            continue;
        }
        if parents_first {
            // FK-bearing table depends on ref_table — parent comes first.
            *in_degree.entry(table.as_str()).or_insert(0) += 1;
            dependents.entry(ref_table.as_str()).or_default().push(table.as_str());
        } else {
            // ref_table depends on FK-bearing table — child comes first.
            *in_degree.entry(ref_table.as_str()).or_insert(0) += 1;
            dependents.entry(table.as_str()).or_default().push(ref_table.as_str());
        }
    }

    // Kahn's algorithm.
    let mut queue: std::collections::VecDeque<&str> = tables
        .iter()
        .map(String::as_str)
        .filter(|table| in_degree.get(table).copied().unwrap_or_default() == 0)
        .collect();

    let mut sorted: Vec<String> = Vec::new();
    while let Some(table) = queue.pop_front() {
        sorted.push(table.to_string());
        if let Some(deps) = dependents.get(table) {
            for &dependent in deps {
                let deg = in_degree.get_mut(dependent).unwrap();
                *deg -= 1;
                if *deg == 0 {
                    queue.push_back(dependent);
                }
            }
        }
    }

    // Append any tables left behind by cycles in their original order.
    if sorted.len() < tables.len() {
        let sorted_set: HashSet<&str> = sorted.iter().map(|s| s.as_str()).collect();
        let mut remaining: Vec<String> = Vec::new();
        for table in tables {
            if !sorted_set.contains(table.as_str()) {
                remaining.push(table.clone());
            }
        }
        sorted.extend(remaining);
    }

    sorted
}

#[allow(clippy::too_many_arguments)]
async fn transfer_mongodb_table<F>(
    state: &AppState,
    request: &TransferRequest,
    table: &str,
    table_index: usize,
    source_db_type: &DatabaseType,
    target_db_type: &DatabaseType,
    source_pool_key: &str,
    target_pool_key: &str,
    mut progress_callback: F,
) -> Result<u64, String>
where
    F: FnMut(TransferProgress),
{
    let total_tables = request.tables.len();
    let ResolvedTransferTargetTable { name: target_table, preexisting: target_table_preexisting } =
        resolve_transfer_target_table_name(
            state,
            request,
            table,
            target_pool_key,
            target_db_type,
            request.source_catalog.as_deref(),
            request.target_catalog.as_deref(),
        )
        .await;
    let batch_size = if request.batch_size == 0 { 1000 } else { request.batch_size };
    let mut offset: u64 = 0;
    let mut total_transferred: u64 = 0;
    let mut total_rows = None;

    if request.mode == TransferMode::Upsert {
        log::warn!("[transfer] MongoDB upsert is not supported yet, falling back to append");
    }

    if is_mongodb_transfer_type(target_db_type) && request.mode == TransferMode::Overwrite {
        overwrite_mongo_collection_for_transfer(
            state,
            &request.target_connection_id,
            &request.target_database,
            &target_table,
        )
        .await
        .map_err(|e| format!("Failed to clear MongoDB collection '{target_table}': {e}"))?;
    }

    let mut sql_target_column_names: Vec<String> = Vec::new();
    let mut sql_target_column_types: Vec<Option<String>> = Vec::new();
    let mut sql_target_prepared = false;

    loop {
        if is_cancelled(&request.transfer_id).await {
            return Err("Cancelled".to_string());
        }

        let documents = if is_mongodb_transfer_type(source_db_type) {
            let result = if is_mongodb_transfer_type(target_db_type) {
                find_mongo_documents_extended_json(
                    state,
                    &request.source_connection_id,
                    &request.source_database,
                    table,
                    offset,
                    batch_size,
                )
                .await?
            } else {
                find_mongo_documents_for_rows(
                    state,
                    &request.source_connection_id,
                    &request.source_database,
                    table,
                    offset,
                    batch_size,
                )
                .await?
            };
            total_rows = Some(result.total);
            result.documents
        } else {
            let columns = get_columns_for_transfer(
                state,
                source_pool_key,
                &request.source_connection_id,
                &request.source_database,
                &request.source_schema,
                table,
                request.source_catalog.as_deref(),
            )
            .await?;
            let col_names = columns.iter().map(|column| column.name.clone()).collect::<Vec<_>>();
            let primary_key_columns = transfer_key_columns(&columns, source_db_type);
            let sql = pagination_sql_with_order(
                &col_names,
                table,
                &request.source_schema,
                source_db_type,
                offset,
                batch_size,
                &primary_key_columns,
                request.source_catalog.as_deref(),
            );
            let result = execute_on_pool(state, source_pool_key, &sql).await?;
            sql_rows_to_mongo_documents(&col_names, &result.rows)
        };

        let row_count = documents.len();
        if row_count == 0 {
            break;
        }

        if is_mongodb_transfer_type(target_db_type) {
            if is_mongodb_transfer_type(source_db_type) {
                insert_mongo_documents_extended_json_for_transfer(
                    state,
                    &request.target_connection_id,
                    &request.target_database,
                    &target_table,
                    &documents,
                )
                .await
            } else {
                insert_mongo_documents_for_transfer(
                    state,
                    &request.target_connection_id,
                    &request.target_database,
                    &target_table,
                    &documents,
                )
                .await
            }
            .map_err(|e| format!("Insert failed for MongoDB collection '{target_table}' at offset {offset}: {e}"))?;
        } else {
            if !sql_target_prepared {
                let mut sql_target_columns = mongo_columns_from_documents(&documents);
                if sql_target_columns.is_empty() {
                    sql_target_columns.push(db::ColumnInfo {
                        name: "document".to_string(),
                        data_type: "json".to_string(),
                        is_nullable: true,
                        column_default: None,
                        is_primary_key: false,
                        extra: None,
                        comment: None,
                        numeric_precision: None,
                        numeric_scale: None,
                        character_maximum_length: None,
                        enum_values: None,
                        ..Default::default()
                    });
                }
                sql_target_column_names = sql_target_columns.iter().map(|column| column.name.clone()).collect();
                sql_target_column_types =
                    sql_target_columns.iter().map(|column| Some(column.data_type.clone())).collect();

                if request.create_table {
                    if !target_table_preexisting {
                        let ddl = generate_create_table_ddl(
                            &sql_target_columns,
                            &target_table,
                            &request.source_schema,
                            &request.target_schema,
                            target_db_type,
                            source_db_type,
                            None,
                            request.target_catalog.as_deref(),
                        );
                        let target_table_created = transfer_create_table_created(
                            execute_on_pool(state, target_pool_key, &ddl).await.map(|_| ()),
                            &format!("Failed to create table from MongoDB collection '{table}'"),
                        )?;
                        if target_table_created {
                            for stmt in generate_comment_ddl(
                                &sql_target_columns,
                                &target_table,
                                &request.target_schema,
                                target_db_type,
                                None,
                            ) {
                                if let Err(e) = execute_on_pool(state, target_pool_key, &stmt).await {
                                    log::warn!(
                                        "[transfer] failed to set MongoDB transfer column comment for {}: {}",
                                        target_table,
                                        e
                                    );
                                }
                            }
                        }
                    } else {
                        log::info!(
                            "[transfer] target table {} already exists, skipping create-table DDL",
                            target_table
                        );
                    }
                }

                if request.mode == TransferMode::Overwrite {
                    let full_table = qualified_table(
                        &target_table,
                        &request.target_schema,
                        target_db_type,
                        request.target_catalog.as_deref(),
                    );
                    let truncate_sql = match target_db_type {
                        DatabaseType::Sqlite | DatabaseType::CloudflareD1 | DatabaseType::DuckDb => {
                            format!("DELETE FROM {full_table}")
                        }
                        _ => format!("TRUNCATE TABLE {full_table}"),
                    };
                    execute_on_pool(state, target_pool_key, &truncate_sql)
                        .await
                        .map_err(|e| format!("Failed to truncate MongoDB transfer target table: {e}"))?;
                }

                sql_target_prepared = true;
            }

            let rows = if sql_target_column_names.len() == 1 && sql_target_column_names[0] == "document" {
                documents.iter().map(|document| vec![document.clone()]).collect::<Vec<_>>()
            } else {
                mongo_documents_to_rows(&documents, &sql_target_column_names)
            };
            let write_statements = generate_transfer_write_sql_batches(
                &TransferMode::Append,
                &sql_target_column_names,
                &sql_target_column_types,
                &rows,
                &target_table,
                &request.target_schema,
                target_db_type,
                &[],
                request.target_catalog.as_deref(),
                false,
                false,
            )?;
            for (statement_index, batch_sql) in write_statements.iter().enumerate() {
                execute_on_pool(state, target_pool_key, batch_sql).await.map_err(|e| {
                    format!(
                        "Insert failed for MongoDB collection '{target_table}' at offset {offset}, chunk {} of {}: {e}",
                        statement_index + 1,
                        write_statements.len()
                    )
                })?;
            }
        }

        total_transferred += row_count as u64;
        offset += row_count as u64;

        progress_callback(TransferProgress {
            transfer_id: request.transfer_id.clone(),
            table: table.to_string(),
            table_index,
            total_tables,
            rows_transferred: total_transferred,
            total_rows,
            status: TransferStatus::Running,
            error: None,
            terminal: false,
        });

        if row_count < batch_size {
            break;
        }
    }

    Ok(total_transferred)
}

/// Transfer a single table. Returns rows transferred.
/// `progress_callback` is invoked for progress updates.
#[allow(clippy::too_many_arguments)]
pub async fn transfer_table<F>(
    state: &AppState,
    request: &TransferRequest,
    table: &str,
    table_index: usize,
    source_db_type: &DatabaseType,
    target_db_type: &DatabaseType,
    source_pool_key: &str,
    target_pool_key: &str,
    mut progress_callback: F,
) -> Result<u64, String>
where
    F: FnMut(TransferProgress),
{
    if is_mongodb_transfer_type(source_db_type) || is_mongodb_transfer_type(target_db_type) {
        return transfer_mongodb_table(
            state,
            request,
            table,
            table_index,
            source_db_type,
            target_db_type,
            source_pool_key,
            target_pool_key,
            progress_callback,
        )
        .await;
    }

    let total_tables = request.tables.len();
    let pg_compat_transfer = is_postgres_compat_transfer(source_db_type, target_db_type);
    let ResolvedTransferTargetTable { name: target_table, preexisting: mut target_table_preexisting } =
        resolve_transfer_target_table_name(
            state,
            request,
            table,
            target_pool_key,
            target_db_type,
            request.source_catalog.as_deref(),
            request.target_catalog.as_deref(),
        )
        .await;
    let preserves_target_table_name = target_table == table;

    // Get source columns (deduplicate by name)
    let columns = {
        let raw = get_columns_for_transfer(
            state,
            source_pool_key,
            &request.source_connection_id,
            &request.source_database,
            &request.source_schema,
            table,
            request.source_catalog.as_deref(),
        )
        .await?;
        let mut seen = std::collections::HashSet::new();
        raw.into_iter().filter(|c| seen.insert(c.name.clone())).collect::<Vec<_>>()
    };

    if columns.is_empty() {
        return Err(format!("No columns found for table {table}"));
    }

    let writable_columns = writable_transfer_columns(&columns, source_db_type, target_db_type);
    if writable_columns.is_empty() {
        return Err(format!("No writable columns found for table {table}"));
    }

    let col_names: Vec<String> = writable_columns.iter().map(|c| c.name.clone()).collect();
    let col_types: Vec<Option<String>> = writable_columns.iter().map(|c| Some(c.data_type.clone())).collect();
    let primary_key_columns = transfer_key_columns(&writable_columns, source_db_type);
    log::info!("[transfer] {} has {} columns, counting rows...", table, columns.len());

    // Fetch source table comment
    // Route through the catalog-aware path for Doris/StarRocks external catalogs
    // so the comment comes from the selected catalog, not the default one.
    let table_comment: Option<String> =
        if let Some(catalog) = resolve_external_transfer_catalog(request.source_catalog.as_deref(), source_db_type) {
            crate::schema::list_doris_catalog_tables_core(
                state,
                &request.source_connection_id,
                catalog,
                &request.source_database,
                Some(table),
                Some(1),
                None,
                None,
                None,
            )
            .await
            .unwrap_or_default()
            .into_iter()
            .next()
            .and_then(|t| t.comment)
        } else {
            crate::schema::list_tables_core(
                state,
                &request.source_connection_id,
                &request.source_database,
                &request.source_schema,
                Some(table),
                Some(1),
                None,
                None,
                None,
            )
            .await
            .unwrap_or_default()
            .into_iter()
            .next()
            .and_then(|t| t.comment)
        };

    let source_indexes =
        if request.create_table && pg_compat_transfer && preserves_target_table_name && !target_table_preexisting {
            get_postgres_indexes_for_transfer(
                state,
                source_pool_key,
                &request.source_database,
                &request.source_schema,
                table,
            )
            .await?
        } else {
            Vec::new()
        };
    let source_foreign_keys =
        if request.create_table && pg_compat_transfer && preserves_target_table_name && !target_table_preexisting {
            get_postgres_foreign_keys_for_transfer(
                state,
                source_pool_key,
                &request.source_database,
                &request.source_schema,
                table,
            )
            .await?
        } else {
            Vec::new()
        };

    // Count source rows
    let total_rows = {
        let sql = count_sql(table, &request.source_schema, source_db_type, request.source_catalog.as_deref());
        match execute_on_pool(state, source_pool_key, &sql).await {
            Ok(result) => result.rows.first().and_then(|r| r.first()).and_then(|v| match v {
                serde_json::Value::Number(n) => n.as_u64(),
                serde_json::Value::String(s) => s.parse::<u64>().ok(),
                _ => None,
            }),
            Err(e) => {
                log::warn!("[transfer] count failed for {}: {}", table, e);
                None
            }
        }
    };
    log::info!("[transfer] {} total_rows={:?}", table, total_rows);

    // Create table on target if requested
    if request.create_table {
        if is_postgres_transfer_dialect(target_db_type) && !request.target_schema.trim().is_empty() {
            let create_schema_sql =
                format!("CREATE SCHEMA IF NOT EXISTS {}", quote_identifier(&request.target_schema, target_db_type));
            execute_on_pool(state, target_pool_key, &create_schema_sql)
                .await
                .map_err(|e| format!("Failed to ensure schema exists: {e}"))?;
        }
        if target_table_preexisting {
            log::info!("[transfer] target table {} already exists, skipping create-table DDL", target_table);
        } else {
            let owned_sequences = prepare_postgres_owned_sequences_for_transfer(
                state,
                request,
                table,
                &target_table,
                source_pool_key,
                target_pool_key,
                pg_compat_transfer,
                preserves_target_table_name,
                target_table_preexisting,
            )
            .await?;
            let (source_driver_profile, target_driver_profile) = {
                let configs = state.configs.read().await;
                (
                    configs.get(&request.source_connection_id).and_then(|config| config.driver_profile.clone()),
                    configs.get(&request.target_connection_id).and_then(|config| config.driver_profile.clone()),
                )
            };
            let can_reuse_source_ddl = can_reuse_source_table_ddl(
                source_db_type,
                target_db_type,
                source_driver_profile.as_deref(),
                target_driver_profile.as_deref(),
                preserves_target_table_name,
            );
            let mut reused_source_ddl = false;
            let ddl = if can_reuse_source_ddl {
                let (source_ddl, source_ddl_was_read) = if let Some(catalog) =
                    resolve_external_transfer_catalog(request.source_catalog.as_deref(), source_db_type)
                {
                    // Doris/StarRocks external catalog: read DDL directly via
                    // SHOW CREATE TABLE catalog.database.table using the
                    // existing source pool (bare MySQL — addresses any catalog).
                    let pool = {
                        let connections = state.connections.read().await;
                        let pool =
                            connections.get(source_pool_key).ok_or_else(|| "Source pool not found".to_string())?;
                        let PoolKind::Mysql(p, _) = pool else {
                            return Err("Source pool must be MySQL-family for catalog DDL".to_string());
                        };
                        p.clone()
                    };
                    match db::doris::get_catalog_table_ddl(&pool, catalog, &request.source_database, table).await {
                        Ok(ddl) => (ddl, true),
                        Err(err) => {
                            log::warn!("[transfer] catalog DDL read failed for {table} in catalog '{catalog}': {err}; falling back to generated DDL");
                            (
                                generate_create_table_ddl(
                                    &columns,
                                    &target_table,
                                    &request.source_schema,
                                    &request.target_schema,
                                    target_db_type,
                                    source_db_type,
                                    table_comment.as_deref(),
                                    request.target_catalog.as_deref(),
                                ),
                                false,
                            )
                        }
                    }
                } else {
                    match crate::schema::get_table_ddl_core(
                        state,
                        &request.source_connection_id,
                        &request.source_database,
                        &request.source_schema,
                        table,
                        None,
                    )
                    .await
                    {
                        Ok(ddl) => (ddl, true),
                        Err(_) => (
                            generate_create_table_ddl(
                                &columns,
                                &target_table,
                                &request.source_schema,
                                &request.target_schema,
                                target_db_type,
                                source_db_type,
                                table_comment.as_deref(),
                                request.target_catalog.as_deref(),
                            ),
                            false,
                        ),
                    }
                };
                if contains_oceanbase_mysql_table_options(&source_ddl)
                    && !is_oceanbase_mysql_profile(target_db_type, target_driver_profile.as_deref())
                {
                    generate_create_table_ddl(
                        &columns,
                        &target_table,
                        &request.source_schema,
                        &request.target_schema,
                        target_db_type,
                        source_db_type,
                        table_comment.as_deref(),
                        request.target_catalog.as_deref(),
                    )
                } else {
                    reused_source_ddl = source_ddl_was_read;
                    rewrite_transfer_source_table_ddl(
                        &source_ddl,
                        &request.source_schema,
                        &request.target_schema,
                        source_db_type,
                        target_db_type,
                    )
                }
            } else {
                generate_create_table_ddl(
                    &columns,
                    &target_table,
                    &request.source_schema,
                    &request.target_schema,
                    target_db_type,
                    source_db_type,
                    table_comment.as_deref(),
                    request.target_catalog.as_deref(),
                )
            };
            log::info!("[transfer] creating target table: {}", ddl.chars().take(200).collect::<String>());
            let target_table_created = transfer_create_table_created(
                execute_transfer_create_table_ddl_on_pool(
                    state,
                    target_pool_key,
                    &ddl,
                    target_db_type,
                    reused_source_ddl,
                )
                .await,
                "Failed to create table",
            )?;
            if target_table_created {
                let comment_stmts = generate_comment_ddl(
                    &columns,
                    &target_table,
                    &request.target_schema,
                    target_db_type,
                    table_comment.as_deref(),
                );
                for stmt in &comment_stmts {
                    if let Err(e) = execute_on_pool(state, target_pool_key, stmt).await {
                        log::warn!("[transfer] failed to set column comment for {}: {}", target_table, e);
                    }
                }
                bind_postgres_owned_sequences_for_transfer(
                    state,
                    request,
                    &target_table,
                    target_pool_key,
                    &owned_sequences,
                )
                .await?;
            } else {
                // DDL may report the table already exists even when metadata
                // lookup missed it (case/schema differences or localized errors).
                target_table_preexisting = true;
            }
        }
    }

    // Structure-only transfer: DDL work (create table, indexes, comments) is
    // done above; skip everything data-related.
    if !should_copy_data(&request.content) {
        return Ok(0);
    }

    // Truncate target if overwrite mode
    if request.mode == TransferMode::Overwrite {
        let full_table =
            qualified_table(&target_table, &request.target_schema, target_db_type, request.target_catalog.as_deref());
        let truncate_sql = match target_db_type {
            DatabaseType::Sqlite | DatabaseType::CloudflareD1 | DatabaseType::DuckDb => {
                format!("DELETE FROM {full_table}")
            }
            _ => format!("TRUNCATE TABLE {full_table}"),
        };
        execute_on_pool(state, target_pool_key, &truncate_sql).await.map_err(|e| format!("Failed to truncate: {e}"))?;
    }

    let target_columns = if (request.mode == TransferMode::Upsert
        && !matches!(target_db_type, DatabaseType::ClickHouse | DatabaseType::Hive))
        || matches!(target_db_type, DatabaseType::Postgres | DatabaseType::Dameng)
    {
        get_columns_for_transfer(
            state,
            target_pool_key,
            &request.target_connection_id,
            &request.target_database,
            &request.target_schema,
            &target_table,
            request.target_catalog.as_deref(),
        )
        .await
        .unwrap_or_default()
    } else {
        Vec::new()
    };

    // Determine effective mode and PK columns for upsert
    let (effective_mode, pk_columns) = if request.mode == TransferMode::Upsert {
        if matches!(target_db_type, DatabaseType::ClickHouse | DatabaseType::Hive) {
            log::warn!("[transfer] upsert not supported for {:?}, falling back to append", target_db_type);
            (TransferMode::Append, vec![])
        } else {
            let pks: Vec<String> = transfer_key_columns(&target_columns, target_db_type)
                .into_iter()
                .filter(|name| col_names.iter().any(|column_name| column_name.eq_ignore_ascii_case(name)))
                .collect();
            if pks.is_empty() {
                log::warn!("[transfer] table {} has no primary key, falling back to append", table);
                (TransferMode::Append, vec![])
            } else {
                (TransferMode::Upsert, pks)
            }
        }
    } else {
        (request.mode.clone(), vec![])
    };

    let writes_dameng_identity_columns = matches!(target_db_type, DatabaseType::Dameng)
        && selected_columns_include_identity_columns(&col_names, &target_columns);
    let overrides_postgres_system_values = matches!(target_db_type, DatabaseType::Postgres)
        && selected_columns_include_postgres_generated_always_identity_columns(&col_names, &target_columns);
    // Transfer data in batches
    let batch_size = if request.batch_size == 0 { 1000 } else { request.batch_size };
    let mut offset: u64 = 0;
    let mut total_transferred: u64 = 0;

    loop {
        if is_cancelled(&request.transfer_id).await {
            return Err("Cancelled".to_string());
        }

        let sql = pagination_sql_with_order(
            &col_names,
            table,
            &request.source_schema,
            source_db_type,
            offset,
            batch_size,
            &primary_key_columns,
            request.source_catalog.as_deref(),
        );
        let (sql, mysql_spatial_markers) =
            mysql_spatial_transfer_select_sql(sql, &col_names, &col_types, source_db_type, target_db_type);
        let result = execute_on_pool(state, source_pool_key, &sql).await?;
        let row_count = result.rows.len();

        if row_count == 0 {
            break;
        }

        let write_statements = generate_transfer_write_sql_batches(
            &effective_mode,
            &col_names,
            &col_types,
            &result.rows,
            &target_table,
            &request.target_schema,
            target_db_type,
            &pk_columns,
            request.target_catalog.as_deref(),
            overrides_postgres_system_values,
            mysql_spatial_markers,
        )?;
        for (statement_index, batch_sql) in write_statements.iter().enumerate() {
            execute_transfer_write_statement(
                state,
                target_pool_key,
                batch_sql,
                target_db_type,
                &target_table,
                &request.target_schema,
                writes_dameng_identity_columns,
            )
            .await
            .map_err(|e| {
                let absolute_row = parse_mysql_row_error(&e).map(|row| offset + row);
                match absolute_row {
                    Some(row) => format!(
                        "Insert failed for table '{target_table}' at row {row} (chunk {} of {}): {e}",
                        statement_index + 1,
                        write_statements.len()
                    ),
                    None => format!(
                        "Insert failed for table '{target_table}' at offset {offset}, chunk {} of {}: {e}",
                        statement_index + 1,
                        write_statements.len()
                    ),
                }
            })?;
        }

        total_transferred += row_count as u64;
        log::info!("[transfer] {} batch +{} rows (total {})", table, row_count, total_transferred);
        offset += row_count as u64;

        progress_callback(TransferProgress {
            transfer_id: request.transfer_id.clone(),
            table: table.to_string(),
            table_index,
            total_tables,
            rows_transferred: total_transferred,
            total_rows,
            status: TransferStatus::Running,
            error: None,
            terminal: false,
        });

        if row_count < batch_size {
            break;
        }
    }

    if pg_compat_transfer {
        for statement in generate_postgres_sequence_sync_sql(&columns, &target_table, &request.target_schema) {
            execute_on_pool(state, target_pool_key, &statement)
                .await
                .map_err(|e| format!("Failed to sync PostgreSQL sequence for {target_table}: {e}"))?;
        }
    }

    if request.create_table && pg_compat_transfer && preserves_target_table_name && !target_table_preexisting {
        for statement in generate_postgres_index_ddl(&source_indexes, &target_table, &request.target_schema) {
            execute_on_pool(state, target_pool_key, &statement)
                .await
                .map_err(|e| format!("Failed to create PostgreSQL index for {target_table}: {e}"))?;
        }
        for statement in generate_postgres_foreign_key_ddl(
            &source_foreign_keys,
            &target_table,
            &request.source_schema,
            &request.target_schema,
        ) {
            execute_on_pool(state, target_pool_key, &statement)
                .await
                .map_err(|e| format!("Failed to create PostgreSQL foreign key for {target_table}: {e}"))?;
        }
    }

    Ok(total_transferred)
}

pub async fn transfer_postgres_schema_dependencies<F>(
    state: &AppState,
    request: &TransferRequest,
    source_pool_key: &str,
    target_pool_key: &str,
    mut progress_callback: F,
) -> Result<(), String>
where
    F: FnMut(TransferProgress),
{
    let source_db_type = get_db_type(state, &request.source_connection_id).await?;
    let target_db_type = get_db_type(state, &request.target_connection_id).await?;
    if !request.create_table || !is_postgres_compat_transfer(&source_db_type, &target_db_type) {
        return Ok(());
    }

    if !request.target_schema.trim().is_empty() {
        let schema_exists =
            execute_on_pool(state, target_pool_key, &postgres_schema_exists_sql(&request.target_schema))
                .await
                .map_err(|e| format!("Failed to check PostgreSQL target schema: {e}"))?;
        if !query_result_has_rows(&schema_exists) {
            // CREATE SCHEMA requires database-level CREATE privilege even with
            // IF NOT EXISTS, so only issue it after confirming the schema is absent.
            let create_schema_sql =
                format!("CREATE SCHEMA {}", quote_identifier(&request.target_schema, &DatabaseType::Postgres));
            execute_on_pool(state, target_pool_key, &create_schema_sql)
                .await
                .map_err(|e| format!("Failed to create PostgreSQL target schema: {e}"))?;
        }
    }

    let extensions =
        get_postgres_extension_sources_for_transfer(state, source_pool_key, &request.source_schema).await?;
    let enum_types = get_postgres_enum_sources_for_transfer(state, source_pool_key, &request.source_schema).await?;
    let domains = get_postgres_domain_sources_for_transfer(state, source_pool_key, &request.source_schema).await?;
    let selected_sequence_names = selected_postgres_sequence_names(request);
    let selected_sequences = get_postgres_selected_sequences_for_transfer(
        state,
        source_pool_key,
        &request.source_schema,
        &selected_sequence_names,
    )
    .await?;
    let existing_sequence_names = get_existing_postgres_sequence_names_for_transfer(
        state,
        target_pool_key,
        &request.target_schema,
        &selected_sequence_names,
    )
    .await?;
    let selected_sequences = selected_sequences
        .into_iter()
        .filter(|sequence| !existing_sequence_names.contains(&sequence.name))
        .collect::<Vec<_>>();
    let total_steps = extensions.len() + enum_types.len() + domains.len() + selected_sequences.len();
    let table_index = 0;
    let mut completed_steps = 0_u64;

    for extension in extensions {
        if is_cancelled(&request.transfer_id).await {
            return Err("Cancelled".to_string());
        }
        completed_steps += 1;
        progress_callback(TransferProgress {
            transfer_id: request.transfer_id.clone(),
            table: format!("extension: {}", extension.extension_name),
            table_index,
            total_tables: request.tables.len(),
            rows_transferred: completed_steps,
            total_rows: Some(total_steps as u64),
            status: TransferStatus::Running,
            error: None,
            terminal: false,
        });
        execute_on_pool(state, target_pool_key, &generate_postgres_extension_ddl(&extension, &request.target_schema))
            .await
            .map_err(|e| format!("Failed to create PostgreSQL extension {}: {e}", extension.extension_name))?;
    }

    for enum_type in enum_types {
        if is_cancelled(&request.transfer_id).await {
            return Err("Cancelled".to_string());
        }
        completed_steps += 1;
        progress_callback(TransferProgress {
            transfer_id: request.transfer_id.clone(),
            table: format!("enum: {}", enum_type.type_name),
            table_index,
            total_tables: request.tables.len(),
            rows_transferred: completed_steps,
            total_rows: Some(total_steps as u64),
            status: TransferStatus::Running,
            error: None,
            terminal: false,
        });
        execute_on_pool(state, target_pool_key, &generate_postgres_enum_ddl(&enum_type, &request.target_schema))
            .await
            .map_err(|e| format!("Failed to create PostgreSQL enum {}: {e}", enum_type.type_name))?;
    }

    for domain in domains {
        if is_cancelled(&request.transfer_id).await {
            return Err("Cancelled".to_string());
        }
        completed_steps += 1;
        progress_callback(TransferProgress {
            transfer_id: request.transfer_id.clone(),
            table: format!("domain: {}", domain.domain_name),
            table_index,
            total_tables: request.tables.len(),
            rows_transferred: completed_steps,
            total_rows: Some(total_steps as u64),
            status: TransferStatus::Running,
            error: None,
            terminal: false,
        });
        execute_on_pool(state, target_pool_key, &generate_postgres_domain_ddl(&domain, &request.target_schema))
            .await
            .map_err(|e| format!("Failed to create PostgreSQL domain {}: {e}", domain.domain_name))?;
    }

    for sequence in selected_sequences {
        if is_cancelled(&request.transfer_id).await {
            return Err("Cancelled".to_string());
        }
        completed_steps += 1;
        progress_callback(TransferProgress {
            transfer_id: request.transfer_id.clone(),
            table: format!("sequence: {}", sequence.name),
            table_index,
            total_tables: request.tables.len(),
            rows_transferred: completed_steps,
            total_rows: Some(total_steps as u64),
            status: TransferStatus::Running,
            error: None,
            terminal: false,
        });
        execute_on_pool(
            state,
            target_pool_key,
            &generate_postgres_transfer_sequence_create_ddl(&sequence, &request.target_schema),
        )
        .await
        .map_err(|e| format!("Failed to create PostgreSQL sequence {}: {e}", sequence.name))?;
        if let Some(setval_sql) = generate_postgres_transfer_sequence_setval_sql(&sequence, &request.target_schema) {
            execute_on_pool(state, target_pool_key, &setval_sql)
                .await
                .map_err(|e| format!("Failed to restore PostgreSQL sequence {} value: {e}", sequence.name))?;
        }
    }

    Ok(())
}

pub async fn transfer_postgres_schema_objects<F>(
    state: &AppState,
    request: &TransferRequest,
    source_pool_key: &str,
    target_pool_key: &str,
    mut progress_callback: F,
) -> Result<TransferObjectOutcome, String>
where
    F: FnMut(TransferProgress),
{
    let source_db_type = get_db_type(state, &request.source_connection_id).await?;
    let target_db_type = get_db_type(state, &request.target_connection_id).await?;
    if !request.create_table || !is_postgres_compat_transfer(&source_db_type, &target_db_type) {
        return Ok(TransferObjectOutcome::default());
    }

    let has_prokind = postgres_transfer_has_prokind(state, source_pool_key).await?;
    let mut outcome = TransferObjectOutcome::default();
    let object_sources = filter_object_sources_by_selection(
        get_postgres_schema_object_sources_for_transfer(state, source_pool_key, &request.source_schema, has_prokind)
            .await?,
        &request.objects,
    );
    let materialized_views =
        get_postgres_materialized_view_sources_for_transfer(state, source_pool_key, &request.source_schema)
            .await?
            .into_iter()
            .filter(|view| {
                object_kind_selected_or_defaulted(&request.objects, &TransferObjectKind::MaterializedView)
                    && selected_object_names(&request.objects, &TransferObjectKind::MaterializedView)
                        .contains(&view.view_name)
            })
            .collect::<Vec<_>>();
    let trigger_sources =
        get_postgres_trigger_sources_for_transfer(state, source_pool_key, &request.source_schema, &request.tables)
            .await?
            .into_iter()
            .filter(|trigger| {
                object_kind_selected_or_defaulted(&request.objects, &TransferObjectKind::Trigger)
                    && selected_object_names(&request.objects, &TransferObjectKind::Trigger)
                        .contains(&trigger.trigger_name)
            })
            .collect::<Vec<_>>();
    let policy_statements = get_postgres_policy_statements_for_transfer(
        state,
        source_pool_key,
        &request.source_schema,
        &request.target_schema,
        &request.tables,
    )
    .await?;
    let relation_names = postgres_transfer_relation_names(request);
    let ownership_statements = if matches!(request.ownership_policy, TransferOwnershipPolicy::Skip) {
        Vec::new()
    } else {
        get_postgres_ownership_statements_for_transfer(
            state,
            source_pool_key,
            &request.source_schema,
            &request.target_schema,
            &relation_names,
            has_prokind,
        )
        .await?
    };
    let ownership_existing_roles = if matches!(request.ownership_policy, TransferOwnershipPolicy::ReassignMissing) {
        let roles = distinct_postgres_ownership_roles(&ownership_statements);
        get_existing_postgres_roles(state, target_pool_key, &roles).await?
    } else {
        HashSet::new()
    };
    let ownership_target_user = if matches!(request.ownership_policy, TransferOwnershipPolicy::ReassignMissing)
        && !ownership_statements.is_empty()
    {
        Some(get_postgres_current_user(state, target_pool_key).await?)
    } else {
        None
    };
    let grant_statements = get_postgres_grant_statements_for_transfer(
        state,
        source_pool_key,
        &request.source_schema,
        &request.target_schema,
        &relation_names,
        has_prokind,
    )
    .await?;
    let materialized_view_step_count = materialized_views
        .iter()
        .map(|view| generate_postgres_materialized_view_ddls(view, &request.target_schema).len())
        .sum::<usize>();
    let trigger_step_count = trigger_sources.len() * 2;
    let total_steps = object_sources.len()
        + materialized_view_step_count
        + trigger_step_count
        + policy_statements.len()
        + ownership_statements.len()
        + grant_statements.len();
    let table_index = request.tables.len();
    let mut completed_steps = 0_u64;

    for object in object_sources {
        if is_cancelled(&request.transfer_id).await {
            return Err("Cancelled".to_string());
        }
        let Some(object_kind) = transfer_kind_from_object_source_kind(&object.object_type) else {
            continue;
        };
        let exists_sql =
            target_object_exists_sql(&DatabaseType::Postgres, &request.target_schema, &object.name, &object_kind)?;
        let exists = !execute_on_pool(state, target_pool_key, &exists_sql).await?.rows.is_empty();
        if exists {
            outcome.skipped.push(format!("{object_kind:?}:{}", object.name));
            continue;
        }
        completed_steps += 1;
        progress_callback(TransferProgress {
            transfer_id: request.transfer_id.clone(),
            table: format!("schema object: {}", object.name),
            table_index,
            total_tables: request.tables.len(),
            rows_transferred: completed_steps,
            total_rows: Some(total_steps as u64),
            status: TransferStatus::Running,
            error: None,
            terminal: false,
        });

        let rewritten_source = match object.object_type {
            db::ObjectSourceKind::View | db::ObjectSourceKind::MaterializedView => object.source.clone(),
            db::ObjectSourceKind::Procedure | db::ObjectSourceKind::Function => {
                rewrite_postgres_routine_schema(&object.source, &request.source_schema, &request.target_schema)
                    .unwrap_or_else(|| object.source.clone())
            }
            db::ObjectSourceKind::Sequence
            | db::ObjectSourceKind::Synonym
            | db::ObjectSourceKind::Package
            | db::ObjectSourceKind::PackageBody => object.source.clone(),
            db::ObjectSourceKind::Trigger | db::ObjectSourceKind::Type | db::ObjectSourceKind::TypeBody => {
                object.source.clone()
            }
        };
        let statements = build_executable_object_source_statements(EditableObjectSourceSqlInput {
            database_type: DatabaseType::Postgres,
            object_type: object.object_type.clone(),
            schema: Some(request.target_schema.clone()),
            name: object.name.clone(),
            source: rewritten_source,
        })?;
        for statement in statements {
            execute_on_pool(state, target_pool_key, &statement)
                .await
                .map_err(|e| format!("Failed to create PostgreSQL {:?} {}: {e}", object.object_type, object.name))?;
        }
        outcome.transferred.push(format!("{object_kind:?}:{}", object.name));
    }

    for view in materialized_views {
        let exists_sql = target_object_exists_sql(
            &DatabaseType::Postgres,
            &request.target_schema,
            &view.view_name,
            &TransferObjectKind::MaterializedView,
        )?;
        let exists = !execute_on_pool(state, target_pool_key, &exists_sql).await?.rows.is_empty();
        if exists {
            outcome.skipped.push(format!("MaterializedView:{}", view.view_name));
            continue;
        }
        for statement in generate_postgres_materialized_view_ddls(&view, &request.target_schema) {
            if is_cancelled(&request.transfer_id).await {
                return Err("Cancelled".to_string());
            }
            completed_steps += 1;
            progress_callback(TransferProgress {
                transfer_id: request.transfer_id.clone(),
                table: format!("materialized view: {}", view.view_name),
                table_index,
                total_tables: request.tables.len(),
                rows_transferred: completed_steps,
                total_rows: Some(total_steps as u64),
                status: TransferStatus::Running,
                error: None,
                terminal: false,
            });
            execute_on_pool(state, target_pool_key, &statement)
                .await
                .map_err(|e| format!("Failed to create PostgreSQL materialized view {}: {e}", view.view_name))?;
        }
        outcome.transferred.push(format!("MaterializedView:{}", view.view_name));
    }

    for trigger in trigger_sources {
        if is_cancelled(&request.transfer_id).await {
            return Err("Cancelled".to_string());
        }
        let exists_sql = target_object_exists_sql(
            &DatabaseType::Postgres,
            &request.target_schema,
            &trigger.trigger_name,
            &TransferObjectKind::Trigger,
        )?;
        let exists = !execute_on_pool(state, target_pool_key, &exists_sql).await?.rows.is_empty();
        if exists {
            outcome.skipped.push(format!("Trigger:{}", trigger.trigger_name));
            continue;
        }
        completed_steps += 1;
        progress_callback(TransferProgress {
            transfer_id: request.transfer_id.clone(),
            table: format!("trigger: {}", trigger.trigger_name),
            table_index,
            total_tables: request.tables.len(),
            rows_transferred: completed_steps,
            total_rows: Some(total_steps as u64),
            status: TransferStatus::Running,
            error: None,
            terminal: false,
        });
        let full_table = qualified_table(&trigger.table_name, &request.target_schema, &DatabaseType::Postgres, None);
        let drop_sql = format!(
            "DROP TRIGGER IF EXISTS {} ON {full_table}",
            quote_identifier(&trigger.trigger_name, &DatabaseType::Postgres)
        );
        execute_on_pool(state, target_pool_key, &drop_sql)
            .await
            .map_err(|e| format!("Failed to drop PostgreSQL trigger {}: {e}", trigger.trigger_name))?;
        completed_steps += 1;
        progress_callback(TransferProgress {
            transfer_id: request.transfer_id.clone(),
            table: format!("trigger: {}", trigger.trigger_name),
            table_index,
            total_tables: request.tables.len(),
            rows_transferred: completed_steps,
            total_rows: Some(total_steps as u64),
            status: TransferStatus::Running,
            error: None,
            terminal: false,
        });
        let create_sql = rewrite_postgres_trigger_table_schema(
            &ensure_sql_statement_terminated(&trigger.source),
            &request.source_schema,
            &trigger.table_name,
            &request.target_schema,
        );
        execute_on_pool(state, target_pool_key, &create_sql)
            .await
            .map_err(|e| format!("Failed to create PostgreSQL trigger {}: {e}", trigger.trigger_name))?;
        outcome.transferred.push(format!("Trigger:{}", trigger.trigger_name));
    }

    for statement in policy_statements {
        if is_cancelled(&request.transfer_id).await {
            return Err("Cancelled".to_string());
        }
        completed_steps += 1;
        progress_callback(TransferProgress {
            transfer_id: request.transfer_id.clone(),
            table: "row security policies".to_string(),
            table_index,
            total_tables: request.tables.len(),
            rows_transferred: completed_steps,
            total_rows: Some(total_steps as u64),
            status: TransferStatus::Running,
            error: None,
            terminal: false,
        });
        execute_on_pool(state, target_pool_key, &statement)
            .await
            .map_err(|e| format!("Failed to apply PostgreSQL row security statement: {e}"))?;
    }

    for statement in ownership_statements {
        if is_cancelled(&request.transfer_id).await {
            return Err("Cancelled".to_string());
        }
        completed_steps += 1;
        progress_callback(TransferProgress {
            transfer_id: request.transfer_id.clone(),
            table: "ownership".to_string(),
            table_index,
            total_tables: request.tables.len(),
            rows_transferred: completed_steps,
            total_rows: Some(total_steps as u64),
            status: TransferStatus::Running,
            error: None,
            terminal: false,
        });
        let ownership_owner = if matches!(request.ownership_policy, TransferOwnershipPolicy::ReassignMissing)
            && !ownership_existing_roles.contains(&statement.owner)
        {
            ownership_target_user
                .as_deref()
                .ok_or_else(|| "Failed to read target PostgreSQL current user".to_string())?
        } else {
            &statement.owner
        };
        let ownership_sql = build_postgres_ownership_statement(&statement, ownership_owner);
        execute_on_pool(state, target_pool_key, &ownership_sql)
            .await
            .map_err(|e| format!("Failed to apply PostgreSQL ownership statement: {e}"))?;
    }

    for statement in grant_statements {
        if is_cancelled(&request.transfer_id).await {
            return Err("Cancelled".to_string());
        }
        completed_steps += 1;
        progress_callback(TransferProgress {
            transfer_id: request.transfer_id.clone(),
            table: "grants".to_string(),
            table_index,
            total_tables: request.tables.len(),
            rows_transferred: completed_steps,
            total_rows: Some(total_steps as u64),
            status: TransferStatus::Running,
            error: None,
            terminal: false,
        });
        execute_on_pool(state, target_pool_key, &statement)
            .await
            .map_err(|e| format!("Failed to apply PostgreSQL grant statement: {e}"))?;
    }

    Ok(outcome)
}

#[cfg(test)]
mod tests {
    use super::*;
    use serde_json::json;

    fn test_column(name: &str, data_type: &str) -> db::ColumnInfo {
        db::ColumnInfo {
            name: name.to_string(),
            data_type: data_type.to_string(),
            is_nullable: true,
            column_default: None,
            is_primary_key: false,
            extra: None,
            comment: None,
            numeric_precision: None,
            numeric_scale: None,
            character_maximum_length: None,
            enum_values: None,
            ..Default::default()
        }
    }

    fn test_table(name: &str) -> db::TableInfo {
        db::TableInfo {
            name: name.to_string(),
            table_type: "TABLE".to_string(),
            comment: None,
            parent_schema: None,
            parent_name: None,
        }
    }

    fn test_query_result(rows: Vec<Vec<serde_json::Value>>) -> db::QueryResult {
        db::QueryResult {
            columns: Vec::new(),
            column_types: Vec::new(),
            column_sortables: Vec::new(),
            spatial_columns: vec![],
            spatial_values: vec![],
            rows,
            affected_rows: 0,
            execution_time_ms: 0,
            truncated: false,
            session_id: None,
            has_more: false,
            elasticsearch_raw_body: None,
            messages: Vec::new(),
        }
    }

    #[test]
    fn table_dependency_sort_places_parents_before_children() {
        let tables = vec!["audit".to_string(), "users".to_string(), "orders".to_string()];
        let dependencies =
            vec![("audit".to_string(), "orders".to_string()), ("orders".to_string(), "users".to_string())];

        assert_eq!(
            sort_table_names_by_dependencies(&tables, &dependencies, true),
            vec!["users".to_string(), "orders".to_string(), "audit".to_string()]
        );
        assert_eq!(
            sort_table_names_by_dependencies(&tables, &dependencies, false),
            vec!["audit".to_string(), "orders".to_string(), "users".to_string()]
        );
    }

    #[test]
    fn table_dependency_sort_ignores_duplicates_and_out_of_scope_tables() {
        let tables = vec!["orders".to_string(), "users".to_string(), "logs".to_string()];
        let dependencies = vec![
            ("orders".to_string(), "users".to_string()),
            ("orders".to_string(), "users".to_string()),
            ("logs".to_string(), "external_users".to_string()),
        ];

        assert_eq!(
            sort_table_names_by_dependencies(&tables, &dependencies, true),
            vec!["users".to_string(), "logs".to_string(), "orders".to_string()]
        );
    }

    #[test]
    fn postgres_dependency_batch_query_keeps_agent_fallback() {
        let agent = PoolKind::agent(crate::db::agent_driver::AgentDriverClient::test_stub());

        assert!(native_postgres_dependency_pool(Some(&agent)).is_none());
    }

    async fn test_app_state() -> (AppState, std::path::PathBuf) {
        let dir = std::env::temp_dir().join(format!("dbx-transfer-test-{}", uuid::Uuid::new_v4()));
        std::fs::create_dir_all(&dir).unwrap();
        let storage = crate::storage::Storage::open(&dir.join("storage.db")).await.unwrap();
        (AppState::new(storage), dir)
    }

    #[tokio::test]
    async fn postgres_transfer_metadata_routes_agent_pools() {
        let (state, dir) = test_app_state().await;
        state.connections.write().await.insert(
            "source:source_db".to_string(),
            PoolKind::agent(crate::db::agent_driver::AgentDriverClient::test_stub()),
        );

        let index_error =
            get_postgres_indexes_for_transfer(&state, "source:source_db", "source_db", "source_schema", "items")
                .await
                .unwrap_err();
        let foreign_key_error =
            get_postgres_foreign_keys_for_transfer(&state, "source:source_db", "source_db", "source_schema", "items")
                .await
                .unwrap_err();

        assert!(!index_error.contains("PostgreSQL pool not found"), "index error: {index_error}");
        assert!(!foreign_key_error.contains("PostgreSQL pool not found"), "foreign key error: {foreign_key_error}");
        let _ = std::fs::remove_dir_all(dir);
    }

    #[test]
    fn postgres_schema_exists_query_escapes_schema_name() {
        assert_eq!(
            postgres_schema_exists_sql("team's data"),
            "SELECT 1 FROM pg_catalog.pg_namespace WHERE nspname = 'team''s data' LIMIT 1"
        );
    }

    #[test]
    fn postgres_schema_exists_depends_on_returned_rows() {
        assert!(!query_result_has_rows(&test_query_result(Vec::new())));
        assert!(query_result_has_rows(&test_query_result(vec![vec![serde_json::json!(1)]])));
    }

    #[test]
    fn transfer_content_defaults_to_structure_and_data() {
        let request: TransferRequest = serde_json::from_value(serde_json::json!({
            "transferId": "t1", "sourceConnectionId": "s", "sourceDatabase": "db",
            "sourceSchema": "public", "targetConnectionId": "t", "targetDatabase": "db",
            "targetSchema": "public", "tables": ["a"], "createTable": true,
            "mode": "append", "targetTableNameCase": "preserve", "batchSize": 1000
        }))
        .unwrap();
        assert_eq!(request.content, TransferContent::StructureAndData);
        assert!(request.objects.is_empty());
    }

    #[test]
    fn transfer_request_serializes_new_fields_camel_case() {
        let request = TransferRequest {
            transfer_id: "t1".to_string(),
            source_connection_id: "s".to_string(),
            source_database: "db".to_string(),
            source_schema: "public".to_string(),
            source_catalog: None,
            target_connection_id: "t".to_string(),
            target_database: "db".to_string(),
            target_schema: "public".to_string(),
            target_catalog: None,
            tables: vec!["a".to_string()],
            create_table: true,
            content: TransferContent::StructureOnly,
            objects: vec![TransferObjectSelection {
                object_type: TransferObjectKind::View,
                names: vec!["v1".to_string()],
            }],
            mode: TransferMode::Append,
            target_table_name_case: TransferTableNameCase::Preserve,
            ownership_policy: TransferOwnershipPolicy::Preserve,
            batch_size: 1000,
        };
        let json = serde_json::to_value(&request).unwrap();
        assert_eq!(json["content"], "structureOnly");
        assert_eq!(json["objects"][0]["objectType"], "VIEW");
        assert_eq!(json["objects"][0]["names"][0], "v1");
    }

    mod transfer_family_tests {
        use super::*;

        #[test]
        fn same_family_matrix() {
            // postgres family
            assert!(is_same_transfer_family(&DatabaseType::Postgres, &DatabaseType::Kingbase));
            assert!(is_same_transfer_family(&DatabaseType::Gaussdb, &DatabaseType::OpenGauss));
            // oracle family
            assert!(is_same_transfer_family(&DatabaseType::Oracle, &DatabaseType::Dameng));
            assert!(is_same_transfer_family(&DatabaseType::OceanbaseOracle, &DatabaseType::Dameng));
            // mysql
            assert!(is_same_transfer_family(&DatabaseType::Mysql, &DatabaseType::Mysql));
            // sqlserver
            assert!(is_same_transfer_family(&DatabaseType::SqlServer, &DatabaseType::SqlServer));
            // cross family
            assert!(!is_same_transfer_family(&DatabaseType::Mysql, &DatabaseType::Postgres));
            assert!(!is_same_transfer_family(&DatabaseType::Mysql, &DatabaseType::SqlServer));
        }

        #[test]
        fn object_kinds_per_family() {
            let mysql = transfer_object_kinds(&DatabaseType::Mysql);
            assert!(mysql.contains(&TransferObjectKind::Event));
            assert!(!mysql.contains(&TransferObjectKind::Sequence));
            let pg = transfer_object_kinds(&DatabaseType::Postgres);
            assert!(pg.contains(&TransferObjectKind::Sequence));
            assert!(!pg.contains(&TransferObjectKind::Event));
            let dm = transfer_object_kinds(&DatabaseType::Dameng);
            assert!(dm.contains(&TransferObjectKind::Trigger));
            assert!(dm.contains(&TransferObjectKind::Sequence));
            let sqlserver = transfer_object_kinds(&DatabaseType::SqlServer);
            assert!(sqlserver.contains(&TransferObjectKind::View));
            assert!(sqlserver.contains(&TransferObjectKind::Procedure));
            assert!(sqlserver.contains(&TransferObjectKind::Function));
            assert!(sqlserver.contains(&TransferObjectKind::Trigger));
            assert!(sqlserver.contains(&TransferObjectKind::Sequence));
            assert!(!sqlserver.contains(&TransferObjectKind::Event));
            assert!(!sqlserver.contains(&TransferObjectKind::MaterializedView));
            assert!(transfer_object_kinds(&DatabaseType::Sqlite).is_empty());
        }
    }

    mod transfer_validation_tests {
        use super::*;

        #[test]
        fn validates_content_and_object_rules() {
            let base = TransferRequest {
                transfer_id: "t".into(),
                source_connection_id: "s".into(),
                source_database: "db".into(),
                source_schema: "public".into(),
                source_catalog: None,
                target_connection_id: "t".into(),
                target_database: "db".into(),
                target_schema: "public".into(),
                target_catalog: None,
                tables: vec!["a".into()],
                create_table: true,
                mode: TransferMode::Append,
                target_table_name_case: TransferTableNameCase::Preserve,
                ownership_policy: TransferOwnershipPolicy::Preserve,
                batch_size: 1000,
                content: TransferContent::DataOnly,
                objects: Vec::new(),
            };
            assert!(validate_transfer_request(&base).is_ok());

            let with_objects = TransferRequest {
                objects: vec![TransferObjectSelection {
                    object_type: TransferObjectKind::View,
                    names: vec!["v".into()],
                }],
                ..base.clone()
            };
            // DataOnly + objects → error
            assert!(validate_transfer_request(&with_objects).is_err());

            let structure_only = TransferRequest { content: TransferContent::StructureOnly, ..base.clone() };
            assert!(validate_transfer_request(&structure_only).is_ok());
        }
    }

    mod transfer_existence_tests {
        use super::*;

        #[test]
        fn builds_target_existence_check_sql_per_family() {
            let mysql =
                target_object_exists_sql(&DatabaseType::Mysql, "shop", "v1", &TransferObjectKind::View).unwrap();
            assert!(mysql.contains("information_schema.TABLES"));
            assert!(mysql.contains("TABLE_TYPE = 'VIEW'"));
            let mysql_ev =
                target_object_exists_sql(&DatabaseType::Mysql, "shop", "e1", &TransferObjectKind::Event).unwrap();
            assert!(mysql_ev.contains("information_schema.EVENTS"));
            let mysql_tr =
                target_object_exists_sql(&DatabaseType::Mysql, "shop", "t1", &TransferObjectKind::Trigger).unwrap();
            assert!(mysql_tr.contains("information_schema.TRIGGERS"));
            let pg =
                target_object_exists_sql(&DatabaseType::Postgres, "public", "v1", &TransferObjectKind::View).unwrap();
            assert!(pg.contains("pg_class"));
            let orc =
                target_object_exists_sql(&DatabaseType::Oracle, "HR", "SEQ1", &TransferObjectKind::Sequence).unwrap();
            assert!(orc.contains("ALL_OBJECTS"));
            assert!(target_object_exists_sql(&DatabaseType::Sqlite, "m", "x", &TransferObjectKind::View).is_err());
            let ss_view =
                target_object_exists_sql(&DatabaseType::SqlServer, "dbo", "v1", &TransferObjectKind::View).unwrap();
            assert!(ss_view.contains("sys.objects"));
            assert!(ss_view.contains("o.type IN ('V')"));
            let ss_seq =
                target_object_exists_sql(&DatabaseType::SqlServer, "dbo", "s1", &TransferObjectKind::Sequence).unwrap();
            assert!(ss_seq.contains("o.type IN ('SO')"));
            let ss_trg =
                target_object_exists_sql(&DatabaseType::SqlServer, "dbo", "t1", &TransferObjectKind::Trigger).unwrap();
            assert!(ss_trg.contains("o.type IN ('TR')"));
        }
    }

    mod transfer_cross_family_tests {
        use super::*;
        use TransferObjectKind::*;

        #[test]
        fn cross_family_transferable_kinds_matrix() {
            // cross-family VIEW transfer is disabled (the DDL conversion does
            // not translate the view query body, so source-specific constructs
            // could run unchanged on an incompatible target)
            assert!(cross_family_transferable_object_kinds(&DatabaseType::Mysql, &DatabaseType::Dameng).is_empty());
            assert!(cross_family_transferable_object_kinds(&DatabaseType::Dameng, &DatabaseType::Mysql).is_empty());
            assert!(cross_family_transferable_object_kinds(&DatabaseType::Mysql, &DatabaseType::SqlServer).is_empty());
            // sqlserver <-> dameng: sequences only (plain DDL, converted and tested)
            assert_eq!(
                cross_family_transferable_object_kinds(&DatabaseType::SqlServer, &DatabaseType::Dameng),
                vec![Sequence]
            );
            assert_eq!(
                cross_family_transferable_object_kinds(&DatabaseType::Dameng, &DatabaseType::SqlServer),
                vec![Sequence]
            );
            // same family: all source kinds are transferable
            let same = cross_family_transferable_object_kinds(&DatabaseType::Mysql, &DatabaseType::Mysql);
            assert!(same.contains(&Trigger));
            assert!(same.contains(&Event));
            // unsupported databases
            assert!(cross_family_transferable_object_kinds(&DatabaseType::Sqlite, &DatabaseType::Mysql).is_empty());
            // postgres is not a validated cross-family source or target:
            // the executor rejects postgres sources and no dialect-aware
            // conversion exists for it (postgres <-> postgres stays same-family)
            assert!(cross_family_transferable_object_kinds(&DatabaseType::Postgres, &DatabaseType::Mysql).is_empty());
            assert!(cross_family_transferable_object_kinds(&DatabaseType::Mysql, &DatabaseType::Postgres).is_empty());
            assert!(
                cross_family_transferable_object_kinds(&DatabaseType::Postgres, &DatabaseType::SqlServer).is_empty()
            );
            assert!(cross_family_transferable_object_kinds(&DatabaseType::Postgres, &DatabaseType::Postgres)
                .contains(&View));
        }

        #[test]
        fn should_transfer_schema_objects_matrix() {
            // DataOnly never transfers schema objects, even for PG-family pairs.
            assert!(!should_transfer_schema_objects(
                &DatabaseType::Postgres,
                &DatabaseType::Postgres,
                &TransferContent::DataOnly,
                &[]
            ));
            assert!(!should_transfer_schema_objects(
                &DatabaseType::Postgres,
                &DatabaseType::Postgres,
                &TransferContent::DataOnly,
                &[TransferObjectSelection { object_type: TransferObjectKind::View, names: vec!["v1".into()] }]
            ));
            assert!(!should_transfer_schema_objects(
                &DatabaseType::Mysql,
                &DatabaseType::Dameng,
                &TransferContent::DataOnly,
                &[TransferObjectSelection { object_type: TransferObjectKind::View, names: vec!["v1".into()] }]
            ));
            // Non-empty selections participate in structure modes.
            assert!(should_transfer_schema_objects(
                &DatabaseType::Postgres,
                &DatabaseType::Mysql,
                &TransferContent::StructureOnly,
                &[TransferObjectSelection { object_type: TransferObjectKind::View, names: vec!["v1".into()] }]
            ));
            // Empty selection: PG→PG keeps the legacy transfer-everything default
            // only when structure participates in the transfer.
            assert!(should_transfer_schema_objects(
                &DatabaseType::Postgres,
                &DatabaseType::Postgres,
                &TransferContent::StructureOnly,
                &[]
            ));
            assert!(should_transfer_schema_objects(
                &DatabaseType::Kingbase,
                &DatabaseType::Postgres,
                &TransferContent::StructureAndData,
                &[]
            ));
            assert!(should_transfer_schema_objects(
                &DatabaseType::Postgres,
                &DatabaseType::OpenGauss,
                &TransferContent::StructureOnly,
                &[]
            ));
            // empty selection: every other combination transfers nothing
            assert!(!should_transfer_schema_objects(
                &DatabaseType::Postgres,
                &DatabaseType::Mysql,
                &TransferContent::StructureOnly,
                &[]
            ));
            assert!(!should_transfer_schema_objects(
                &DatabaseType::Mysql,
                &DatabaseType::Mysql,
                &TransferContent::StructureAndData,
                &[]
            ));
            assert!(!should_transfer_schema_objects(
                &DatabaseType::Mysql,
                &DatabaseType::Dameng,
                &TransferContent::StructureOnly,
                &[]
            ));
            assert!(!should_transfer_schema_objects(
                &DatabaseType::Dameng,
                &DatabaseType::SqlServer,
                &TransferContent::StructureAndData,
                &[]
            ));
            assert!(!should_transfer_schema_objects(
                &DatabaseType::Sqlite,
                &DatabaseType::Sqlite,
                &TransferContent::StructureOnly,
                &[]
            ));
        }

        #[test]
        fn rewrites_cross_family_view_ddl() {
            // mysql -> dameng
            let mysql_view = "CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`%` SQL SECURITY DEFINER VIEW `src`.`v` AS select `t`.`id` AS `id` from `src`.`t`";
            let dm = convert_cross_family_object_ddl(
                &TransferObjectFamily::Mysql,
                &TransferObjectFamily::Oracle,
                &TransferObjectKind::View,
                "src",
                "TGT",
                mysql_view,
            );
            assert!(dm.starts_with("CREATE VIEW \"TGT\".\"v\" AS"), "{dm}");
            assert!(!dm.contains("DEFINER"));
            assert!(!dm.contains("ALGORITHM"));
            assert!(dm.contains("\"t\".\"id\""));
            assert!(dm.contains("from \"TGT\".\"t\""));

            // sqlserver -> mysql
            let ss_view = "CREATE VIEW [dbo].[v] WITH SCHEMABINDING AS SELECT a.id, b.name FROM [dbo].[a] JOIN [dbo].[b] ON a.id = b.id";
            let my = convert_cross_family_object_ddl(
                &TransferObjectFamily::SqlServer,
                &TransferObjectFamily::Mysql,
                &TransferObjectKind::View,
                "dbo",
                "tgt",
                ss_view,
            );
            assert!(my.starts_with("CREATE VIEW `tgt`.`v` AS"), "{my}");
            assert!(!my.contains("SCHEMABINDING"));
            assert!(my.contains("`tgt`.`a`"));
            assert!(!my.contains("["));

            // dameng -> sqlserver
            let dm_view = "CREATE OR REPLACE FORCE VIEW \"S\".\"V\" (\"ID\") AS SELECT \"ID\" FROM \"S\".\"T\"";
            let ss = convert_cross_family_object_ddl(
                &TransferObjectFamily::Oracle,
                &TransferObjectFamily::SqlServer,
                &TransferObjectKind::View,
                "S",
                "dbo",
                dm_view,
            );
            assert!(ss.starts_with("CREATE VIEW [dbo].[V] ("), "{ss}");
            assert!(!ss.contains("FORCE"));
            assert!(ss.contains("[dbo].[T]"));

            // dameng -> mysql
            let my2 = convert_cross_family_object_ddl(
                &TransferObjectFamily::Oracle,
                &TransferObjectFamily::Mysql,
                &TransferObjectKind::View,
                "S",
                "tgt",
                dm_view,
            );
            assert!(my2.starts_with("CREATE VIEW `tgt`.`V` ("), "{my2}");
            assert!(my2.contains("`tgt`.`T`"));
        }

        #[test]
        fn does_not_rewrite_identifiers_inside_strings_and_comments() {
            // MySQL -> Dameng: string literals and comments must not have
            // their content re-quoted or schema-qualified.
            let mysql_view = concat!(
                "CREATE DEFINER=`root`@`%` VIEW `v` AS ",
                "-- from `hidden`.`table` join \"hidden\"\n",
                "SELECT `t`.`id`, 'from \"lit\"', \"double\" ",
                "/* join \"quoted\" */ FROM `src`.`t` ",
                "WHERE `t`.`name` = 'join \"src\".\"t\"'",
            );
            let dm = convert_cross_family_object_ddl(
                &TransferObjectFamily::Mysql,
                &TransferObjectFamily::Oracle,
                &TransferObjectKind::View,
                "src",
                "TGT",
                mysql_view,
            );
            assert!(dm.starts_with("CREATE VIEW \"TGT\".\"v\" AS"), "{dm}");
            // code identifiers are rewritten and qualified
            assert!(dm.contains("SELECT \"t\".\"id\""), "{dm}");
            assert!(dm.contains("FROM \"TGT\".\"t\""), "{dm}");
            // the comment is untouched
            assert!(dm.contains("-- from `hidden`.`table` join \"hidden\""), "{dm}");
            assert!(dm.contains("/* join \"quoted\" */"), "{dm}");
            // the single-quoted string literal is untouched (including the
            // fake qualifier inside it)
            assert!(dm.contains("'join \"src\".\"t\"'"), "{dm}");
            // MySQL double-quoted text is a string literal, not an identifier
            assert!(dm.contains("\"double\""), "{dm}");

            // SqlServer -> MySQL: brackets inside comments/strings stay put
            let ss_view = concat!(
                "CREATE VIEW [dbo].[v] AS ",
                "-- SELECT [dbo].[x]\n",
                "SELECT [a].[id], 'literal [dbo].[y]' FROM [dbo].[a]",
            );
            let my = convert_cross_family_object_ddl(
                &TransferObjectFamily::SqlServer,
                &TransferObjectFamily::Mysql,
                &TransferObjectKind::View,
                "dbo",
                "tgt",
                ss_view,
            );
            assert!(my.starts_with("CREATE VIEW `tgt`.`v` AS"), "{my}");
            assert!(my.contains("`tgt`.`a`"), "{my}");
            assert!(my.contains("-- SELECT [dbo].[x]"), "{my}");
            assert!(my.contains("'literal [dbo].[y]'"), "{my}");
        }

        #[test]
        fn sequence_rewrite_keeps_strings_intact() {
            // SqlServer -> Dameng: `AS BIGINT` stripping must not touch a
            // string literal that merely contains the token.
            let ss_seq = "CREATE SEQUENCE [dbo].[s] AS BIGINT START WITH 1 COMMENT 'AS BIGINT in comment'";
            let dm = convert_cross_family_object_ddl(
                &TransferObjectFamily::SqlServer,
                &TransferObjectFamily::Oracle,
                &TransferObjectKind::Sequence,
                "dbo",
                "TGT",
                ss_seq,
            );
            assert!(dm.starts_with("CREATE SEQUENCE \"TGT\".\"s\" START WITH 1"), "{dm}");
            assert!(!dm.contains("\"s\" AS BIGINT"), "{dm}");
            assert!(dm.contains("'AS BIGINT in comment'"), "{dm}");
        }

        #[test]
        fn rewrites_cross_family_sequence_ddl() {
            // sqlserver -> dameng: strip AS type
            let ss_seq =
                "CREATE SEQUENCE [dbo].[seq1] AS BIGINT START WITH 5 INCREMENT BY 2 MINVALUE 1 MAXVALUE 1000 CACHE 50";
            let dm = convert_cross_family_object_ddl(
                &TransferObjectFamily::SqlServer,
                &TransferObjectFamily::Oracle,
                &TransferObjectKind::Sequence,
                "dbo",
                "TGT",
                ss_seq,
            );
            assert!(dm.starts_with("CREATE SEQUENCE \"TGT\".\"seq1\" START WITH 5"), "{dm}");
            assert!(!dm.contains("AS BIGINT"));
            assert!(dm.contains("CACHE 50"));

            // dameng -> sqlserver: NO CYCLE spacing
            let dm_seq = "CREATE SEQUENCE \"S\".\"SEQ1\" START WITH 1 INCREMENT BY 1 MINVALUE 1 NOCYCLE NOCACHE";
            let ss = convert_cross_family_object_ddl(
                &TransferObjectFamily::Oracle,
                &TransferObjectFamily::SqlServer,
                &TransferObjectKind::Sequence,
                "S",
                "dbo",
                dm_seq,
            );
            assert!(ss.starts_with("CREATE SEQUENCE [dbo].[SEQ1]"), "{ss}");
            assert!(ss.contains("NO CYCLE"), "{ss}");
            assert!(ss.contains("NO CACHE"), "{ss}");
        }

        #[test]
        fn rejects_unsupported_cross_family_objects_in_executor() {
            let kinds = cross_family_transferable_object_kinds(&DatabaseType::Mysql, &DatabaseType::SqlServer);
            // VIEW is disabled cross-family: only the DDL wrapper/quoting is
            // rewritten, the query body is not translated
            assert!(!kinds.contains(&View));
            // procedures/triggers are never cross-family transferable
            assert!(!kinds.contains(&Procedure));
            assert!(!kinds.contains(&Trigger));
            assert!(!kinds.contains(&Event));
            assert!(!kinds.contains(&Function));
        }

        #[test]
        fn qualifies_cross_family_view_target_schema() {
            // mysql -> dameng: bare refs get the target schema prefix, prefixed
            // refs keep their (rewritten) prefix
            let mysql_view = "CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`%` SQL SECURITY DEFINER VIEW `v` AS select a.id from `exam_record` a join `exam`.`t2` t on t.id = a.id";
            let dm = convert_cross_family_object_ddl(
                &TransferObjectFamily::Mysql,
                &TransferObjectFamily::Oracle,
                &TransferObjectKind::View,
                "exam",
                "DM",
                mysql_view,
            );
            assert!(dm.starts_with("CREATE VIEW \"DM\".\"v\" AS"), "{dm}");
            assert!(dm.contains("from \"DM\".\"exam_record\" a"), "{dm}");
            assert!(dm.contains("join \"DM\".\"t2\" t"), "{dm}");

            // dameng -> mysql: quoted prefix style switches to backticks
            let dm_view =
                "CREATE OR REPLACE FORCE NONEDITIONABLE VIEW \"DM\".\"v\" AS select id from \"DM\".\"exam_record\"";
            let my = convert_cross_family_object_ddl(
                &TransferObjectFamily::Oracle,
                &TransferObjectFamily::Mysql,
                &TransferObjectKind::View,
                "DM",
                "exam",
                dm_view,
            );
            assert!(my.starts_with("CREATE VIEW `exam`.`v` AS"), "{my}");
            assert!(my.contains("from `exam`.`exam_record`"), "{my}");

            // sqlserver -> dameng
            let ss_view = "CREATE VIEW [dbo].[v] WITH SCHEMABINDING AS select id from [dbo].[exam_record]";
            let dm2 = convert_cross_family_object_ddl(
                &TransferObjectFamily::SqlServer,
                &TransferObjectFamily::Oracle,
                &TransferObjectKind::View,
                "dbo",
                "TGT",
                ss_view,
            );
            assert!(dm2.starts_with("CREATE VIEW \"TGT\".\"v\" AS"), "{dm2}");
            assert!(dm2.contains("from \"TGT\".\"exam_record\""), "{dm2}");
        }

        #[test]
        fn qualifies_cross_family_view_with_cjk_identifiers() {
            // mysql -> dameng with Chinese table/view names
            let mysql_view = "CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`%` SQL SECURITY DEFINER VIEW `成绩排名` AS select a.id from `用户表` a join `exam`.`成绩明细` t on t.id = a.id";
            let dm = convert_cross_family_object_ddl(
                &TransferObjectFamily::Mysql,
                &TransferObjectFamily::Oracle,
                &TransferObjectKind::View,
                "exam",
                "DM",
                mysql_view,
            );
            assert!(dm.starts_with("CREATE VIEW \"DM\".\"成绩排名\" AS"), "{dm}");
            assert!(dm.contains("from \"DM\".\"用户表\" a"), "{dm}");
            assert!(dm.contains("join \"DM\".\"成绩明细\" t"), "{dm}");
        }
    }
    mod transfer_mysql_ddl_tests {
        use super::*;

        #[test]
        fn strips_mysql_definer_clauses() {
            assert_eq!(strip_mysql_definer("CREATE DEFINER=`u`@`%` VIEW v AS SELECT 1"), "CREATE VIEW v AS SELECT 1");
            assert_eq!(
                strip_mysql_definer("CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` VIEW v AS SELECT 1"),
                "CREATE ALGORITHM=UNDEFINED VIEW v AS SELECT 1"
            );
            assert_eq!(strip_mysql_definer("CREATE PROCEDURE p() BEGIN END"), "CREATE PROCEDURE p() BEGIN END");
        }

        #[test]
        fn rewrites_mysql_schema_qualifiers() {
            assert_eq!(
                rewrite_mysql_schema_qualifier("CREATE VIEW `src`.`v` AS SELECT 1 FROM `src`.`t`", "src", "dst"),
                "CREATE VIEW `dst`.`v` AS SELECT 1 FROM `dst`.`t`"
            );
        }

        #[test]
        fn assembles_mysql_trigger_and_event_ddl() {
            let trigger = mysql_trigger_ddl("shop", "trg1", "BEFORE", "INSERT", "users", "SET NEW.updated = NOW()");
            assert_eq!(
                trigger,
                "CREATE TRIGGER `trg1` BEFORE INSERT ON `shop`.`users` FOR EACH ROW SET NEW.updated = NOW()"
            );
            let event = mysql_event_ddl("shop", "ev1", "ENABLE", "EVERY 1 DAY", "DELETE FROM logs");
            assert_eq!(event, "CREATE EVENT `ev1` ON SCHEDULE EVERY 1 DAY ENABLE DO DELETE FROM logs");
        }
    }

    mod transfer_sqlserver_source_tests {
        use super::*;
        use serde_json::json;

        #[test]
        fn builds_sqlserver_object_source_queries() {
            let view = sqlserver_object_source_query(&TransferObjectKind::View, "dbo", "v1").unwrap();
            assert!(view.contains("sys.sql_modules"), "{view}");
            assert!(view.contains("o.type IN ('V')"), "{view}");
            let routine = sqlserver_object_source_query(&TransferObjectKind::Procedure, "dbo", "p1").unwrap();
            assert!(routine.contains("o.type IN ('P')"), "{routine}");
            let trigger = sqlserver_object_source_query(&TransferObjectKind::Trigger, "dbo", "t1").unwrap();
            assert!(trigger.contains("o.type IN ('TR')"), "{trigger}");
            let seq = sqlserver_object_source_query(&TransferObjectKind::Sequence, "dbo", "s1").unwrap();
            assert!(seq.contains("sys.sequences"), "{seq}");
            assert!(!seq.contains("sys.sql_modules"), "{seq}");
        }

        #[test]
        fn extracts_sqlserver_object_ddl_from_result() {
            let view_result = test_query_result(vec![vec![json!("CREATE VIEW [dbo].[v1] AS SELECT 1 AS x")]]);
            let ddl = sqlserver_object_ddl_from_result(&view_result, "dbo", "v1", &TransferObjectKind::View).unwrap();
            assert_eq!(ddl, "CREATE VIEW [dbo].[v1] AS SELECT 1 AS x");

            // start, increment, min, max, cycle, cache
            let seq_result = test_query_result(vec![vec![
                json!("1"),
                json!("2"),
                json!("5"),
                json!("1000"),
                json!("NO CYCLE"),
                json!("50"),
            ]]);
            let seq_ddl =
                sqlserver_object_ddl_from_result(&seq_result, "dbo", "s1", &TransferObjectKind::Sequence).unwrap();
            assert!(
                seq_ddl.starts_with("CREATE SEQUENCE [dbo].[s1] START WITH 1 INCREMENT BY 2 MINVALUE 5 MAXVALUE 1000"),
                "{seq_ddl}"
            );
            assert!(seq_ddl.contains("NO CYCLE"), "{seq_ddl}");
            assert!(seq_ddl.contains("CACHE 50"), "{seq_ddl}");
        }
    }
    mod transfer_mysql_source_tests {
        use super::*;

        #[test]
        fn builds_mysql_object_source_queries() {
            let sql = mysql_object_source_query(&TransferObjectKind::View, "shop", "v1").unwrap();
            assert!(sql.contains("SHOW CREATE VIEW"));
            let sql = mysql_object_source_query(&TransferObjectKind::Trigger, "shop", "trg1").unwrap();
            assert!(sql.contains("information_schema.TRIGGERS"));
            assert!(sql.contains("TRIGGER_NAME = 'trg1'"));
            let sql = mysql_object_source_query(&TransferObjectKind::Event, "shop", "ev1").unwrap();
            assert!(sql.contains("information_schema.EVENTS"));
            assert!(sql.contains("EVENT_NAME = 'ev1'"));
        }

        #[test]
        fn extracts_mysql_object_ddl_from_result() {
            let view = mysql_object_ddl_from_result(
                &TransferObjectKind::View,
                "shop",
                &[vec![serde_json::json!("v1"), serde_json::json!("CREATE VIEW `shop`.`v1` AS SELECT 1")]],
            )
            .unwrap();
            assert_eq!(view, "CREATE VIEW `shop`.`v1` AS SELECT 1");

            let routine = mysql_object_ddl_from_result(
                &TransferObjectKind::Procedure,
                "shop",
                &[vec![
                    serde_json::json!("p"),
                    serde_json::json!("PROCEDURE"),
                    serde_json::json!("CREATE PROCEDURE p() BEGIN END"),
                ]],
            )
            .unwrap();
            assert_eq!(routine, "CREATE PROCEDURE p() BEGIN END");

            let trigger = mysql_object_ddl_from_result(
                &TransferObjectKind::Trigger,
                "shop",
                &[vec![
                    serde_json::json!("trg1"),
                    serde_json::json!("BEFORE"),
                    serde_json::json!("INSERT"),
                    serde_json::json!("users"),
                    serde_json::json!("SET NEW.updated = NOW()"),
                ]],
            )
            .unwrap();
            assert_eq!(
                trigger,
                "CREATE TRIGGER `trg1` BEFORE INSERT ON `shop`.`users` FOR EACH ROW SET NEW.updated = NOW()"
            );

            let event = mysql_object_ddl_from_result(
                &TransferObjectKind::Event,
                "shop",
                &[vec![
                    serde_json::json!("ev1"),
                    serde_json::json!("ENABLE"),
                    serde_json::json!("2026-01-01"),
                    serde_json::json!("1"),
                    serde_json::json!("DAY"),
                    serde_json::json!("DELETE FROM logs"),
                ]],
            )
            .unwrap();
            assert_eq!(event, "CREATE EVENT `ev1` ON SCHEDULE EVERY 1 DAY ENABLE DO DELETE FROM logs");
        }
    }

    mod transfer_oracle_source_tests {
        use super::*;

        #[test]
        fn builds_oracle_object_source_query() {
            let sql = oracle_object_source_query(&TransferObjectKind::Trigger, "HR", "TRG1").unwrap();
            assert!(sql.contains("DBMS_METADATA.GET_DDL('TRIGGER', 'TRG1', 'HR')"));
            let sql = oracle_object_source_query(&TransferObjectKind::Sequence, "HR", "SEQ1").unwrap();
            assert!(sql.contains("DBMS_METADATA.GET_DDL('SEQUENCE', 'SEQ1', 'HR')"));
            let sql = oracle_object_source_query(&TransferObjectKind::View, "", "V1").unwrap();
            assert!(!sql.contains(",'"));
        }

        #[test]
        fn rewrites_oracle_schema_qualifiers() {
            let ddl = "CREATE OR REPLACE TRIGGER \"HR\".\"TRG1\" ...";
            assert_eq!(
                rewrite_oracle_schema_qualifier(ddl, "HR", "APP"),
                "CREATE OR REPLACE TRIGGER \"APP\".\"TRG1\" ..."
            );
        }
    }

    mod transfer_executor_tests {
        use super::*;

        #[test]
        fn orders_object_selections_by_dependency() {
            let kinds = vec![
                TransferObjectKind::Trigger,
                TransferObjectKind::View,
                TransferObjectKind::Sequence,
                TransferObjectKind::Event,
                TransferObjectKind::Procedure,
                TransferObjectKind::Function,
            ];
            let ordered = ordered_transfer_object_kinds(kinds);
            assert_eq!(ordered[0], TransferObjectKind::Sequence);
            assert_eq!(ordered[1], TransferObjectKind::View);
            assert_eq!(ordered[2], TransferObjectKind::Function);
            assert_eq!(ordered[3], TransferObjectKind::Procedure);
            assert_eq!(ordered[4], TransferObjectKind::Trigger);
            assert_eq!(ordered[5], TransferObjectKind::Event);
        }
    }

    mod transfer_mysql_executor_tests {
        use super::*;

        #[test]
        fn extracts_selected_names_by_kind() {
            let selections = vec![
                TransferObjectSelection { object_type: TransferObjectKind::View, names: vec!["v1".into()] },
                TransferObjectSelection { object_type: TransferObjectKind::View, names: vec!["v2".into()] },
                TransferObjectSelection { object_type: TransferObjectKind::Trigger, names: vec!["t1".into()] },
            ];
            let views = selected_object_names(&selections, &TransferObjectKind::View);
            assert_eq!(views, vec!["v1", "v2"]);
            assert!(selected_object_names(&selections, &TransferObjectKind::Event).is_empty());
        }
    }

    mod transfer_oracle_executor_tests {
        use super::*;

        #[test]
        fn resolves_oracle_family_source_schema() {
            assert_eq!(resolve_oracle_schema("", "HR"), "HR");
            assert_eq!(resolve_oracle_schema("HR", "db"), "HR");
        }
    }

    mod transfer_postgres_executor_tests {
        use super::*;

        #[test]
        fn postgres_transfer_routine_catalog_probe_checks_prokind() {
            let sql = postgres_transfer_routine_catalog_capability_sql();

            assert!(sql.contains("attrelid = 'pg_catalog.pg_proc'::regclass"));
            assert!(sql.contains("attname = 'prokind'"));
            assert!(sql.contains("NOT attisdropped"));
        }

        #[test]
        fn postgres_transfer_routine_sources_support_legacy_catalogs() {
            let modern = postgres_transfer_routines_sql("public", true);
            assert!(modern.contains("CASE p.prokind WHEN 'p' THEN 'PROCEDURE' ELSE 'FUNCTION' END"));
            assert!(modern.contains("p.prokind IN ('p','f')"));
            assert!(!modern.contains("p.proisagg"));

            let legacy = postgres_transfer_routines_sql("public", false);
            assert!(!legacy.contains("prokind"));
            assert!(legacy.contains("'FUNCTION'"));
            assert!(legacy.contains("NOT p.proisagg"));
            assert!(legacy.contains("NOT p.proiswindow"));
        }

        #[test]
        fn postgres_transfer_ownership_supports_legacy_catalogs() {
            let modern = postgres_transfer_ownership_statements_sql("public", "archive", &["items".into()], true);
            assert!(modern.contains("CASE p.prokind WHEN 'p' THEN 'PROCEDURE' ELSE 'FUNCTION' END"));
            assert!(modern.contains("p.prokind IN ('p','f')"));

            let legacy = postgres_transfer_ownership_statements_sql("public", "archive", &["items".into()], false);
            assert!(!legacy.contains("prokind"));
            assert!(legacy.contains("'FUNCTION'"));
            assert!(legacy.contains("NOT p.proisagg"));
            assert!(legacy.contains("NOT p.proiswindow"));
        }

        #[test]
        fn postgres_transfer_grants_support_legacy_catalogs() {
            let modern = postgres_transfer_grant_statements_sql("public", "archive", &["items".into()], true);
            assert!(modern.contains("CASE p.prokind WHEN 'p' THEN 'PROCEDURE' ELSE 'FUNCTION' END"));
            assert!(modern.contains("p.prokind IN ('p','f')"));

            let legacy = postgres_transfer_grant_statements_sql("public", "archive", &["items".into()], false);
            assert!(!legacy.contains("prokind"));
            assert!(legacy.contains("'FUNCTION' AS routine_kind"));
            assert!(legacy.contains("NOT p.proisagg"));
            assert!(legacy.contains("NOT p.proiswindow"));
        }

        #[test]
        fn filters_postgres_object_sources_by_selection() {
            let sources = vec![
                db::ObjectSource {
                    name: "v1".into(),
                    object_type: db::ObjectSourceKind::View,
                    schema: Some("public".into()),
                    source: "SELECT 1".into(),
                    editable: None,
                },
                db::ObjectSource {
                    name: "v2".into(),
                    object_type: db::ObjectSourceKind::View,
                    schema: Some("public".into()),
                    source: "SELECT 2".into(),
                    editable: None,
                },
            ];
            let selection =
                vec![TransferObjectSelection { object_type: TransferObjectKind::View, names: vec!["v1".into()] }];
            let filtered = filter_object_sources_by_selection(sources, &selection);
            assert_eq!(filtered.len(), 1);
            assert_eq!(filtered[0].name, "v1");
        }

        #[test]
        fn selected_postgres_sequences_are_prepared_without_changing_default_requests() {
            let mut request = test_transfer_request(vec!["biz_banner"]);
            assert!(selected_postgres_sequence_names(&request).is_empty());

            request.objects = vec![
                TransferObjectSelection { object_type: TransferObjectKind::Table, names: vec!["biz_banner".into()] },
                TransferObjectSelection {
                    object_type: TransferObjectKind::Sequence,
                    names: vec!["biz_banner_id_seq".into(), "biz_banner_id_seq".into()],
                },
            ];

            assert_eq!(selected_postgres_sequence_names(&request), vec!["biz_banner_id_seq"]);
            assert_eq!(postgres_transfer_relation_names(&request), vec!["biz_banner", "biz_banner_id_seq"]);
            let sql = postgres_selected_sequences_sql("public", &selected_postgres_sequence_names(&request)).unwrap();
            assert!(sql.contains("c.relname IN ('biz_banner_id_seq')"));
            assert!(sql.contains("pg_sequence_last_value(c.oid)::text"));
        }

        #[test]
        fn postgres_selected_sequence_ddl_preserves_definition_and_value() {
            let sequence = PostgresTransferSequence {
                name: "biz_banner_id_seq".into(),
                data_type: "bigint".into(),
                start_value: "5".into(),
                min_value: "-10".into(),
                max_value: "999".into(),
                increment: "2".into(),
                cycle: true,
                cache_value: "7".into(),
                last_value: Some("41".into()),
            };

            assert_eq!(
                generate_postgres_transfer_sequence_create_ddl(&sequence, "archive"),
                "CREATE SEQUENCE IF NOT EXISTS \"archive\".\"biz_banner_id_seq\"\n  AS bigint\n  START WITH 5\n  INCREMENT BY 2\n  MINVALUE -10\n  MAXVALUE 999\n  CACHE 7\n  CYCLE"
            );
            assert_eq!(
                generate_postgres_transfer_sequence_setval_sql(&sequence, "archive"),
                Some("SELECT setval('\"archive\".\"biz_banner_id_seq\"', 41, true)".into())
            );

            let never_called = PostgresTransferSequence { last_value: None, ..sequence };
            assert_eq!(generate_postgres_transfer_sequence_setval_sql(&never_called, "archive"), None);
        }
    }

    mod transfer_content_mode_tests {
        use super::*;

        #[test]
        fn structure_only_skips_data_steps() {
            assert!(should_copy_data(&TransferContent::StructureAndData));
            assert!(should_copy_data(&TransferContent::DataOnly));
            assert!(!should_copy_data(&TransferContent::StructureOnly));
        }
    }
    fn test_transfer_request(tables: Vec<&str>) -> TransferRequest {
        TransferRequest {
            transfer_id: "transfer-1".to_string(),
            source_connection_id: "source".to_string(),
            source_database: "source_db".to_string(),
            source_schema: "source_schema".to_string(),
            source_catalog: None,
            target_connection_id: "target".to_string(),
            target_database: "target_db".to_string(),
            target_schema: "target_schema".to_string(),
            target_catalog: None,
            tables: tables.into_iter().map(str::to_string).collect(),
            create_table: true,
            content: TransferContent::default(),
            objects: Vec::new(),
            mode: TransferMode::Append,
            target_table_name_case: TransferTableNameCase::Preserve,
            ownership_policy: TransferOwnershipPolicy::Preserve,
            batch_size: 1000,
        }
    }

    #[test]
    fn transfer_request_defaults_preserve_table_name_case() {
        let request: TransferRequest = serde_json::from_value(json!({
            "transferId": "transfer-1",
            "sourceConnectionId": "source",
            "sourceDatabase": "source_db",
            "sourceSchema": "source_schema",
            "targetConnectionId": "target",
            "targetDatabase": "target_db",
            "targetSchema": "target_schema",
            "tables": ["ORDERS"],
            "createTable": true,
            "mode": "append",
            "batchSize": 1000
        }))
        .unwrap();

        assert_eq!(request.target_table_name_case, TransferTableNameCase::Preserve);
        assert_eq!(request.target_table_name("ORDERS"), "ORDERS");
    }

    #[test]
    fn transfer_existing_target_table_name_prefers_exact_case() {
        let tables = vec![test_table("orders"), test_table("Orders")];

        assert_eq!(existing_transfer_target_table_name("Orders", &tables, true), Some("Orders".to_string()));
    }

    #[test]
    fn transfer_existing_target_table_name_respects_case_sensitive_targets() {
        let tables = vec![test_table("Orders")];

        assert_eq!(existing_transfer_target_table_name("orders", &tables, false), None);
        assert_eq!(existing_transfer_target_table_name("orders", &tables, true), Some("Orders".to_string()));
    }

    #[test]
    fn transfer_existing_target_table_name_ignores_contains_matches() {
        let tables = vec![test_table("archived_orders"), test_table("orders_backup")];

        assert_eq!(existing_transfer_target_table_name("orders", &tables, true), None);
    }

    #[test]
    fn parses_mysql_lower_case_table_names_values() {
        let string_result = test_query_result(vec![vec![json!("lower_case_table_names"), json!("2")]]);
        let numeric_result = test_query_result(vec![vec![json!("lower_case_table_names"), json!(1)]]);
        let empty_result = test_query_result(Vec::new());

        assert_eq!(mysql_lower_case_table_names_from_result(&string_result), Some(2));
        assert_eq!(mysql_lower_case_table_names_from_result(&numeric_result), Some(1));
        assert_eq!(mysql_lower_case_table_names_from_result(&empty_result), None);
    }

    #[test]
    fn transfer_table_name_case_transforms_target_names() {
        let mut request = test_transfer_request(vec!["ORDERS"]);
        request.target_table_name_case = TransferTableNameCase::Lower;
        assert_eq!(request.target_table_name("ORDERS"), "orders");

        request.target_table_name_case = TransferTableNameCase::Upper;
        assert_eq!(request.target_table_name("orders"), "ORDERS");
    }

    #[test]
    fn transfer_table_name_case_detects_target_collisions() {
        let mut request = test_transfer_request(vec!["ORDERS", "orders"]);
        request.target_table_name_case = TransferTableNameCase::Lower;

        let error = validate_transfer_target_table_names(&request).unwrap_err();
        assert!(error.contains("both map to 'orders'"));
    }

    #[test]
    fn detects_identity_extras_for_selected_columns() {
        assert!(selected_columns_include_identity_extras(
            &[String::from("id"), String::from("name")],
            &[Some(String::from("identity")), None],
        ));
        assert!(selected_columns_include_identity_extras(
            &[String::from("id")],
            &[Some(String::from("auto_increment"))],
        ));
        assert!(!selected_columns_include_identity_extras(
            &[String::from("name")],
            &[None, Some(String::from("identity"))],
        ));
    }

    #[test]
    fn detects_selected_identity_columns_from_target_metadata() {
        let target_columns = vec![
            db::ColumnInfo { extra: Some("identity".to_string()), ..test_column("ID", "INT") },
            test_column("NAME", "VARCHAR(20)"),
        ];

        assert!(selected_columns_include_identity_columns(&[String::from("id")], &target_columns));
        assert!(!selected_columns_include_identity_columns(&[String::from("name")], &target_columns));
    }

    #[test]
    fn detects_selected_postgres_generated_always_identity_columns() {
        let target_columns = vec![
            db::ColumnInfo {
                name: "ID".to_string(),
                extra: Some("  GeNeRaTeD\tALWAYS  AS\nIDENTITY (start with 1 increment by 1)".to_string()),
                ..test_column("ID", "bigint")
            },
            db::ColumnInfo {
                extra: Some("generated by default as identity".to_string()),
                ..test_column("by_default_id", "bigint")
            },
            db::ColumnInfo {
                extra: Some("generated always as (quantity * 2) stored".to_string()),
                ..test_column("total", "bigint")
            },
            test_column("name", "text"),
        ];

        assert!(selected_columns_include_postgres_generated_always_identity_columns(
            &[String::from("id")],
            &target_columns
        ));
        assert!(!selected_columns_include_postgres_generated_always_identity_columns(
            &[String::from("by_default_id")],
            &target_columns
        ));
        assert!(!selected_columns_include_postgres_generated_always_identity_columns(
            &[String::from("total")],
            &target_columns
        ));
        assert!(!selected_columns_include_postgres_generated_always_identity_columns(
            &[String::from("name")],
            &target_columns
        ));
    }

    #[test]
    fn sqlserver_writable_transfer_columns_skip_rowversion_types() {
        let columns = vec![
            test_column("id", "int"),
            test_column("TimeSpan", "timestamp"),
            test_column("rv", "ROWVERSION"),
            test_column("name", "nvarchar(64)"),
        ];

        let writable = writable_transfer_columns(&columns, &DatabaseType::SqlServer, &DatabaseType::SqlServer);

        assert_eq!(writable.iter().map(|column| column.name.as_str()).collect::<Vec<_>>(), vec!["id", "name"]);
    }

    #[test]
    fn mysql_writable_transfer_columns_skip_only_generated_columns() {
        let columns = vec![
            test_column("id", "int"),
            db::ColumnInfo { extra: Some("DEFAULT_GENERATED".to_string()), ..test_column("created_at", "timestamp") },
            db::ColumnInfo { extra: Some("auto_increment".to_string()), ..test_column("sequence_id", "bigint") },
            db::ColumnInfo {
                extra: Some("VIRTUAL GENERATED".to_string()),
                ..test_column("virtual_total", "decimal(10,2)")
            },
            db::ColumnInfo { extra: Some("stored generated".to_string()), ..test_column("stored_hash", "varchar(64)") },
            db::ColumnInfo {
                extra: Some("PERSISTENT GENERATED".to_string()),
                ..test_column("persistent_total", "decimal(10,2)")
            },
            db::ColumnInfo { extra: Some("GENERATED ALWAYS".to_string()), ..test_column("explicit_generated", "int") },
            db::ColumnInfo {
                extra: Some("on update CURRENT_TIMESTAMP".to_string()),
                ..test_column("updated_at", "timestamp")
            },
        ];

        let writable = writable_transfer_columns(&columns, &DatabaseType::Mysql, &DatabaseType::Mysql);

        assert_eq!(
            writable.iter().map(|column| column.name.as_str()).collect::<Vec<_>>(),
            vec!["id", "created_at", "sequence_id", "updated_at"]
        );
        assert_eq!(columns.len(), 8, "DDL metadata must retain generated columns");
    }

    #[test]
    fn non_mysql_transfer_columns_keep_generated_markers() {
        let columns = vec![
            test_column("id", "int"),
            db::ColumnInfo { extra: Some("STORED GENERATED".to_string()), ..test_column("computed", "int") },
        ];

        let writable = writable_transfer_columns(&columns, &DatabaseType::Postgres, &DatabaseType::Postgres);

        assert_eq!(writable.iter().map(|column| column.name.as_str()).collect::<Vec<_>>(), vec!["id", "computed"]);
    }

    #[test]
    fn non_sqlserver_target_writable_transfer_columns_keep_timestamp_type() {
        let columns = vec![test_column("id", "int"), test_column("updated_at", "timestamp")];

        let writable = writable_transfer_columns(&columns, &DatabaseType::Postgres, &DatabaseType::Postgres);
        assert_eq!(writable.iter().map(|column| column.name.as_str()).collect::<Vec<_>>(), vec!["id", "updated_at"]);
    }

    #[test]
    fn sqlserver_target_keeps_timestamp_from_other_source_databases() {
        let columns = vec![test_column("id", "int"), test_column("updated_at", "timestamp")];

        let writable = writable_transfer_columns(&columns, &DatabaseType::Postgres, &DatabaseType::SqlServer);

        assert_eq!(writable.iter().map(|column| column.name.as_str()).collect::<Vec<_>>(), vec!["id", "updated_at"]);
    }

    #[test]
    fn dameng_identity_insert_wrapper_quotes_schema_and_table() {
        let sql = wrap_dameng_identity_insert_sql(
            "INSERT INTO \"SYSDBA\".\"USERS\" (\"ID\") VALUES\n(1);",
            "USERS",
            "SYSDBA",
        );

        assert_eq!(
            sql,
            "SET IDENTITY_INSERT \"SYSDBA\".\"USERS\" ON;\nINSERT INTO \"SYSDBA\".\"USERS\" (\"ID\") VALUES\n(1);\nSET IDENTITY_INSERT \"SYSDBA\".\"USERS\" OFF;"
        );
    }

    #[test]
    fn mysql_create_table_includes_column_comments() {
        let cols = vec![
            db::ColumnInfo { comment: Some("用户ID".to_string()), is_primary_key: true, ..test_column("id", "int") },
            db::ColumnInfo {
                comment: Some("用户姓名".to_string()),
                is_nullable: false,
                ..test_column("name", "VARCHAR(100)")
            },
            db::ColumnInfo { comment: None, ..test_column("age", "int") },
        ];

        let ddl =
            generate_create_table_ddl(&cols, "users", "", "", &DatabaseType::Mysql, &DatabaseType::Mysql, None, None);

        assert!(ddl.contains("COMMENT '用户ID'"));
        assert!(ddl.contains("COMMENT '用户姓名'"));
        assert!(!ddl.contains("`age` INT COMMENT")); // no comment for age
        assert!(ddl.contains("`name` VARCHAR(100) NOT NULL COMMENT '用户姓名'"));
        assert!(ddl.contains("PRIMARY KEY (`id`)"));
    }

    #[test]
    fn dameng_create_table_omits_if_not_exists_without_changing_other_prefixes() {
        let cols = vec![test_column("id", "int")];

        let dameng = generate_create_table_ddl(
            &cols,
            "users",
            "source",
            "SYSDBA",
            &DatabaseType::Dameng,
            &DatabaseType::Mysql,
            None,
            None,
        );
        let mysql = generate_create_table_ddl(
            &cols,
            "users",
            "",
            "app",
            &DatabaseType::Mysql,
            &DatabaseType::Mysql,
            None,
            None,
        );
        let postgres = generate_create_table_ddl(
            &cols,
            "users",
            "",
            "public",
            &DatabaseType::Postgres,
            &DatabaseType::Mysql,
            None,
            None,
        );
        let sqlserver = generate_create_table_ddl(
            &cols,
            "users",
            "",
            "dbo",
            &DatabaseType::SqlServer,
            &DatabaseType::Mysql,
            None,
            None,
        );

        assert!(dameng.starts_with("CREATE TABLE \"SYSDBA\".\"users\" ("), "ddl: {dameng}");
        assert!(!dameng.contains("IF NOT EXISTS"), "ddl: {dameng}");
        assert!(dameng.contains("\"id\" INTEGER"), "ddl: {dameng}");
        assert!(mysql.starts_with("CREATE TABLE IF NOT EXISTS `users` ("), "ddl: {mysql}");
        assert!(postgres.starts_with("CREATE TABLE IF NOT EXISTS \"public\".\"users\" ("), "ddl: {postgres}");
        assert!(
            sqlserver.starts_with(
                "IF NOT EXISTS (SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = 'users')\nCREATE TABLE [dbo].[users] ("
            ),
            "ddl: {sqlserver}"
        );
    }

    #[test]
    fn postgres_create_table_preserves_defaults_identity_and_exact_types() {
        let cols = vec![
            db::ColumnInfo {
                data_type: "integer".to_string(),
                column_default: Some("nextval('public.users_id_seq'::regclass)".to_string()),
                is_primary_key: true,
                is_nullable: false,
                ..test_column("id", "integer")
            },
            db::ColumnInfo {
                data_type: "timestamp with time zone".to_string(),
                column_default: Some("now()".to_string()),
                is_nullable: false,
                ..test_column("created_at", "timestamp with time zone")
            },
            db::ColumnInfo {
                data_type: "character varying(120)".to_string(),
                column_default: Some("'guest'::character varying".to_string()),
                ..test_column("name", "character varying(120)")
            },
        ];

        let ddl = generate_create_table_ddl(
            &cols,
            "users",
            "public",
            "public",
            &DatabaseType::Postgres,
            &DatabaseType::Postgres,
            None,
            None,
        );

        assert!(ddl.contains("\"id\" integer GENERATED BY DEFAULT AS IDENTITY NOT NULL"));
        assert!(ddl.contains("\"created_at\" timestamp with time zone DEFAULT now() NOT NULL"));
        assert!(ddl.contains("\"name\" character varying(120) DEFAULT 'guest'::character varying"));
        assert!(ddl.contains("PRIMARY KEY (\"id\")"));
    }

    #[test]
    fn postgres_create_table_rewrites_schema_qualified_custom_types_and_defaults() {
        let cols = vec![db::ColumnInfo {
            data_type: "\"public\".\"user_status\"".to_string(),
            column_default: Some("'active'::public.user_status".to_string()),
            is_nullable: false,
            ..test_column("status", "\"public\".\"user_status\"")
        }];

        let ddl = generate_create_table_ddl(
            &cols,
            "users",
            "public",
            "archive",
            &DatabaseType::Postgres,
            &DatabaseType::Postgres,
            None,
            None,
        );

        assert!(
            ddl.contains("\"status\" \"archive\".\"user_status\" DEFAULT 'active'::\"archive\".user_status NOT NULL")
        );
    }

    #[test]
    fn mysql_create_table_includes_table_comment() {
        let cols = vec![db::ColumnInfo { is_primary_key: true, ..test_column("id", "int") }];

        let ddl = generate_create_table_ddl(
            &cols,
            "users",
            "",
            "",
            &DatabaseType::Mysql,
            &DatabaseType::Mysql,
            Some("用户表"),
            None,
        );

        assert!(ddl.contains(") COMMENT='用户表'"));
    }

    #[test]
    fn mysql_text_pk_gets_key_prefix() {
        let cols =
            vec![db::ColumnInfo { data_type: "text".to_string(), is_primary_key: true, ..test_column("id", "text") }];

        let ddl =
            generate_create_table_ddl(&cols, "logs", "", "", &DatabaseType::Mysql, &DatabaseType::Sqlite, None, None);

        assert!(ddl.contains("PRIMARY KEY (`id`(255))"));
        assert!(ddl.contains("`id` TEXT"));
    }

    #[test]
    fn mysql_int_pk_no_prefix() {
        let cols = vec![db::ColumnInfo { is_primary_key: true, ..test_column("id", "int") }];

        let ddl =
            generate_create_table_ddl(&cols, "users", "", "", &DatabaseType::Mysql, &DatabaseType::Sqlite, None, None);

        assert!(ddl.contains("PRIMARY KEY (`id`)"));
        assert!(!ddl.contains("PRIMARY KEY (`id`(255))"));
    }

    #[test]
    fn postgres_comment_ddl_generates_column_and_table_comments() {
        let cols = vec![
            db::ColumnInfo { comment: Some("主键".to_string()), ..test_column("id", "int") },
            db::ColumnInfo { comment: Some("名称".to_string()), ..test_column("name", "varchar(100)") },
        ];

        let stmts = generate_comment_ddl(&cols, "items", "public", &DatabaseType::Postgres, Some("项目表"));

        assert_eq!(stmts.len(), 3);
        assert!(stmts[0].contains("COMMENT ON TABLE \"public\".\"items\" IS '项目表'"));
        assert!(stmts[1].contains("COMMENT ON COLUMN \"public\".\"items\".\"id\" IS '主键'"));
        assert!(stmts[2].contains("COMMENT ON COLUMN \"public\".\"items\".\"name\" IS '名称'"));
    }

    #[test]
    fn kingbase_comment_ddl_generates_and_escapes_comments() {
        let cols = vec![
            db::ColumnInfo { comment: Some("owner's id".to_string()), ..test_column("id", "int") },
            db::ColumnInfo { comment: Some("display name".to_string()), ..test_column("name", "varchar(100)") },
        ];

        let stmts = generate_comment_ddl(&cols, "items", "public", &DatabaseType::Kingbase, Some("team's items"));

        assert_eq!(
            stmts,
            vec![
                "COMMENT ON TABLE \"public\".\"items\" IS 'team''s items'".to_string(),
                "COMMENT ON COLUMN \"public\".\"items\".\"id\" IS 'owner''s id'".to_string(),
                "COMMENT ON COLUMN \"public\".\"items\".\"name\" IS 'display name'".to_string(),
            ]
        );
    }

    #[test]
    fn kingbase_comment_ddl_skips_empty_comments() {
        let cols = vec![
            db::ColumnInfo { comment: None, ..test_column("id", "int") },
            db::ColumnInfo { comment: Some("  ".to_string()), ..test_column("name", "varchar(100)") },
        ];

        let stmts = generate_comment_ddl(&cols, "items", "public", &DatabaseType::Kingbase, Some("  "));

        assert!(stmts.is_empty());
    }

    #[test]
    fn postgres_transfer_ddl_splits_reused_multi_statement_table_ddl() {
        let ddl =
            "CREATE TABLE \"public\".\"items\" (\"id\" integer);\nCOMMENT ON TABLE \"public\".\"items\" IS 'items';";

        let statements = transfer_ddl_statements(ddl, &DatabaseType::Postgres);

        assert_eq!(
            statements,
            vec![
                "CREATE TABLE \"public\".\"items\" (\"id\" integer)".to_string(),
                "COMMENT ON TABLE \"public\".\"items\" IS 'items'".to_string(),
            ]
        );
    }

    #[test]
    fn dameng_transfer_ddl_splits_reused_table_comments() {
        let ddl = "CREATE TABLE \"APP\".\"ITEMS\" (\n\
                     \"ID\" INTEGER,\n\
                     \"NOTE\" VARCHAR(100)\n\
                   );\n\
                   COMMENT ON TABLE \"APP\".\"ITEMS\" IS 'owner''s; items';\n\
                   COMMENT ON COLUMN \"APP\".\"ITEMS\".\"NOTE\" IS 'line; two';";

        let statements = transfer_ddl_statements(ddl, &DatabaseType::Dameng);

        assert_eq!(
            statements,
            vec![
                "CREATE TABLE \"APP\".\"ITEMS\" (\n\
                   \"ID\" INTEGER,\n\
                   \"NOTE\" VARCHAR(100)\n\
                 )"
                .to_string(),
                "COMMENT ON TABLE \"APP\".\"ITEMS\" IS 'owner''s; items'".to_string(),
                "COMMENT ON COLUMN \"APP\".\"ITEMS\".\"NOTE\" IS 'line; two'".to_string(),
            ]
        );
    }

    #[test]
    fn dameng_transfer_ddl_preserves_plsql_blocks_and_single_statements() {
        let script = "BEGIN\n\
                        EXECUTE IMMEDIATE 'CREATE TABLE \"APP\".\"AUDIT\" (\"ID\" INTEGER)';\n\
                      END;\n\
                      /\n\
                      COMMENT ON TABLE \"APP\".\"AUDIT\" IS 'audit';";

        let statements = transfer_ddl_statements(script, &DatabaseType::Dameng);

        assert_eq!(statements.len(), 2);
        assert!(statements[0].starts_with("BEGIN\n"));
        assert!(statements[0].contains("EXECUTE IMMEDIATE 'CREATE TABLE"));
        assert!(statements[0].ends_with("END;"));
        assert_eq!(statements[1], "COMMENT ON TABLE \"APP\".\"AUDIT\" IS 'audit'");

        let single = "CREATE TABLE \"APP\".\"SINGLE_ITEM\" (\"ID\" INTEGER)";
        assert_eq!(transfer_ddl_statements(single, &DatabaseType::Dameng), vec![single.to_string()]);
    }

    #[test]
    fn postgres_transfer_ddl_skips_reused_index_statements() {
        let ddl = "CREATE TABLE \"public\".\"items\" (\"id\" integer);\n\
                   CREATE INDEX \"items_lower_idx\" ON \"public\".\"items\" USING btree (\"lower(name)\");\n\
                   COMMENT ON INDEX \"public\".\"items_lower_idx\" IS 'lookup';";

        let statements = transfer_ddl_statements(ddl, &DatabaseType::Postgres);

        assert_eq!(statements, vec!["CREATE TABLE \"public\".\"items\" (\"id\" integer)".to_string()]);
    }

    #[test]
    fn postgres_transfer_ddl_removes_inline_foreign_keys_from_reused_table_ddl() {
        let ddl = "CREATE TABLE \"public\".\"audit_logs\" (\n  \"id\" integer,\n  \"user_id\" integer,\n  CONSTRAINT \"audit_logs_user_id_fkey\" FOREIGN KEY (\"user_id\") REFERENCES \"users\"(\"id\")\n);";

        let statements = transfer_ddl_statements(ddl, &DatabaseType::Postgres);

        assert_eq!(
            statements,
            vec!["CREATE TABLE \"public\".\"audit_logs\" (\n  \"id\" integer,\n  \"user_id\" integer\n)".to_string()]
        );
    }

    #[test]
    fn transfer_create_table_result_treats_existing_table_as_preexisting() {
        assert!(!transfer_create_table_created(
            Err("ERROR: relation \"items\" already exists (SQLSTATE 42P07)".to_string()),
            "create"
        )
        .unwrap());
        assert!(!transfer_create_table_created(Err("错误: 关系 \"items\" 已经存在".to_string()), "create").unwrap());
        assert!(transfer_create_table_created(Ok(()), "create").unwrap());
        assert_eq!(
            transfer_create_table_created(Err("permission denied for schema public".to_string()), "create")
                .unwrap_err(),
            "create: permission denied for schema public"
        );
    }

    #[test]
    fn non_postgres_transfer_ddl_keeps_statement_text_intact() {
        let ddl = "CREATE TABLE `items` (`id` int);\nALTER TABLE `items` COMMENT = 'items';";

        assert_eq!(transfer_ddl_statements(ddl, &DatabaseType::Mysql), vec![ddl.to_string()]);
    }

    #[test]
    fn clickhouse_comment_ddl_uses_alter_table() {
        let cols = vec![db::ColumnInfo { comment: Some("日志消息".to_string()), ..test_column("message", "text") }];

        let stmts = generate_comment_ddl(&cols, "logs", "", &DatabaseType::ClickHouse, None);

        assert_eq!(stmts.len(), 1);
        assert!(stmts[0].contains("ALTER TABLE `logs` COMMENT COLUMN `message` '日志消息'"));
    }

    #[test]
    fn pg_comment_ddl_skips_empty_comments() {
        let cols = vec![
            db::ColumnInfo { comment: None, ..test_column("id", "int") },
            db::ColumnInfo { comment: Some("  ".to_string()), ..test_column("name", "varchar(100)") },
        ];

        let stmts = generate_comment_ddl(&cols, "t", "", &DatabaseType::Postgres, None);

        assert!(stmts.is_empty());
    }

    #[test]
    fn non_mysql_family_no_inline_comment() {
        let cols = vec![db::ColumnInfo { comment: Some("test".to_string()), ..test_column("col", "text") }];

        // PostgreSQL target should NOT have inline COMMENT
        let ddl =
            generate_create_table_ddl(&cols, "t", "", "", &DatabaseType::Postgres, &DatabaseType::Postgres, None, None);
        assert!(!ddl.contains("COMMENT"));
    }

    #[test]
    fn clickhouse_create_table_with_pk_uses_order_by_pk() {
        let cols = vec![
            db::ColumnInfo { is_primary_key: true, is_nullable: false, ..test_column("id", "UInt64") },
            db::ColumnInfo { ..test_column("name", "String") },
        ];

        let ddl = generate_create_table_ddl(
            &cols,
            "logs",
            "",
            "",
            &DatabaseType::ClickHouse,
            &DatabaseType::ClickHouse,
            None,
            None,
        );

        // Must include ENGINE with ORDER BY using the PK columns
        assert!(ddl.contains("ENGINE = MergeTree() ORDER BY (`id`)"));
        // Must NOT have a separate PRIMARY KEY clause (ORDER BY serves that role)
        assert!(!ddl.contains("PRIMARY KEY"));
    }

    #[test]
    fn clickhouse_create_table_without_pk_uses_order_by_tuple() {
        let cols = vec![db::ColumnInfo { ..test_column("message", "String") }];

        let ddl = generate_create_table_ddl(
            &cols,
            "logs",
            "",
            "",
            &DatabaseType::ClickHouse,
            &DatabaseType::ClickHouse,
            None,
            None,
        );

        assert!(ddl.contains("ENGINE = MergeTree() ORDER BY tuple()"));
        assert!(!ddl.contains("PRIMARY KEY"));
    }

    #[test]
    fn clickhouse_transfer_maps_fractional_timestamp_to_datetime64() {
        let cols = vec![db::ColumnInfo { numeric_scale: Some(6), ..test_column("created_at", "TIMESTAMP") }];

        let ddl = generate_create_table_ddl(
            &cols,
            "events",
            "SYSDBA",
            "",
            &DatabaseType::ClickHouse,
            &DatabaseType::Dameng,
            None,
            None,
        );

        assert!(ddl.contains("`created_at` DateTime64(6)"), "ddl: {ddl}");
    }

    #[test]
    fn clickhouse_transfer_uses_datetime64_fallback_for_timestamp_types() {
        assert_eq!(map_column_type("datetime", &DatabaseType::Dameng, &DatabaseType::ClickHouse), "DateTime64(6)");
        assert_eq!(map_column_type("timestamp", &DatabaseType::Dameng, &DatabaseType::ClickHouse), "DateTime64(6)");
    }

    #[test]
    fn transfer_reuses_source_table_ddl_only_when_target_shape_matches() {
        assert!(!can_reuse_source_table_ddl(&DatabaseType::ClickHouse, &DatabaseType::ClickHouse, None, None, true,));
        assert!(can_reuse_source_table_ddl(&DatabaseType::Postgres, &DatabaseType::Postgres, None, None, true,));
        assert!(!can_reuse_source_table_ddl(&DatabaseType::Postgres, &DatabaseType::Postgres, None, None, false,));
    }

    #[test]
    fn oceanbase_mysql_transfer_only_reuses_ddl_for_an_oceanbase_target() {
        assert!(
            !can_reuse_source_table_ddl(&DatabaseType::Mysql, &DatabaseType::Mysql, Some("oceanbase"), None, true,)
        );
        assert!(can_reuse_source_table_ddl(
            &DatabaseType::Mysql,
            &DatabaseType::Mysql,
            Some("OceanBase"),
            Some("oceanbase"),
            true,
        ));
        assert!(can_reuse_source_table_ddl(&DatabaseType::Mysql, &DatabaseType::Mysql, None, None, true,));
    }

    #[test]
    fn mysql_transfer_collation_recovery_only_reads_ddl_code() {
        let ddl = r#"CREATE TABLE `COLLATE utf8mb4_identifier_ci` (
  `id` bigint NOT NULL,
  `note` varchar(255) COMMENT 'COLLATE utf8mb4_literal_ci',
  `name` varchar(64) COLLATE utf8mb4_0900_ai_ci,
  `legacy` varchar(64) collate = utf8mb4_unicode_ci
) DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
/* COLLATE utf8mb4_comment_ci */"#;

        assert_eq!(
            mysql_ddl_collation_names(ddl),
            vec!["utf8mb4_0900_ai_ci".to_string(), "utf8mb4_unicode_ci".to_string()]
        );
    }

    #[test]
    fn mysql_transfer_collation_recovery_removes_only_unsupported_clauses() {
        let ddl = r#"CREATE TABLE `items` (
  `name` varchar(64) COLLATE utf8mb4_0900_ai_ci COMMENT 'COLLATE utf8mb4_0900_ai_ci',
  `legacy` varchar(64) COLLATE utf8mb4_unicode_ci
) DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci COMMENT='items'"#;
        let supported = HashSet::from(["utf8mb4_unicode_ci".to_string()]);

        let rewritten = remove_unsupported_mysql_collations(ddl, &supported);

        assert!(!rewritten.contains("varchar(64) COLLATE utf8mb4_0900_ai_ci"));
        assert!(!rewritten.contains("utf8mb4 COLLATE=utf8mb4_0900_ai_ci"));
        assert!(rewritten.contains("COLLATE utf8mb4_unicode_ci"));
        assert!(rewritten.contains("COMMENT 'COLLATE utf8mb4_0900_ai_ci'"));
        assert!(rewritten.contains("DEFAULT CHARSET=utf8mb4"));
        assert!(rewritten.contains("COMMENT='items'"));
    }

    #[test]
    fn mysql_transfer_collation_recovery_has_a_narrow_error_gate() {
        let ddl = "CREATE TABLE `items` (`name` varchar(64) COLLATE utf8mb4_0900_ai_ci)";

        assert_eq!(
            mysql_collations_for_transfer_ddl_recovery(
                ddl,
                "ERROR 1273 (HY000): Unknown collation: 'utf8mb4_0900_ai_ci'",
                &DatabaseType::Mysql,
                true,
            ),
            Some(vec!["utf8mb4_0900_ai_ci".to_string()])
        );
        assert_eq!(
            mysql_collations_for_transfer_ddl_recovery(
                ddl,
                "ERROR 1064 (42000): syntax error",
                &DatabaseType::Mysql,
                true,
            ),
            None
        );
        assert_eq!(
            mysql_collations_for_transfer_ddl_recovery(
                ddl,
                "ERROR 1273 (HY000): Unknown collation",
                &DatabaseType::Mysql,
                false,
            ),
            None
        );
        assert_eq!(
            mysql_collations_for_transfer_ddl_recovery(
                ddl,
                "ERROR 1273 (HY000): Unknown collation",
                &DatabaseType::Postgres,
                true,
            ),
            None
        );
    }

    #[test]
    fn detects_oceanbase_mysql_table_options_outside_literals_and_comments() {
        let ddl = r#"CREATE TABLE `items` (
  `id` bigint NOT NULL AUTO_INCREMENT,
  KEY `idx_name` (`name`) BLOCK_SIZE 16384 LOCAL
) AUTO_INCREMENT = 42 AUTO_INCREMENT_MODE = 'ORDER'
  DEFAULT CHARSET = utf8mb4 REPLICA_NUM = 1 USE_BLOOM_FILTER = FALSE
  TABLET_SIZE = 134217728 PCTFREE = 0"#;
        assert!(contains_oceanbase_mysql_table_options(ddl));

        let portable = r#"CREATE TABLE `items` (
  `id` bigint NOT NULL AUTO_INCREMENT,
  `note` varchar(255) COMMENT 'AUTO_INCREMENT_MODE and PCTFREE',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='USE_BLOOM_FILTER'"#;
        assert!(!contains_oceanbase_mysql_table_options(portable));
    }

    #[test]
    fn postgres_transfer_reused_table_ddl_rewrites_target_schema() {
        let ddl =
            "CREATE TABLE \"src\".\"items\" (\"id\" integer);\nCOMMENT ON COLUMN \"src\".\"items\".\"id\" IS 'id';";

        let rewritten =
            rewrite_transfer_source_table_ddl(ddl, "src", "dst", &DatabaseType::Postgres, &DatabaseType::Postgres);

        assert!(rewritten.contains("CREATE TABLE \"dst\".\"items\""));
        assert!(rewritten.contains("COMMENT ON COLUMN \"dst\".\"items\".\"id\""));
        assert!(!rewritten.contains("\"src\".\"items\""));
    }

    #[test]
    fn hive_create_table_uses_hive_friendly_columns() {
        let cols = vec![
            db::ColumnInfo { is_primary_key: true, is_nullable: false, ..test_column("id", "bigint") },
            db::ColumnInfo { is_nullable: false, ..test_column("payload", "json") },
        ];

        let ddl = generate_create_table_ddl(
            &cols,
            "events",
            "public",
            "warehouse",
            &DatabaseType::Hive,
            &DatabaseType::Postgres,
            None,
            None,
        );

        assert!(ddl.contains("CREATE TABLE IF NOT EXISTS `warehouse`.`events`"));
        assert!(ddl.contains("`id` BIGINT"));
        assert!(ddl.contains("`payload` STRING"));
        assert!(!ddl.contains("PRIMARY KEY"));
        assert!(!ddl.contains("NOT NULL"));
    }

    #[test]
    fn hive_transfer_uses_backticks_and_hive_type_mapping() {
        assert_eq!(quote_identifier("user`events", &DatabaseType::Hive), "`user``events`");
        assert_eq!(map_column_type("jsonb", &DatabaseType::Postgres, &DatabaseType::Hive), "STRING");
        assert_eq!(
            map_column_type("timestamp with time zone", &DatabaseType::Postgres, &DatabaseType::Hive),
            "TIMESTAMP"
        );
    }

    #[test]
    fn mongo_transfer_document_fields_preserve_first_seen_order() {
        let documents = vec![json!({"b": 1}), json!({"a": 2, "c": 3}), json!({"b": 4, "d": 5})];

        assert_eq!(mongo_transfer_document_fields(&documents), vec!["b", "a", "c", "d"]);
    }

    #[test]
    fn mongo_transfer_rows_fill_missing_fields_with_null() {
        let rows = mongo_documents_to_rows(
            &[json!({"id": 1, "name": "Ada"}), json!({"id": 2})],
            &[String::from("id"), String::from("name")],
        );

        assert_eq!(rows, vec![vec![json!(1), json!("Ada")], vec![json!(2), serde_json::Value::Null]]);
    }

    #[test]
    fn sql_rows_to_mongo_documents_maps_columns_to_fields() {
        let documents = sql_rows_to_mongo_documents(
            &[String::from("id"), String::from("name"), String::from("active")],
            &[vec![json!(1), json!("Ada")], vec![json!(2), json!("Grace"), json!(true)]],
        );

        assert_eq!(
            documents,
            vec![json!({"id": 1, "name": "Ada", "active": null}), json!({"id": 2, "name": "Grace", "active": true})]
        );
    }

    #[test]
    fn postgres_pagination_uses_stable_primary_key_order() {
        let sql = pagination_sql_with_order(
            &[String::from("id"), String::from("name")],
            "users",
            "public",
            &DatabaseType::Postgres,
            200,
            100,
            &[String::from("id")],
            None,
        );

        assert_eq!(sql, "SELECT \"id\", \"name\" FROM \"public\".\"users\" ORDER BY \"id\" LIMIT 100 OFFSET 200");
    }

    #[test]
    fn doris_unique_key_columns_drive_transfer_pagination_order() {
        let columns =
            vec![db::ColumnInfo { is_unique: true, ..test_column("id", "int") }, test_column("payload", "varchar(64)")];
        let key_columns = transfer_key_columns(&columns, &DatabaseType::Doris);

        assert_eq!(key_columns, vec![String::from("id")]);
        assert_eq!(
            pagination_sql_with_order(
                &[String::from("id"), String::from("payload")],
                "events",
                "analytics",
                &DatabaseType::Doris,
                1000,
                1000,
                &key_columns,
                None,
            ),
            "SELECT `id`, `payload` FROM `analytics`.`events` ORDER BY `id` LIMIT 1000 OFFSET 1000"
        );
    }

    #[test]
    fn mysql_unique_columns_do_not_become_transfer_keys() {
        let columns = vec![db::ColumnInfo { is_unique: true, ..test_column("email", "varchar(255)") }];

        assert!(transfer_key_columns(&columns, &DatabaseType::Mysql).is_empty());
    }

    #[test]
    fn questdb_pagination_uses_stable_primary_key_order() {
        let sql = pagination_sql_with_order(
            &[String::from("id"), String::from("name")],
            "users",
            "public",
            &DatabaseType::Questdb,
            200,
            100,
            &[String::from("id")],
            None,
        );

        assert_eq!(sql, "SELECT `id`, `name` FROM `users` ORDER BY `id` LIMIT 200, 300");
    }

    #[test]
    fn dameng_export_pagination_uses_offset_fetch() {
        let sql = pagination_sql(
            &[String::from("id"), String::from("name")],
            "users",
            "SYSDBA",
            &DatabaseType::Dameng,
            500,
            100,
        );

        assert_eq!(
            sql,
            "SELECT \"id\", \"name\" FROM \"SYSDBA\".\"users\" ORDER BY (SELECT NULL) OFFSET 500 ROWS FETCH NEXT 100 ROWS ONLY"
        );
        assert!(!sql.contains(" LIMIT "));
    }

    #[test]
    fn dameng_ordered_pagination_uses_offset_fetch() {
        let sql = pagination_sql_with_order(
            &[String::from("id"), String::from("name")],
            "users",
            "SYSDBA",
            &DatabaseType::Dameng,
            200,
            100,
            &[String::from("id")],
            None,
        );

        assert_eq!(
            sql,
            "SELECT \"id\", \"name\" FROM \"SYSDBA\".\"users\" ORDER BY \"id\" OFFSET 200 ROWS FETCH NEXT 100 ROWS ONLY"
        );
        assert!(!sql.contains(" LIMIT "));
    }

    #[test]
    fn filtered_pagination_preserves_where_and_order() {
        let sql = pagination_sql_with_filter_order(
            &[String::from("id"), String::from("status")],
            "users",
            "public",
            &DatabaseType::SapHana,
            10_000,
            2_000,
            Some("WHERE status = 'active'"),
            Some("\"id\" DESC"),
            &[String::from("id")],
        );

        assert_eq!(
            sql,
            "SELECT \"id\", \"status\" FROM \"public\".\"users\" WHERE (status = 'active') ORDER BY \"id\" DESC LIMIT 2000 OFFSET 10000"
        );
    }

    #[test]
    fn dameng_filtered_pagination_preserves_where_and_order() {
        let sql = pagination_sql_with_filter_order(
            &[String::from("id"), String::from("status")],
            "users",
            "SYSDBA",
            &DatabaseType::Dameng,
            10_000,
            2_000,
            Some("WHERE status = 'active'"),
            Some("\"id\" DESC"),
            &[String::from("id")],
        );

        assert_eq!(
            sql,
            "SELECT \"id\", \"status\" FROM \"SYSDBA\".\"users\" WHERE (status = 'active') ORDER BY \"id\" DESC OFFSET 10000 ROWS FETCH NEXT 2000 ROWS ONLY"
        );
        assert!(!sql.contains(" LIMIT "));
    }

    #[test]
    fn oracle_filtered_pagination_uses_rownum_for_legacy_compatibility() {
        let sql = pagination_sql_with_filter_order(
            &[String::from("id"), String::from("status")],
            "users",
            "APP",
            &DatabaseType::Oracle,
            10_000,
            2_000,
            Some("WHERE status = 'active'"),
            Some("\"id\" DESC"),
            &[String::from("id")],
        );

        assert_eq!(
            sql,
            "SELECT \"id\", \"status\" FROM (SELECT dbx_inner.*, ROWNUM AS \"__dbx_row_num\" FROM (SELECT \"id\", \"status\" FROM \"APP\".\"users\" WHERE (status = 'active') ORDER BY \"id\" DESC) dbx_inner WHERE ROWNUM <= 12000) WHERE \"__dbx_row_num\" > 10000"
        );
        assert!(!sql.contains("OFFSET"));
        assert!(!sql.contains("FETCH NEXT"));
    }

    #[test]
    fn filtered_count_preserves_where() {
        let sql =
            count_sql_with_where("users", "public", &DatabaseType::SapHana, Some("WHERE status = 'active'"), None);

        assert_eq!(sql, "SELECT COUNT(*) FROM \"public\".\"users\" WHERE (status = 'active')");
    }

    #[test]
    fn sqlserver_keyset_pagination_includes_offset_fetch() {
        let sql = keyset_pagination_sql(
            &[String::from("id"), String::from("name")],
            "users",
            "dbo",
            &DatabaseType::SqlServer,
            &[String::from("id")],
            &[],
            100,
        );

        assert_eq!(
            sql,
            "SELECT [id], [name] FROM [dbo].[users] ORDER BY [id] ASC OFFSET 0 ROWS FETCH NEXT 100 ROWS ONLY"
        );
    }

    #[test]
    fn dameng_keyset_pagination_includes_offset_fetch() {
        let sql = keyset_pagination_sql(
            &[String::from("id"), String::from("name")],
            "users",
            "SYSDBA",
            &DatabaseType::Dameng,
            &[String::from("id")],
            &[json!(25)],
            100,
        );

        assert_eq!(
            sql,
            "SELECT \"id\", \"name\" FROM \"SYSDBA\".\"users\" WHERE \"id\" > 25 ORDER BY \"id\" ASC OFFSET 0 ROWS FETCH NEXT 100 ROWS ONLY"
        );
        assert!(!sql.contains(" LIMIT "));
    }

    #[test]
    fn oracle_keyset_pagination_uses_rownum_for_legacy_compatibility() {
        let sql = keyset_pagination_sql(
            &[String::from("id"), String::from("name")],
            "users",
            "APP",
            &DatabaseType::Oracle,
            &[String::from("id")],
            &[json!(25)],
            100,
        );

        assert_eq!(
            sql,
            "SELECT \"id\", \"name\" FROM (SELECT \"id\", \"name\" FROM \"APP\".\"users\" WHERE \"id\" > 25 ORDER BY \"id\" ASC) WHERE ROWNUM <= 100"
        );
        assert!(!sql.contains("OFFSET"));
        assert!(!sql.contains("FETCH NEXT"));
    }

    #[test]
    fn composite_keyset_pagination_uses_portable_lexicographic_predicate() {
        let sql = keyset_pagination_sql(
            &[String::from("tenant_id"), String::from("id"), String::from("name")],
            "users",
            "dbo",
            &DatabaseType::SqlServer,
            &[String::from("tenant_id"), String::from("id")],
            &[json!(10), json!(25)],
            100,
        );

        assert_eq!(
            sql,
            "SELECT [tenant_id], [id], [name] FROM [dbo].[users] WHERE ([tenant_id] > 10 OR ([tenant_id] = 10 AND [id] > 25)) ORDER BY [tenant_id] ASC, [id] ASC OFFSET 0 ROWS FETCH NEXT 100 ROWS ONLY"
        );
    }

    #[test]
    fn postgres_generates_index_and_foreign_key_sql() {
        let indexes = vec![db::IndexInfo {
            name: "users_name_idx".to_string(),
            columns: vec!["lower(name)".to_string()],
            is_unique: false,
            is_primary: false,
            filter: Some("name IS NOT NULL".to_string()),
            index_type: Some("btree".to_string()),
            included_columns: Some(vec!["created_at".to_string()]),
            comment: Some("lookup index".to_string()),
        }];
        let foreign_keys = vec![
            db::ForeignKeyInfo {
                name: "orders_user_id_fkey".to_string(),
                column: "user_id".to_string(),
                ref_schema: None,
                ref_table: "users".to_string(),
                ref_column: "id".to_string(),
                on_update: None,
                on_delete: None,
            },
            db::ForeignKeyInfo {
                name: "orders_user_id_fkey".to_string(),
                column: "tenant_id".to_string(),
                ref_schema: None,
                ref_table: "users".to_string(),
                ref_column: "tenant_id".to_string(),
                on_update: None,
                on_delete: None,
            },
        ];

        let index_sql = generate_postgres_index_ddl(&indexes, "users", "public");
        let foreign_key_sql = generate_postgres_foreign_key_ddl(&foreign_keys, "orders", "public", "archive");

        assert_eq!(
            index_sql,
            vec![
                "CREATE INDEX IF NOT EXISTS \"users_name_idx\" ON \"public\".\"users\" USING btree (lower(name)) INCLUDE (\"created_at\") WHERE name IS NOT NULL".to_string(),
                "COMMENT ON INDEX \"public\".\"users_name_idx\" IS 'lookup index'".to_string(),
            ]
        );
        assert_eq!(
            foreign_key_sql,
            vec![
                "ALTER TABLE \"archive\".\"orders\" ADD CONSTRAINT \"orders_user_id_fkey\" FOREIGN KEY (\"user_id\", \"tenant_id\") REFERENCES \"archive\".\"users\" (\"id\", \"tenant_id\")".to_string()
            ]
        );
    }

    #[test]
    fn postgres_sequence_sync_sql_uses_table_max_values() {
        let sql = generate_postgres_sequence_sync_sql(
            &[
                db::ColumnInfo {
                    name: "id".to_string(),
                    data_type: "integer".to_string(),
                    is_nullable: false,
                    column_default: Some("nextval('public.users_id_seq'::regclass)".to_string()),
                    is_primary_key: true,
                    extra: None,
                    comment: None,
                    numeric_precision: None,
                    numeric_scale: None,
                    character_maximum_length: None,
                    enum_values: None,
                    ..Default::default()
                },
                db::ColumnInfo {
                    name: "identity_id".to_string(),
                    data_type: "integer".to_string(),
                    is_nullable: false,
                    column_default: None,
                    is_primary_key: false,
                    extra: Some("generated by default as identity".to_string()),
                    comment: None,
                    numeric_precision: None,
                    numeric_scale: None,
                    character_maximum_length: None,
                    enum_values: None,
                    ..Default::default()
                },
                db::ColumnInfo {
                    name: "computed_id".to_string(),
                    data_type: "integer".to_string(),
                    is_nullable: false,
                    column_default: None,
                    is_primary_key: false,
                    extra: Some("generated always as (identity_id + 1) stored".to_string()),
                    comment: None,
                    numeric_precision: None,
                    numeric_scale: None,
                    character_maximum_length: None,
                    enum_values: None,
                    ..Default::default()
                },
            ],
            "users",
            "public",
        );

        assert_eq!(
            sql,
            vec![
                "SELECT setval(pg_get_serial_sequence('\"public\".\"users\"', 'id'), GREATEST(COALESCE(MAX(\"id\"), 0), 1), MAX(\"id\") IS NOT NULL) FROM \"public\".\"users\"".to_string(),
                "SELECT setval(pg_get_serial_sequence('\"public\".\"users\"', 'identity_id'), GREATEST(COALESCE(MAX(\"identity_id\"), 0), 1), MAX(\"identity_id\") IS NOT NULL) FROM \"public\".\"users\"".to_string()
            ]
        );
    }

    #[test]
    fn postgres_transfer_owned_sequence_ddl_uses_precreate_and_post_bind_steps() {
        let sequence = PostgresOwnedSequence {
            name: "it_quick_entry_id_seq".to_string(),
            owner_table: "it_quick_entry".to_string(),
            owner_column: "id".to_string(),
        };
        let create_sql =
            format!("CREATE SEQUENCE IF NOT EXISTS {}", postgres_sequence_qualified_name("public", &sequence.name));
        let owner_sql = format!(
            "ALTER SEQUENCE {} OWNED BY {}.{}",
            postgres_sequence_qualified_name("public", &sequence.name),
            qualified_table(&sequence.owner_table, "public", &DatabaseType::Postgres, None),
            quote_identifier(&sequence.owner_column, &DatabaseType::Postgres)
        );

        assert_eq!(create_sql, "CREATE SEQUENCE IF NOT EXISTS \"public\".\"it_quick_entry_id_seq\"".to_string());
        assert_eq!(
            owner_sql,
            "ALTER SEQUENCE \"public\".\"it_quick_entry_id_seq\" OWNED BY \"public\".\"it_quick_entry\".\"id\""
                .to_string()
        );
    }

    #[test]
    fn postgres_owned_sequence_state_detects_conflicting_existing_sequence() {
        let source = PostgresOwnedSequence {
            name: "it_quick_entry_id_seq".to_string(),
            owner_table: "it_quick_entry".to_string(),
            owner_column: "id".to_string(),
        };

        let conflicting = PostgresSequenceSnapshot {
            name: "it_quick_entry_id_seq".to_string(),
            owner_table: Some("other_table".to_string()),
            owner_column: Some("id".to_string()),
        };

        let error = validate_existing_postgres_sequence(&source, Some(&conflicting), "archive").unwrap_err();

        assert!(error.contains("\"archive\".\"it_quick_entry_id_seq\""));
        assert!(error.contains("already exists with incompatible ownership"));
    }

    #[test]
    fn postgres_transfer_reused_table_ddl_preserves_serial_sequence_dependencies() {
        let columns = vec![
            db::ColumnInfo {
                name: "id".to_string(),
                data_type: "integer".to_string(),
                is_nullable: false,
                column_default: Some("nextval('public.it_quick_entry_id_seq'::regclass)".to_string()),
                is_primary_key: true,
                extra: None,
                comment: None,
                numeric_precision: None,
                numeric_scale: None,
                character_maximum_length: None,
                enum_values: None,
                ..Default::default()
            },
            db::ColumnInfo {
                name: "name".to_string(),
                data_type: "text".to_string(),
                is_nullable: false,
                column_default: None,
                is_primary_key: false,
                extra: None,
                comment: None,
                numeric_precision: None,
                numeric_scale: None,
                character_maximum_length: None,
                enum_values: None,
                ..Default::default()
            },
        ];
        let source_ddl = crate::schema::render_postgres_table_ddl("public", "it_quick_entry", &columns, &[], &[], None);
        let rewritten = rewrite_transfer_source_table_ddl(
            &source_ddl,
            "public",
            "archive",
            &DatabaseType::Postgres,
            &DatabaseType::Postgres,
        );
        let sequence = PostgresOwnedSequence {
            name: "it_quick_entry_id_seq".to_string(),
            owner_table: "it_quick_entry".to_string(),
            owner_column: "id".to_string(),
        };
        let create_sql =
            format!("CREATE SEQUENCE IF NOT EXISTS {}", postgres_sequence_qualified_name("archive", &sequence.name));
        let owner_sql = format!(
            "ALTER SEQUENCE {} OWNED BY {}.{}",
            postgres_sequence_qualified_name("archive", &sequence.name),
            qualified_table(&sequence.owner_table, "archive", &DatabaseType::Postgres, None),
            quote_identifier(&sequence.owner_column, &DatabaseType::Postgres)
        );
        let sequence_sync_sql = generate_postgres_sequence_sync_sql(&columns, "it_quick_entry", "archive");

        assert!(source_ddl.starts_with("CREATE TABLE \"public\".\"it_quick_entry\""));
        assert!(!source_ddl.contains("CREATE SEQUENCE"));
        assert!(rewritten.contains("CREATE TABLE \"archive\".\"it_quick_entry\""));
        assert!(rewritten.contains("nextval('\"archive\".it_quick_entry_id_seq'::regclass)"));
        assert_eq!(create_sql, "CREATE SEQUENCE IF NOT EXISTS \"archive\".\"it_quick_entry_id_seq\"".to_string());
        assert_eq!(
            owner_sql,
            "ALTER SEQUENCE \"archive\".\"it_quick_entry_id_seq\" OWNED BY \"archive\".\"it_quick_entry\".\"id\""
                .to_string()
        );
        assert_eq!(
            sequence_sync_sql,
            vec![
                "SELECT setval(pg_get_serial_sequence('\"archive\".\"it_quick_entry\"', 'id'), GREATEST(COALESCE(MAX(\"id\"), 0), 1), MAX(\"id\") IS NOT NULL) FROM \"archive\".\"it_quick_entry\"".to_string()
            ]
        );
    }

    #[test]
    fn postgres_routine_schema_rewrite_targets_destination_schema() {
        let rewritten = rewrite_postgres_routine_schema(
            "CREATE OR REPLACE FUNCTION public.bump_counter(id integer)\nRETURNS integer\nLANGUAGE plpgsql\nAS $$ BEGIN INSERT INTO public.audit_logs(user_id) VALUES (id); RETURN id + 1; END; $$",
            "public",
            "archive",
        )
        .unwrap();

        assert!(rewritten.starts_with("CREATE OR REPLACE FUNCTION \"archive\".\"bump_counter\"("));
        assert!(rewritten.contains("INSERT INTO \"archive\".audit_logs"));
    }

    #[test]
    fn postgres_trigger_schema_rewrite_targets_destination_table() {
        let rewritten = rewrite_postgres_trigger_table_schema(
            "CREATE TRIGGER bump BEFORE INSERT ON public.users FOR EACH ROW EXECUTE FUNCTION public.bump_counter()",
            "public",
            "users",
            "archive",
        );

        assert!(rewritten.contains(" ON \"archive\".\"users\" "));
        assert!(rewritten.contains("EXECUTE FUNCTION \"archive\".bump_counter()"));
    }

    #[test]
    fn postgres_extension_enum_and_domain_ddl_is_repeatable() {
        let extension_sql = generate_postgres_extension_ddl(
            &PostgresExtensionSource { extension_name: "pgcrypto".to_string() },
            "archive",
        );
        let enum_sql = generate_postgres_enum_ddl(
            &PostgresEnumSource {
                type_name: "status".to_string(),
                labels: vec!["pending".to_string(), "done".to_string()],
            },
            "archive",
        );
        let domain_sql = generate_postgres_domain_ddl(
            &PostgresDomainSource {
                domain_name: "email".to_string(),
                base_type: "text".to_string(),
                default_value: Some("'unknown@example.com'::text".to_string()),
                not_null: true,
                checks: vec!["CHECK ((VALUE ~* '^[^@]+@[^@]+$'::text))".to_string()],
            },
            "archive",
        );

        assert_eq!(extension_sql, "CREATE EXTENSION IF NOT EXISTS \"pgcrypto\" WITH SCHEMA \"archive\"");
        assert!(enum_sql.contains("DO $$ BEGIN IF NOT EXISTS"));
        assert!(enum_sql.contains("CREATE TYPE \"archive\".\"status\" AS ENUM ('pending', 'done')"));
        assert!(domain_sql.contains("CREATE DOMAIN \"archive\".\"email\" AS text DEFAULT 'unknown@example.com'::text NOT NULL CHECK ((VALUE ~* '^[^@]+@[^@]+$'::text))"));
    }

    #[test]
    fn postgres_materialized_view_ddls_drop_and_recreate_in_target_schema() {
        let ddls = generate_postgres_materialized_view_ddls(
            &PostgresMaterializedViewSource {
                view_name: "active_users".to_string(),
                source: "SELECT id, name FROM public.users WHERE active".to_string(),
            },
            "archive",
        );

        assert_eq!(ddls.len(), 2);
        assert_eq!(ddls[0], "DROP MATERIALIZED VIEW IF EXISTS \"archive\".\"active_users\"");
        assert_eq!(
            ddls[1],
            "CREATE MATERIALIZED VIEW \"archive\".\"active_users\" AS\nSELECT id, name FROM public.users WHERE active;"
        );
    }

    #[test]
    fn mysql_insert_normalizes_rfc3339_datetime_strings() {
        let sql = generate_insert_typed(
            &[String::from("insurance_start_time")],
            &[Some(String::from("datetime"))],
            &[vec![json!("2026-05-12T00:00:00+00:00")]],
            "policies",
            "",
            &DatabaseType::Mysql,
            None,
        );

        assert_eq!(sql, "INSERT INTO `policies` (`insurance_start_time`) VALUES\n('2026-05-12 00:00:00')");
    }

    #[test]
    fn count_sql_uses_three_part_name_for_mysql_external_catalog() {
        let sql = count_sql("t1", "ads", &DatabaseType::Mysql, Some("hive_catalog"));
        assert_eq!(sql, "SELECT COUNT(*) FROM `hive_catalog`.`ads`.`t1`");
    }

    #[test]
    fn count_sql_uses_three_part_name_for_starrocks_external_catalog() {
        let sql = count_sql("t1", "ads", &DatabaseType::StarRocks, Some("paimon"));
        assert_eq!(sql, "SELECT COUNT(*) FROM `paimon`.`ads`.`t1`");
    }

    #[test]
    fn mysql_insert_uses_column_types_for_temporal_literals() {
        let sql = generate_insert_typed(
            &[String::from("dt"), String::from("raw_text"), String::from("d"), String::from("t")],
            &[
                Some(String::from("datetime")),
                Some(String::from("varchar(64)")),
                Some(String::from("date")),
                Some(String::from("time")),
            ],
            &[vec![
                json!("2026-05-12T00:00:00+00:00"),
                json!("2026-05-12T00:00:00+00:00"),
                json!("2026-05-12T00:00:00+00:00"),
                json!("2026-05-12T09:30:45+00:00"),
            ]],
            "policies",
            "",
            &DatabaseType::Mysql,
            None,
        );

        assert_eq!(
            sql,
            "INSERT INTO `policies` (`dt`, `raw_text`, `d`, `t`) VALUES\n('2026-05-12 00:00:00', '2026-05-12T00:00:00+00:00', '2026-05-12', '09:30:45')"
        );
    }

    #[test]
    fn oracle_insert_uses_date_literals_for_date_columns() {
        let sql = generate_insert_typed(
            &[String::from("id"), String::from("created_on"), String::from("created_at"), String::from("raw_text")],
            &[
                Some(String::from("NUMBER")),
                Some(String::from("DATE")),
                Some(String::from("TIMESTAMP(6)")),
                Some(String::from("VARCHAR2(64)")),
            ],
            &[vec![
                json!(1),
                json!("2022-08-25T09:58:43Z"),
                json!("2022-08-25T09:58:43Z"),
                json!("2022-08-25T09:58:43Z"),
            ]],
            "events",
            "APP",
            &DatabaseType::Oracle,
            None,
        );

        assert_eq!(
            sql,
            "INSERT INTO \"APP\".\"events\" (\"id\", \"created_on\", \"created_at\", \"raw_text\") VALUES\n(1, TO_DATE('2022-08-25 09:58:43', 'YYYY-MM-DD HH24:MI:SS'), TO_TIMESTAMP('2022-08-25 09:58:43', 'YYYY-MM-DD HH24:MI:SS'), '2022-08-25T09:58:43Z')"
        );
        assert_eq!(
            escape_value_typed(&json!("2022-08-25T00:00:00Z"), &DatabaseType::Oracle, Some("DATE")),
            "DATE '2022-08-25'"
        );
        assert_eq!(
            escape_value_typed(
                &json!("2022-08-25T09:58:43.123456+08:00"),
                &DatabaseType::Oracle,
                Some("TIMESTAMP(6) WITH TIME ZONE")
            ),
            "TO_TIMESTAMP_TZ('2022-08-25 09:58:43.123456 +08:00', 'YYYY-MM-DD HH24:MI:SS.FF TZH:TZM')"
        );
    }

    #[test]
    fn mysql_insert_formats_numeric_strings_from_numeric_columns_as_numeric_literals() {
        let sql = generate_insert_typed(
            &[
                String::from("id"),
                String::from("amount"),
                String::from("quantity"),
                String::from("text_id"),
                String::from("bad_number"),
                String::from("missing"),
            ],
            &[
                Some(String::from("bigint(20)")),
                Some(String::from("decimal(10,2)")),
                Some(String::from("int unsigned")),
                Some(String::from("varchar(64)")),
                Some(String::from("bigint(20)")),
                Some(String::from("bigint(20)")),
            ],
            &[vec![
                json!("1234567890123"),
                json!("12.34"),
                json!("42"),
                json!("123"),
                json!("not-a-number"),
                serde_json::Value::Null,
            ]],
            "orders",
            "",
            &DatabaseType::Mysql,
            None,
        );

        assert_eq!(
            sql,
            "INSERT INTO `orders` (`id`, `amount`, `quantity`, `text_id`, `bad_number`, `missing`) VALUES\n(1234567890123, 12.34, 42, '123', 'not-a-number', NULL)"
        );
    }

    #[test]
    fn mysql_upsert_formats_numeric_strings_from_numeric_columns_as_numeric_literals() {
        let sql = generate_upsert_typed(
            &[String::from("id"), String::from("amount")],
            &[Some(String::from("bigint(20)")), Some(String::from("decimal(10,2)"))],
            &[vec![json!("1234567890123"), json!("12.34")]],
            "orders",
            "",
            &DatabaseType::Mysql,
            &[String::from("id")],
            None,
        );

        assert_eq!(
            sql,
            "INSERT INTO `orders` (`id`, `amount`) VALUES\n(1234567890123, 12.34)\nON DUPLICATE KEY UPDATE `amount` = VALUES(`amount`)"
        );
    }

    #[test]
    fn sqlserver_insert_prefixes_string_literals_as_unicode() {
        let sql = generate_insert_typed(
            &[String::from("name"), String::from("note")],
            &[Some(String::from("nvarchar(100)")), Some(String::from("varchar(100)"))],
            &[vec![json!("Tiếng Việt"), json!("O'Brien")]],
            "customers",
            "dbo",
            &DatabaseType::SqlServer,
            None,
        );

        assert_eq!(sql, "INSERT INTO [dbo].[customers] ([name], [note]) VALUES\n(N'Tiếng Việt', N'O''Brien')");
    }

    #[test]
    fn sqlserver_insert_preserves_backslashes_control_characters_quotes_and_unicode() {
        let sql = generate_insert_typed(
            &[String::from("escape_sequence"), String::from("line_break"), String::from("quote_and_unicode")],
            &[
                Some(String::from("nvarchar(max)")),
                Some(String::from("nvarchar(max)")),
                Some(String::from("nvarchar(max)")),
            ],
            &[vec![json!(r#"\n"#), json!("line1\r\nline2"), json!("O'Brien / Tiếng Việt")]],
            "notes",
            "dbo",
            &DatabaseType::SqlServer,
            None,
        );

        assert_eq!(
            sql,
            "INSERT INTO [dbo].[notes] ([escape_sequence], [line_break], [quote_and_unicode]) VALUES\n(N'\\n', N'line1\r\nline2', N'O''Brien / Tiếng Việt')"
        );
    }

    #[test]
    fn sqlserver_insert_formats_datetime_literals_with_supported_precision() {
        let sql = generate_insert_typed(
            &[String::from("id"), String::from("date1"), String::from("date2"), String::from("note")],
            &[
                Some(String::from("int")),
                Some(String::from("datetime")),
                Some(String::from("datetime2(7)")),
                Some(String::from("nvarchar(100)")),
            ],
            &[vec![
                json!(1),
                json!("2026-06-29 10:11:12.896666666"),
                json!("2026-06-29T10:11:12.8966666Z"),
                json!("2026-06-29 10:11:12.896666666"),
            ]],
            "test",
            "dbo",
            &DatabaseType::SqlServer,
            None,
        );

        assert_eq!(
            sql,
            "INSERT INTO [dbo].[test] ([id], [date1], [date2], [note]) VALUES\n(1, N'2026-06-29 10:11:12.897', N'2026-06-29 10:11:12.8966666', N'2026-06-29 10:11:12.896666666')"
        );
    }

    #[test]
    fn sqlserver_insert_formats_bit_booleans_as_numeric_literals() {
        let sql = generate_insert_typed(
            &[String::from("enabled"), String::from("deleted")],
            &[Some(String::from("bit")), Some(String::from("BIT"))],
            &[vec![json!(true), json!(false)]],
            "flags",
            "dbo",
            &DatabaseType::SqlServer,
            None,
        );

        assert_eq!(sql, "INSERT INTO [dbo].[flags] ([enabled], [deleted]) VALUES\n(1, 0)");
    }

    #[test]
    fn sqlserver_insert_formats_prefixed_hex_for_varbinary_columns() {
        let sql = generate_insert_typed(
            &[String::from("payload"), String::from("note")],
            &[Some(String::from("varbinary(max)")), Some(String::from("nvarchar(64)"))],
            &[vec![json!("0x0001ABff"), json!("0x0001ABff")]],
            "files",
            "dbo",
            &DatabaseType::SqlServer,
            None,
        );

        assert_eq!(sql, "INSERT INTO [dbo].[files] ([payload], [note]) VALUES\n(0x0001ABff, N'0x0001ABff')");
    }

    #[test]
    fn sqlserver_insert_explicitly_converts_plain_text_for_varbinary_columns() {
        let sql = generate_insert_typed(
            &[String::from("payload")],
            &[Some(String::from("varbinary(max)"))],
            &[vec![json!("O'Brien")]],
            "files",
            "dbo",
            &DatabaseType::SqlServer,
            None,
        );

        assert_eq!(sql, "INSERT INTO [dbo].[files] ([payload]) VALUES\n(CONVERT(varbinary(max), N'O''Brien'))");
    }

    #[test]
    fn dameng_insert_formats_bit_booleans_as_numeric_literals() {
        let sql = generate_insert_typed(
            &[String::from("enabled"), String::from("deleted"), String::from("optional")],
            &[Some(String::from("BIT")), Some(String::from("bit")), Some(String::from("BIT"))],
            &[vec![json!(true), json!(false), serde_json::Value::Null]],
            "flags",
            "DBX_TEST",
            &DatabaseType::Dameng,
            None,
        );

        assert_eq!(
            sql,
            "INSERT INTO \"DBX_TEST\".\"flags\" (\"enabled\", \"deleted\", \"optional\") VALUES\n(1, 0, NULL)"
        );
        assert!(!sql.contains("TRUE"));
        assert!(!sql.contains("FALSE"));
    }

    #[test]
    fn sqlserver_upsert_formats_bit_booleans_as_numeric_literals() {
        let sql = generate_upsert_typed(
            &[String::from("id"), String::from("enabled")],
            &[Some(String::from("int")), Some(String::from("bit"))],
            &[vec![json!(1), json!(true)]],
            "flags",
            "dbo",
            &DatabaseType::SqlServer,
            &[String::from("id")],
            None,
        );

        assert!(sql.contains("USING (VALUES\n(1, 1)\n)"));
        assert!(!sql.contains("TRUE"));
        assert!(!sql.contains("FALSE"));
    }

    #[test]
    fn postgres_insert_preserves_json_escape_sequences() {
        let sql = generate_insert_typed(
            &[String::from("payload")],
            &[Some(String::from("jsonb"))],
            &[vec![json!(r#"{"message":"hello\nworld"}"#)]],
            "events",
            "public",
            &DatabaseType::Postgres,
            None,
        );

        assert_eq!(
            sql,
            r#"INSERT INTO "public"."events" ("payload") VALUES
(E'{"message":"hello\\nworld"}')"#
        );
    }

    #[test]
    fn postgres_insert_preserves_text_backslashes() {
        let sql = generate_insert_typed(
            &[String::from("path")],
            &[Some(String::from("text"))],
            &[vec![json!(r#"C:\tmp\file.txt"#)]],
            "files",
            "public",
            &DatabaseType::Postgres,
            None,
        );

        assert_eq!(
            sql,
            r#"INSERT INTO "public"."files" ("path") VALUES
(E'C:\\tmp\\file.txt')"#
        );
    }

    #[test]
    fn postgres_insert_formats_bytea_prefixed_hex_as_binary_literal() {
        let sql = generate_insert_typed(
            &[String::from("id"), String::from("payload"), String::from("note")],
            &[Some(String::from("integer")), Some(String::from("BYTEA")), Some(String::from("text"))],
            &[vec![json!(1), json!("0x48656c6c6f"), json!("0x48656c6c6f")]],
            "files",
            "public",
            &DatabaseType::Postgres,
            None,
        );

        assert_eq!(
            sql,
            r#"INSERT INTO "public"."files" ("id", "payload", "note") VALUES
(1, decode('48656c6c6f', 'hex'), '0x48656c6c6f')"#
        );
    }

    #[test]
    fn mysql_insert_formats_blob_prefixed_hex_as_binary_literal() {
        let sql = generate_insert_typed(
            &[String::from("id"), String::from("payload"), String::from("empty_blob"), String::from("note")],
            &[
                Some(String::from("int")),
                Some(String::from("MEDIUMBLOB")),
                Some(String::from("blob")),
                Some(String::from("varchar(64)")),
            ],
            &[vec![json!(1), json!("0x0001ABff"), json!("0X"), json!("0x0001ABff")]],
            "files",
            "",
            &DatabaseType::Mysql,
            None,
        );

        assert_eq!(
            sql,
            r#"INSERT INTO `files` (`id`, `payload`, `empty_blob`, `note`) VALUES
(1, 0x0001ABff, X'', '0x0001ABff')"#
        );
    }

    #[test]
    fn mysql_insert_keeps_invalid_blob_hex_as_string_literal() {
        let sql = generate_insert_typed(
            &[String::from("id"), String::from("payload")],
            &[Some(String::from("int")), Some(String::from("mediumblob"))],
            &[vec![json!(1), json!("0xnothex")]],
            "files",
            "",
            &DatabaseType::Mysql,
            None,
        );

        assert_eq!(
            sql,
            r#"INSERT INTO `files` (`id`, `payload`) VALUES
(1, '0xnothex')"#
        );
    }

    #[test]
    fn mysql_insert_keeps_backslash_escape_style() {
        let sql = generate_insert_typed(
            &[String::from("path")],
            &[Some(String::from("varchar(255)"))],
            &[vec![json!(r#"C:\tmp\file.txt"#)]],
            "files",
            "",
            &DatabaseType::Mysql,
            None,
        );

        assert_eq!(
            sql,
            r#"INSERT INTO `files` (`path`) VALUES
('C:\\tmp\\file.txt')"#
        );
    }

    #[test]
    fn postgres_insert_escapes_control_characters_quotes_and_backslashes() {
        let sql = generate_insert_typed(
            &[
                String::from("line_break"),
                String::from("carriage_return"),
                String::from("quote"),
                String::from("path"),
                String::from("plain"),
            ],
            &[
                Some(String::from("text")),
                Some(String::from("text")),
                Some(String::from("text")),
                Some(String::from("text")),
                Some(String::from("text")),
            ],
            &[vec![json!("line1\nline2"), json!("line1\rline2"), json!("O'Hara"), json!(r"C:\tmp"), json!("plain")]],
            "notes",
            "public",
            &DatabaseType::Postgres,
            None,
        );

        assert_eq!(
            sql,
            r#"INSERT INTO "public"."notes" ("line_break", "carriage_return", "quote", "path", "plain") VALUES
(E'line1\nline2', E'line1\rline2', 'O''Hara', E'C:\\tmp', 'plain')"#
        );
    }

    #[test]
    fn postgres_insert_formats_whole_number_values_as_integer_literals() {
        let sql = generate_insert_typed(
            &[String::from("small_value"), String::from("integer_value"), String::from("big_value")],
            &[Some(String::from("smallint")), Some(String::from("integer")), Some(String::from("bigint"))],
            &[vec![json!(1.0), json!(-2.0), json!(3.0)]],
            "numbers",
            "public",
            &DatabaseType::Postgres,
            None,
        );

        assert_eq!(
            sql,
            "INSERT INTO \"public\".\"numbers\" (\"small_value\", \"integer_value\", \"big_value\") VALUES\n(1, -2, 3)"
        );
    }

    #[test]
    fn postgres_integer_literal_normalization_preserves_non_whole_and_out_of_range_values() {
        let scientific: serde_json::Value = serde_json::from_str("1e20").unwrap();
        let out_of_range: serde_json::Value = serde_json::from_str("9223372036854775808.0").unwrap();

        assert_eq!(escape_value_typed(&json!("1.0"), &DatabaseType::Postgres, Some("smallint")), "1");
        assert_eq!(escape_value_typed(&json!("-2.0"), &DatabaseType::Postgres, Some("integer")), "-2");
        assert_eq!(escape_value_typed(&json!("3.0"), &DatabaseType::Postgres, Some("bigint")), "3");
        assert_eq!(escape_value_typed(&json!(1.25), &DatabaseType::Postgres, Some("smallint")), "1.25");
        assert_eq!(escape_value_typed(&json!("1.25"), &DatabaseType::Postgres, Some("smallint")), "'1.25'");
        assert_eq!(escape_value_typed(&scientific, &DatabaseType::Postgres, Some("bigint")), "1e+20");
        assert_eq!(escape_value_typed(&json!("1e3"), &DatabaseType::Postgres, Some("bigint")), "'1e3'");
        assert_eq!(escape_value_typed(&out_of_range, &DatabaseType::Postgres, Some("bigint")), "9223372036854775808.0");
        assert_eq!(
            escape_value_typed(&json!("9223372036854775808.0"), &DatabaseType::Postgres, Some("bigint")),
            "'9223372036854775808.0'"
        );
        assert_eq!(escape_value_typed(&json!("32768.0"), &DatabaseType::Postgres, Some("smallint")), "'32768.0'");
        assert_eq!(
            escape_value_typed(&json!("2147483648.0"), &DatabaseType::Postgres, Some("integer")),
            "'2147483648.0'"
        );
        assert_eq!(escape_value_typed(&json!("1.0"), &DatabaseType::Postgres, Some("text")), "'1.0'");
        assert_eq!(escape_value_typed(&json!("1.0"), &DatabaseType::Postgres, Some("numeric")), "'1.0'");
        assert_eq!(escape_value_typed(&json!("1.0"), &DatabaseType::Postgres, None), "'1.0'");
    }

    #[test]
    fn oracle_single_row_insert_keeps_values_shape() {
        let sql = generate_insert_typed(
            &[String::from("id"), String::from("name")],
            &[Some(String::from("number")), Some(String::from("varchar2(64)"))],
            &[vec![json!(1), json!("Ada")]],
            "INSTR_CATEGORY",
            "APP",
            &DatabaseType::Oracle,
            None,
        );

        assert_eq!(
            sql,
            r#"INSERT INTO "APP"."INSTR_CATEGORY" ("id", "name") VALUES
(1, 'Ada')"#
        );
    }

    #[test]
    fn oracle_multi_row_insert_uses_insert_all() {
        let sql = generate_insert_typed(
            &[String::from("id"), String::from("name")],
            &[Some(String::from("number")), Some(String::from("varchar2(64)"))],
            &[vec![json!(1), json!("Ada")], vec![json!(2), json!("O'Brien")]],
            "INSTR_CATEGORY",
            "APP",
            &DatabaseType::Oracle,
            None,
        );

        assert_eq!(
            sql,
            r#"INSERT ALL
INTO "APP"."INSTR_CATEGORY" ("id", "name") VALUES (1, 'Ada')
INTO "APP"."INSTR_CATEGORY" ("id", "name") VALUES (2, 'O''Brien')
SELECT 1 FROM dual"#
        );
    }

    #[test]
    fn oracle_transfer_write_batches_limit_insert_all_rows() {
        let rows = (0..(MAX_ORACLE_INSERT_ALL_ROWS + 1)).map(|index| vec![json!(index)]).collect::<Vec<_>>();
        let statements = generate_transfer_write_sql_batches(
            &TransferMode::Append,
            &[String::from("id")],
            &[Some(String::from("number"))],
            &rows,
            "INSTR_CATEGORY",
            "APP",
            &DatabaseType::Oracle,
            &[],
            None,
            false,
            false,
        )
        .unwrap();

        assert_eq!(statements.len(), 2);
        assert_eq!(statements[0].matches("\nINTO ").count(), MAX_ORACLE_INSERT_ALL_ROWS);
        assert!(statements[0].starts_with("INSERT ALL\nINTO "));
        assert!(statements[0].ends_with("SELECT 1 FROM dual"));
    }

    #[test]
    fn transfer_write_sql_batches_split_large_insert_statements() {
        let rows = (0..4).map(|index| vec![json!(index), json!("x".repeat(180 * 1024))]).collect::<Vec<_>>();
        let statements = generate_transfer_write_sql_batches(
            &TransferMode::Append,
            &[String::from("id"), String::from("payload")],
            &[Some(String::from("int")), Some(String::from("text"))],
            &rows,
            "events",
            "",
            &DatabaseType::Mysql,
            &[],
            None,
            false,
            false,
        )
        .unwrap();

        assert!(statements.len() > 1);
        assert!(statements.iter().all(|sql| sql.starts_with("INSERT INTO `events`")));
    }

    #[test]
    fn mysql_sql_batch_allows_one_row_over_soft_target() {
        let rows = vec![vec![json!("x".repeat(256))]];
        let limits = SqlBatchLimits { max_rows: 100, target_sql_bytes: 128, hard_sql_bytes: Some(1024) };

        let batches = generate_insert_typed_sql_batches(
            &[String::from("payload")],
            &[Some(String::from("text"))],
            &rows,
            "events",
            "",
            &DatabaseType::Mysql,
            None,
            limits,
        )
        .unwrap();

        assert_eq!(batches.len(), 1);
        assert_eq!(batches[0].1, 1);
    }

    #[test]
    fn mysql_sql_batch_rejects_one_row_over_known_hard_limit() {
        let rows = vec![vec![json!("x".repeat(256))]];
        let limits = SqlBatchLimits { max_rows: 100, target_sql_bytes: 128, hard_sql_bytes: Some(200) };

        let error = generate_insert_typed_sql_batches(
            &[String::from("payload")],
            &[Some(String::from("text"))],
            &rows,
            "events",
            "",
            &DatabaseType::Mysql,
            None,
            limits,
        )
        .unwrap_err();

        assert!(error.contains("row 1"));
        assert!(error.contains("200 byte hard limit"));
    }

    #[test]
    fn sqlserver_insert_batches_enforce_values_row_limit() {
        let rows = (0..(MAX_SQLSERVER_INSERT_ROWS + 1)).map(|index| vec![json!(index)]).collect::<Vec<_>>();

        let batches = generate_insert_typed_sql_batches(
            &[String::from("id")],
            &[Some(String::from("int"))],
            &rows,
            "events",
            "dbo",
            &DatabaseType::SqlServer,
            None,
            SqlBatchLimits::for_database(&DatabaseType::SqlServer, rows.len()),
        )
        .unwrap();

        assert_eq!(batches.iter().map(|(_, row_count)| *row_count).collect::<Vec<_>>(), vec![1000, 1]);
    }

    #[test]
    fn sqlserver_insert_batches_measure_unicode_sql_as_utf16() {
        let rows = (0..2).map(|_| vec![json!("x".repeat(140 * 1024))]).collect::<Vec<_>>();

        let batches = generate_insert_typed_sql_batches(
            &[String::from("payload")],
            &[Some(String::from("nvarchar(max)"))],
            &rows,
            "events",
            "dbo",
            &DatabaseType::SqlServer,
            None,
            SqlBatchLimits::for_database(&DatabaseType::SqlServer, rows.len()),
        )
        .unwrap();

        assert_eq!(batches.iter().map(|(_, row_count)| *row_count).collect::<Vec<_>>(), vec![1, 1]);
    }

    #[test]
    fn sqlserver_sql_byte_count_uses_utf16_code_units() {
        assert_eq!(sql_text_bytes("AA\u{8d8a}\u{1f600}", &DatabaseType::SqlServer), 10);
        assert_eq!(sql_text_bytes("AA\u{8d8a}\u{1f600}", &DatabaseType::Postgres), 9);
    }

    #[test]
    fn transfer_write_sql_batches_keep_existing_upsert_sql_shape() {
        let statements = generate_transfer_write_sql_batches(
            &TransferMode::Upsert,
            &[String::from("id"), String::from("name")],
            &[Some(String::from("int")), Some(String::from("varchar(64)"))],
            &[vec![json!(1), json!("Ada")]],
            "users",
            "",
            &DatabaseType::Mysql,
            &[String::from("id")],
            None,
            false,
            false,
        )
        .unwrap();

        assert_eq!(statements.len(), 1);
        assert!(statements[0].contains("ON DUPLICATE KEY UPDATE"));
    }

    #[test]
    fn mysql_spatial_transfer_reuses_validated_wkb_markers_for_all_modes() {
        let columns = [String::from("id"), String::from("location"), String::from("name")];
        let column_types = [Some(String::from("int")), Some(String::from("point")), Some(String::from("varchar(32)"))];
        let rows = [vec![json!(1), json!("DBX_WKB:4326:0101000000000000000000F03F0000000000000040"), json!("alpha")]];

        for mode in [TransferMode::Append, TransferMode::Overwrite, TransferMode::Upsert] {
            let statements = generate_transfer_write_sql_batches(
                &mode,
                &columns,
                &column_types,
                &rows,
                "places",
                "",
                &DatabaseType::Mysql,
                &[String::from("id")],
                None,
                false,
                true,
            )
            .unwrap();

            assert_eq!(statements.len(), 1);
            assert!(statements[0].contains("ST_GeomFromWKB(0x0101000000000000000000F03F0000000000000040, 4326)"));
            assert!(statements[0].contains("'alpha'"));
            if mode == TransferMode::Upsert {
                assert!(statements[0].contains("ON DUPLICATE KEY UPDATE"));
            }
        }
    }

    #[test]
    fn mysql_spatial_transfer_rejects_invalid_markers_and_keeps_public_insert_shape() {
        let invalid = json!("DBX_WKB:4326:0101000000");
        let transfer = generate_transfer_write_sql_batches(
            &TransferMode::Append,
            &[String::from("location")],
            &[Some(String::from("point"))],
            &[vec![invalid.clone()]],
            "places",
            "",
            &DatabaseType::Mysql,
            &[],
            None,
            false,
            true,
        )
        .unwrap();
        let public = generate_insert_typed(
            &[String::from("location")],
            &[Some(String::from("point"))],
            &[vec![invalid]],
            "places",
            "",
            &DatabaseType::Mysql,
            None,
        );

        assert_eq!(transfer, vec!["INSERT INTO `places` (`location`) VALUES\n('DBX_WKB:4326:0101000000')"]);
        assert_eq!(public, transfer[0]);
        assert!(!transfer[0].contains("ST_GeomFromWKB"));
    }

    #[test]
    fn mysql_spatial_transfer_projection_is_native_mysql_to_mysql_only() {
        let sql = "SELECT `id`, `location` FROM `places` ORDER BY `id` LIMIT 2 OFFSET 0".to_string();
        let columns = [String::from("id"), String::from("location")];
        let column_types = [Some(String::from("int")), Some(String::from("point"))];

        let (native_sql, native_markers) = mysql_spatial_transfer_select_sql(
            sql.clone(),
            &columns,
            &column_types,
            &DatabaseType::Mysql,
            &DatabaseType::Mysql,
        );
        assert!(native_markers);
        assert!(native_sql.contains("CONCAT('DBX_WKB:', ST_SRID(`location`), ':', HEX(ST_AsWKB(`location`)))"));
        assert!(native_sql.ends_with("ORDER BY `id` LIMIT 2 OFFSET 0"));

        let nonspatial_types = [Some(String::from("int")), Some(String::from("varchar(32)"))];
        assert_eq!(
            mysql_spatial_transfer_select_sql(
                sql.clone(),
                &columns,
                &nonspatial_types,
                &DatabaseType::Mysql,
                &DatabaseType::Mysql,
            ),
            (sql.clone(), false)
        );

        for (source, target) in [
            (DatabaseType::Mysql, DatabaseType::Postgres),
            (DatabaseType::Postgres, DatabaseType::Mysql),
            (DatabaseType::Doris, DatabaseType::Mysql),
        ] {
            assert_eq!(
                mysql_spatial_transfer_select_sql(sql.clone(), &columns, &column_types, &source, &target),
                (sql.clone(), false)
            );
        }
    }

    #[test]
    fn postgres_transfer_insert_overrides_generated_always_identity_values() {
        for mode in [TransferMode::Append, TransferMode::Overwrite] {
            let statements = generate_transfer_write_sql_batches(
                &mode,
                &[String::from("id"), String::from("name")],
                &[Some(String::from("bigint")), Some(String::from("text"))],
                &[vec![json!(42), json!("Ada")]],
                "users",
                "public",
                &DatabaseType::Postgres,
                &[],
                None,
                true,
                false,
            )
            .unwrap();

            assert_eq!(statements.len(), 1);
            assert_eq!(
                statements[0],
                "INSERT INTO \"public\".\"users\" (\"id\", \"name\") OVERRIDING SYSTEM VALUE VALUES\n(42, 'Ada')"
            );
        }
    }

    #[test]
    fn postgres_transfer_upsert_overrides_generated_always_identity_values() {
        let statements = generate_transfer_write_sql_batches(
            &TransferMode::Upsert,
            &[String::from("id"), String::from("name")],
            &[Some(String::from("bigint")), Some(String::from("text"))],
            &[vec![json!(42), json!("Ada")]],
            "users",
            "public",
            &DatabaseType::Postgres,
            &[String::from("id")],
            None,
            true,
            false,
        )
        .unwrap();

        assert_eq!(statements.len(), 1);
        assert_eq!(
            statements[0],
            "INSERT INTO \"public\".\"users\" (\"id\", \"name\") OVERRIDING SYSTEM VALUE VALUES\n(42, 'Ada')\nON CONFLICT (\"id\") DO UPDATE SET \"name\" = EXCLUDED.\"name\""
        );
    }

    #[test]
    fn postgres_transfer_without_generated_always_identity_keeps_sql_shape() {
        let statements = generate_transfer_write_sql_batches(
            &TransferMode::Append,
            &[String::from("name")],
            &[Some(String::from("text"))],
            &[vec![json!("Ada")]],
            "users",
            "public",
            &DatabaseType::Postgres,
            &[],
            None,
            false,
            false,
        )
        .unwrap();

        assert_eq!(statements, vec!["INSERT INTO \"public\".\"users\" (\"name\") VALUES\n('Ada')"]);
    }

    #[test]
    fn postgres_system_value_override_is_not_applied_to_other_dialects() {
        let statements = generate_transfer_write_sql_batches(
            &TransferMode::Append,
            &[String::from("id")],
            &[Some(String::from("bigint"))],
            &[vec![json!(42)]],
            "users",
            "public",
            &DatabaseType::Kingbase,
            &[],
            None,
            true,
            false,
        )
        .unwrap();

        assert_eq!(statements, vec!["INSERT INTO \"public\".\"users\" (\"id\") VALUES\n(42)"]);
    }

    #[test]
    fn postgres_non_transfer_insert_keeps_existing_sql_shape() {
        let sql = generate_insert(
            &[String::from("id"), String::from("name")],
            &[vec![json!(42), json!("Ada")]],
            "users",
            "public",
            &DatabaseType::Postgres,
        );

        assert_eq!(sql, "INSERT INTO \"public\".\"users\" (\"id\", \"name\") VALUES\n(42, 'Ada')");
    }

    #[test]
    fn database_from_pool_key_handles_session_scoped_keys() {
        assert_eq!(database_from_pool_key("conn:analytics"), Some("analytics"));
        assert_eq!(database_from_pool_key("conn:analytics:session:editor-1"), Some("analytics"));
        assert_eq!(database_from_pool_key("conn"), None);
        assert_eq!(database_from_pool_key("conn:analytics:catalog:hive"), Some("analytics"));
        assert_eq!(database_from_pool_key("conn:catalog:hive"), None);
        assert_eq!(catalog_from_pool_key("conn:catalog:hive"), Some("hive"));
        assert_eq!(catalog_from_pool_key("conn:ads:catalog:paimon"), Some("paimon"));
        assert_eq!(catalog_from_pool_key("conn:ads"), None);
    }

    #[test]
    fn resolve_external_transfer_catalog_skips_builtin_catalogs() {
        assert_eq!(resolve_external_transfer_catalog(Some("hive"), &DatabaseType::StarRocks), Some("hive"));
        assert_eq!(resolve_external_transfer_catalog(Some("default_catalog"), &DatabaseType::StarRocks), None);
        assert_eq!(resolve_external_transfer_catalog(Some("internal"), &DatabaseType::Doris), None);
        // MySQL db_type is included so StarRocks saved as mysql+driver_profile still
        // gets 3-part catalog qualification (UI only sends catalog for capable engines).
        assert_eq!(resolve_external_transfer_catalog(Some("hive"), &DatabaseType::Mysql), Some("hive"));
        assert_eq!(resolve_external_transfer_catalog(Some("hive"), &DatabaseType::Postgres), None);
    }

    #[test]
    fn resolve_external_transfer_catalog_for_config_accepts_starrocks_driver_profile() {
        let config = crate::models::connection::ConnectionConfig {
            docs_notes_path: None,
            id: "sr".to_string(),
            name: "sr".to_string(),
            note: String::new(),
            db_type: DatabaseType::Mysql,
            driver_profile: Some("starrocks".to_string()),
            driver_label: None,
            url_params: None,
            agent_java_options: Vec::new(),
            host: "127.0.0.1".to_string(),
            port: 9030,
            username: String::new(),
            password: String::new(),
            database: None,
            default_schema: None,
            visible_databases: None,
            visible_schemas: None,
            show_system_schemas: false,
            attached_databases: Vec::new(),
            init_script: None,
            color: None,
            transport_layers: Vec::new(),
            connect_timeout_secs: 5,
            query_timeout_secs: 30,
            idle_timeout_secs: 60,
            keepalive_interval_secs: 0,
            ssl: false,
            ca_cert_path: String::new(),
            client_cert_path: String::new(),
            client_key_path: String::new(),
            sysdba: false,
            oracle_connection_type: None,
            connection_string: None,
            redis_connection_mode: None,
            redis_sentinel_master: String::new(),
            redis_sentinel_nodes: String::new(),
            redis_sentinel_username: String::new(),
            redis_sentinel_password: String::new(),
            redis_sentinel_tls: false,
            redis_cluster_nodes: String::new(),
            redis_key_separator: crate::models::connection::default_redis_key_separator(),
            redis_scan_page_size: None,
            redis_database_aliases: Default::default(),
            etcd_endpoints: String::new(),
            gbase_server: String::new(),
            informix_server: String::new(),
            external_config: None,
            jdbc_driver_class: None,
            jdbc_driver_paths: Vec::new(),
            one_time: false,
            save_password: true,
            read_only: false,
            is_production: false,
            production_databases: vec![],
            database_info: None,
        };
        assert_eq!(resolve_external_transfer_catalog_for_config(Some("paimon"), &config), Some("paimon"));
        assert_eq!(resolve_external_transfer_catalog_for_config(Some("default_catalog"), &config), None);
    }

    #[test]
    fn transfer_read_retry_policy_retries_connection_errors() {
        assert_eq!(
            transfer_pool_error_action(
                TransferExecutionSafety::ReadOnlyRetryable,
                Some(DatabaseType::Postgres),
                "connection reset by peer"
            ),
            PoolErrorAction::ReconnectAndRetry
        );
    }

    #[test]
    fn transfer_write_retry_policy_discards_without_replaying_batch() {
        assert_eq!(
            transfer_pool_error_action(
                TransferExecutionSafety::WriteNoReplay,
                Some(DatabaseType::Postgres),
                "connection reset by peer"
            ),
            PoolErrorAction::Discard
        );
    }

    #[test]
    fn map_column_type_preserves_longtext_for_mysql_target() {
        assert_eq!(map_column_type("longtext", &DatabaseType::Mysql, &DatabaseType::Mysql), "longtext");
    }

    #[test]
    fn map_column_type_preserves_mediumtext_for_mysql_target() {
        assert_eq!(map_column_type("mediumtext", &DatabaseType::Mysql, &DatabaseType::Mysql), "mediumtext");
    }

    #[test]
    fn map_column_type_preserves_longblob_for_mysql_target() {
        assert_eq!(map_column_type("longblob", &DatabaseType::Mysql, &DatabaseType::Mysql), "longblob");
    }

    #[test]
    fn map_column_type_preserves_mediumblob_for_mysql_target() {
        assert_eq!(map_column_type("mediumblob", &DatabaseType::Mysql, &DatabaseType::Mysql), "mediumblob");
    }

    #[test]
    fn map_column_type_preserves_same_database_type() {
        assert_eq!(map_column_type("int unsigned", &DatabaseType::Mysql, &DatabaseType::Mysql), "int unsigned");
        assert_eq!(
            map_column_type("int unsigned zerofill", &DatabaseType::Mysql, &DatabaseType::Mysql),
            "int unsigned zerofill"
        );
        assert_eq!(map_column_type("bigint unsigned", &DatabaseType::Mysql, &DatabaseType::Mysql), "bigint unsigned");
        assert_eq!(
            map_column_type("bigint unsigned zerofill", &DatabaseType::Mysql, &DatabaseType::Mysql),
            "bigint unsigned zerofill"
        );
    }

    #[test]
    fn map_column_type_preserves_numeric_type_from_mysql_to_postgres() {
        assert_eq!(map_column_type("int unsigned", &DatabaseType::Mysql, &DatabaseType::Postgres), "INTEGER");
        assert_eq!(map_column_type("int unsigned zerofill", &DatabaseType::Mysql, &DatabaseType::Postgres), "INTEGER");
        assert_eq!(map_column_type("bigint unsigned", &DatabaseType::Mysql, &DatabaseType::Postgres), "BIGINT");
        assert_eq!(
            map_column_type("bigint unsigned zerofill", &DatabaseType::Mysql, &DatabaseType::Postgres),
            "BIGINT"
        );
    }

    #[test]
    fn map_column_type_longtext_falls_back_to_text_for_non_mysql_target() {
        assert_eq!(map_column_type("longtext", &DatabaseType::Mysql, &DatabaseType::Postgres), "TEXT");
    }

    #[test]
    fn map_column_type_longblob_falls_back_for_non_mysql_target() {
        assert_eq!(map_column_type("longblob", &DatabaseType::Mysql, &DatabaseType::Postgres), "BYTEA");
    }

    #[test]
    fn parse_mysql_row_error_extracts_row_number() {
        let err = "ERROR 22001 (1406): Data too long column 'content' at row 8";
        assert_eq!(parse_mysql_row_error(err), Some(8));
    }

    #[test]
    fn parse_mysql_row_error_returns_none_for_non_mysql_error() {
        assert_eq!(parse_mysql_row_error("some other error"), None);
    }

    #[test]
    fn mysql_create_table_preserves_auto_increment_primary_key() {
        let cols = vec![
            db::ColumnInfo {
                is_primary_key: true,
                is_nullable: false,
                extra: Some("auto_increment".to_string()),
                ..test_column("id", "INT")
            },
            db::ColumnInfo { is_nullable: false, ..test_column("name", "varchar(64)") },
        ];

        let ddl =
            generate_create_table_ddl(&cols, "users", "", "", &DatabaseType::Mysql, &DatabaseType::Mysql, None, None);

        assert!(ddl.contains("`id` INT NOT NULL AUTO_INCREMENT"), "ddl: {ddl}");
        assert!(ddl.contains("PRIMARY KEY (`id`)"), "ddl: {ddl}");
    }

    #[test]
    fn mysql_create_table_preserves_numeric_default_zero() {
        let cols = vec![db::ColumnInfo {
            is_nullable: false,
            column_default: Some("0".to_string()),
            ..test_column("status", "tinyint")
        }];

        let ddl =
            generate_create_table_ddl(&cols, "items", "", "", &DatabaseType::Mysql, &DatabaseType::Mysql, None, None);

        assert!(ddl.contains("DEFAULT 0"), "ddl: {ddl}");
        assert!(!ddl.contains("'0'"), "ddl should not quote numeric default: {ddl}");
    }

    #[test]
    fn mysql_create_table_quotes_string_default_with_escape() {
        let cols =
            vec![db::ColumnInfo { column_default: Some("o'clock".to_string()), ..test_column("label", "varchar(32)") }];

        let ddl =
            generate_create_table_ddl(&cols, "items", "", "", &DatabaseType::Mysql, &DatabaseType::Mysql, None, None);

        assert!(ddl.contains("DEFAULT 'o''clock'"), "ddl: {ddl}");
    }

    #[test]
    fn mysql_create_table_keeps_current_timestamp_default_and_on_update() {
        let cols = vec![db::ColumnInfo {
            is_nullable: false,
            column_default: Some("CURRENT_TIMESTAMP".to_string()),
            extra: Some("DEFAULT_GENERATED on update CURRENT_TIMESTAMP".to_string()),
            ..test_column("updated_at", "timestamp")
        }];

        let ddl =
            generate_create_table_ddl(&cols, "items", "", "", &DatabaseType::Mysql, &DatabaseType::Mysql, None, None);

        assert!(ddl.contains("DEFAULT CURRENT_TIMESTAMP"), "ddl: {ddl}");
        assert!(ddl.contains("ON UPDATE CURRENT_TIMESTAMP"), "ddl: {ddl}");
        assert!(ddl.contains("NOT NULL"), "ddl: {ddl}");
        assert!(!ddl.contains("DEFAULT_GENERATED"), "ddl should not leak DEFAULT_GENERATED: {ddl}");
    }

    #[test]
    fn mysql_create_table_keeps_current_timestamp_with_fsp() {
        let cols = vec![db::ColumnInfo {
            is_nullable: false,
            column_default: Some("CURRENT_TIMESTAMP(6)".to_string()),
            ..test_column("created_at", "timestamp(6)")
        }];

        let ddl =
            generate_create_table_ddl(&cols, "items", "", "", &DatabaseType::Mysql, &DatabaseType::Mysql, None, None);

        assert!(ddl.contains("DEFAULT CURRENT_TIMESTAMP(6)"), "ddl: {ddl}");
    }

    #[test]
    fn mysql_create_table_emits_on_update_without_default() {
        let cols = vec![db::ColumnInfo {
            is_nullable: false,
            extra: Some("on update CURRENT_TIMESTAMP(3)".to_string()),
            ..test_column("touched_at", "timestamp(3)")
        }];

        let ddl =
            generate_create_table_ddl(&cols, "items", "", "", &DatabaseType::Mysql, &DatabaseType::Mysql, None, None);

        assert!(ddl.contains("ON UPDATE CURRENT_TIMESTAMP(3)"), "ddl: {ddl}");
        assert!(!ddl.contains("DEFAULT"), "ddl should not emit DEFAULT when none was set: {ddl}");
    }

    #[test]
    fn non_mysql_target_does_not_emit_auto_increment() {
        let cols = vec![db::ColumnInfo {
            is_primary_key: true,
            is_nullable: false,
            extra: Some("auto_increment".to_string()),
            ..test_column("id", "int")
        }];

        let ddl =
            generate_create_table_ddl(&cols, "users", "", "", &DatabaseType::Sqlite, &DatabaseType::Mysql, None, None);

        assert!(!ddl.contains("AUTO_INCREMENT"), "non-mysql target should not emit AUTO_INCREMENT: {ddl}");
    }

    #[test]
    fn postgres_create_table_default_clause_unchanged() {
        let cols = vec![db::ColumnInfo {
            data_type: "integer".to_string(),
            column_default: Some("nextval('public.t_id_seq'::regclass)".to_string()),
            is_primary_key: true,
            is_nullable: false,
            ..test_column("id", "integer")
        }];

        let ddl = generate_create_table_ddl(
            &cols,
            "t",
            "public",
            "public",
            &DatabaseType::Postgres,
            &DatabaseType::Postgres,
            None,
            None,
        );

        assert!(ddl.contains("GENERATED BY DEFAULT AS IDENTITY"), "ddl: {ddl}");
    }

    #[test]
    fn postgres_create_table_preserves_identity_from_column_extra() {
        let cols = vec![db::ColumnInfo {
            data_type: "integer".to_string(),
            extra: Some("generated by default as identity".to_string()),
            is_primary_key: true,
            is_nullable: false,
            ..test_column("id", "integer")
        }];

        let ddl = generate_create_table_ddl(
            &cols,
            "t",
            "public",
            "public",
            &DatabaseType::Postgres,
            &DatabaseType::Postgres,
            None,
            None,
        );

        assert!(ddl.contains("\"id\" integer generated by default as identity NOT NULL"), "ddl: {ddl}");
    }

    #[test]
    fn kingbase_transfer_uses_postgres_compatible_types() {
        assert_eq!(map_column_type("jsonb", &DatabaseType::Postgres, &DatabaseType::Kingbase), "JSONB");
        assert_eq!(map_column_type("bytea", &DatabaseType::Postgres, &DatabaseType::Kingbase), "BYTEA");
        assert_eq!(map_column_type("uuid", &DatabaseType::Postgres, &DatabaseType::Kingbase), "UUID");
        assert_eq!(map_column_type("serial", &DatabaseType::Postgres, &DatabaseType::Kingbase), "SERIAL");
    }

    #[test]
    fn kingbase_create_table_preserves_postgres_defaults() {
        let cols = vec![db::ColumnInfo {
            data_type: "integer".to_string(),
            column_default: Some("nextval('source.items_id_seq'::regclass)".to_string()),
            is_primary_key: true,
            is_nullable: false,
            ..test_column("id", "integer")
        }];

        let ddl = generate_create_table_ddl(
            &cols,
            "items",
            "source",
            "target",
            &DatabaseType::Kingbase,
            &DatabaseType::Postgres,
            None,
            None,
        );

        assert!(ddl.contains("GENERATED BY DEFAULT AS IDENTITY"), "ddl: {ddl}");
    }

    #[test]
    fn kingbase_upsert_uses_on_conflict() {
        let sql = generate_upsert_typed(
            &[String::from("id"), String::from("name")],
            &[Some(String::from("integer")), Some(String::from("text"))],
            &[vec![json!(1), json!("updated")]],
            "items",
            "public",
            &DatabaseType::Kingbase,
            &[String::from("id")],
            None,
        );

        assert!(sql.contains("ON CONFLICT (\"id\") DO UPDATE SET \"name\" = EXCLUDED.\"name\""), "sql: {sql}");
    }

    #[test]
    fn kingbase_reused_ddl_uses_postgres_statement_sanitization() {
        let ddl = r#"CREATE TABLE public.items (id integer PRIMARY KEY);
CREATE INDEX items_name_idx ON public.items (id);"#;

        let statements = transfer_ddl_statements(ddl, &DatabaseType::Kingbase);

        assert_eq!(statements.len(), 1);
        assert!(statements[0].starts_with("CREATE TABLE"));
    }
}