use serde::{Deserialize, Serialize};
use serde_json::Value;
use std::collections::{HashMap, HashSet};
use std::future::Future;
use std::io::{BufWriter, Write};
use std::sync::RwLock;
use std::time::Duration;

use crate::connection::task_client_session_id;
use crate::models::connection::DatabaseType;
use crate::mysql_ddl_normalize::DdlNormalizeOptions;
use crate::object_source_sql::build_export_object_source_sql;
use crate::sql_dialect::{qualified_table_name, uses_single_row_insert_statements};
use crate::transfer::{
    format_ch_array_sql_literal, format_pg_array_sql_literal, is_identity_column_extra,
    is_mysql_generated_column_extra, keyset_pagination_sql_with_identifier_quote, quote_identifier,
    quote_postgres_string_literal, wrap_dameng_identity_insert_sql_for_table,
};
use crate::types::ObjectSourceKind;

static EXPORT_CANCELLED: std::sync::LazyLock<RwLock<HashSet<String>>> =
    std::sync::LazyLock::new(|| RwLock::new(HashSet::new()));

const EXPORT_CANCELLED_ERROR: &str = "Export cancelled";
const EXPORT_CANCEL_POLL_INTERVAL: Duration = Duration::from_millis(50);

pub fn database_export_client_session_id(export_id: &str) -> String {
    task_client_session_id("database-export", export_id)
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct DatabaseExportRequest {
    pub export_id: String,
    pub connection_id: String,
    pub database: String,
    pub schema: String,
    pub file_path: String,
    #[serde(default)]
    pub selected_tables: Vec<String>,
    #[serde(default)]
    pub excluded_tables: Vec<String>,
    pub include_structure: bool,
    pub include_data: bool,
    pub include_objects: bool,
    /// Include a MySQL `CREATE DATABASE IF NOT EXISTS` and `USE` preamble.
    /// The option is intentionally opt-in because it needs CREATE privileges
    /// when importing into a new server.
    #[serde(default)]
    pub include_create_database: bool,
    #[serde(default)]
    pub drop_table_if_exists: bool,
    /// Drop the table-level `AUTO_INCREMENT=N` clause from exported MySQL DDL,
    /// so the script can initialize a fresh database without pinning a sequence
    /// position. No-op for non-MySQL databases. Defaults to `false` (preserve).
    #[serde(default)]
    pub omit_auto_increment: bool,
    #[serde(default)]
    pub fail_on_error: bool,
    #[serde(default)]
    pub snapshot_session_id: Option<String>,
    pub batch_size: usize,
}

#[derive(Debug, Default, PartialEq, Eq)]
struct DatabaseExportObjectCounts {
    tables: usize,
    views: usize,
    sequences: usize,
    extensions: usize,
    procedures: usize,
    functions: usize,
}

fn exports_database_tables(request: &DatabaseExportRequest) -> bool {
    request.include_structure || request.include_data
}

fn exports_database_routines(request: &DatabaseExportRequest) -> bool {
    // Routine export is schema-wide, so an explicit table selection must not
    // add unrelated procedures or functions to either execution or progress.
    request.include_objects && request.selected_tables.is_empty()
}

fn database_export_total_objects(request: &DatabaseExportRequest, counts: &DatabaseExportObjectCounts) -> usize {
    let mut total = 0;
    if exports_database_tables(request) {
        total += counts.tables;
    }
    if request.include_structure {
        total += counts.sequences + counts.extensions;
    }
    if request.include_objects {
        total += counts.views;
    }
    if exports_database_routines(request) {
        total += counts.procedures + counts.functions;
    }
    total
}

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

fn mysql_view_dependencies_sql(database: &str) -> String {
    let database = mysql_sql_string_literal(database);
    format!(
        "SELECT VIEW_NAME, TABLE_NAME FROM information_schema.VIEW_TABLE_USAGE \
         WHERE VIEW_SCHEMA = {database} AND TABLE_SCHEMA = {database} \
         ORDER BY VIEW_NAME, TABLE_NAME"
    )
}

fn mysql_view_dependencies_from_rows(rows: &[Vec<Value>]) -> Vec<(String, String)> {
    rows.iter()
        .filter_map(|row| {
            let view_name = row.first()?.as_str()?.trim();
            let referenced_name = row.get(1)?.as_str()?.trim();
            (!view_name.is_empty() && !referenced_name.is_empty())
                .then(|| (view_name.to_string(), referenced_name.to_string()))
        })
        .collect()
}

async fn list_mysql_export_view_dependencies(
    state: &crate::connection::AppState,
    connection_id: &str,
    database: &str,
) -> Result<Vec<(String, String)>, String> {
    let result = crate::query::execute_sql_statement_with_options(
        state,
        connection_id,
        database,
        &mysql_view_dependencies_sql(database),
        None,
        None,
        crate::query::QueryExecutionOptions { max_rows: Some(usize::MAX), ..Default::default() },
    )
    .await?;
    Ok(mysql_view_dependencies_from_rows(&result.rows))
}

fn sort_export_views_by_dependencies<'a>(
    views: &[&'a crate::types::TableInfo],
    dependencies: &[(String, String)],
) -> Vec<&'a crate::types::TableInfo> {
    let names = views.iter().map(|view| view.name.clone()).collect::<Vec<_>>();
    let sorted_names = crate::transfer::sort_table_names_by_dependencies(&names, dependencies, true);
    let views_by_name = views.iter().map(|view| (view.name.as_str(), *view)).collect::<HashMap<_, _>>();
    sorted_names.iter().filter_map(|name| views_by_name.get(name.as_str()).copied()).collect()
}

fn mysql_database_export_preamble(database: &str, charset: Option<&str>, collation: Option<&str>) -> String {
    let database = quote_identifier(database, &DatabaseType::Mysql);
    let charset = charset.map(str::trim).filter(|value| !value.is_empty());
    let collation = collation.map(str::trim).filter(|value| !value.is_empty());
    let options = match charset {
        Some(charset) => match collation {
            Some(collation) => format!(" CHARACTER SET {charset} COLLATE {collation}"),
            None => format!(" CHARACTER SET {charset}"),
        },
        None => String::new(),
    };
    format!("CREATE DATABASE IF NOT EXISTS {database}{options};\nUSE {database};\n")
}

async fn mysql_database_export_preamble_for_request(
    state: &crate::connection::AppState,
    request: &DatabaseExportRequest,
) -> String {
    let metadata_sql = format!(
        "SELECT DEFAULT_CHARACTER_SET_NAME, DEFAULT_COLLATION_NAME FROM information_schema.SCHEMATA WHERE SCHEMA_NAME = {}",
        mysql_sql_string_literal(&request.database)
    );
    let metadata = crate::query::execute_sql_statement(
        state,
        &request.connection_id,
        &request.database,
        &metadata_sql,
        None,
        None,
    )
    .await
    .ok()
    .and_then(|result| {
        result.rows.first().map(|row| {
            (
                row.first().and_then(Value::as_str).map(str::to_string),
                row.get(1).and_then(Value::as_str).map(str::to_string),
            )
        })
    });

    match metadata {
        Some((charset, collation)) => {
            mysql_database_export_preamble(&request.database, charset.as_deref(), collation.as_deref())
        }
        None => mysql_database_export_preamble(&request.database, None, None),
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct DatabaseBackupSnapshot {
    pub session_id: String,
    pub schemas: Vec<String>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct ExportProgress {
    pub export_id: String,
    pub current_object: String,
    pub object_index: usize,
    pub total_objects: usize,
    pub rows_exported: u64,
    pub total_rows: Option<u64>,
    pub status: ExportStatus,
    pub error: Option<String>,
    /// True while listing schema / prefetching table metadata — before objects are written.
    #[serde(default)]
    pub preparing: bool,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum ExportStatus {
    Running,
    Writing,
    Done,
    Error,
    Cancelled,
}

pub const DATABASE_EXPORT_ROW_LIMIT: usize = 10_000;
pub const DATABASE_EXPORT_PAGE_SIZE: usize = 500;
pub const DATABASE_EXPORT_INSERT_BATCH_SIZE: usize = 100;
pub const DATABASE_EXPORT_TARGET_STATEMENT_BYTES: usize = 512 * 1024;

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

#[derive(Debug, Clone, PartialEq, Eq)]
struct PostgresExportExtension {
    name: String,
    schema: String,
}

#[derive(Debug, Default)]
struct PostgresExtensionMembers {
    relation_names: HashSet<String>,
    function_keys: HashSet<(String, String)>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct ExportedTableSql {
    pub display_name: String,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub database_type: Option<DatabaseType>,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub identifier_quote: Option<String>,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub schema: Option<String>,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub table_name: Option<String>,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub qualified_table_name: Option<String>,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub ddl: Option<String>,
    #[serde(default)]
    pub columns: Vec<String>,
    #[serde(default)]
    pub column_types: Vec<Option<String>>,
    #[serde(default)]
    pub column_extras: Vec<Option<String>>,
    #[serde(default)]
    pub rows: Vec<Vec<Value>>,
    #[serde(default)]
    pub truncated: bool,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct BuildExportInsertStatementsOptions {
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub database_type: Option<DatabaseType>,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub identifier_quote: Option<String>,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub schema: Option<String>,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub table_name: Option<String>,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub qualified_table_name: Option<String>,
    #[serde(default)]
    pub columns: Vec<String>,
    #[serde(default)]
    pub column_types: Vec<Option<String>>,
    #[serde(default)]
    pub column_extras: Vec<Option<String>>,
    #[serde(default)]
    pub rows: Vec<Vec<Value>>,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub batch_size: Option<usize>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct BuildExportSqlInsertOptions {
    #[serde(flatten)]
    pub insert: BuildExportInsertStatementsOptions,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct BuildDatabaseSqlExportOptions {
    pub database_name: String,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub exported_at: Option<String>,
    #[serde(default)]
    pub tables: Vec<ExportedTableSql>,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub row_limit_per_table: Option<usize>,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub insert_batch_size: Option<usize>,
    /// Optional connection info for FK-aware table ordering.
    /// When set, the caller should sort tables by dependency before passing them
    /// to `build_database_sql_export`.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub connection_id: Option<String>,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub database: Option<String>,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub schema: Option<String>,
    /// Drop the table-level `AUTO_INCREMENT=N` clause from exported MySQL DDL.
    /// Defaults to `false` (preserve). See `DatabaseExportRequest::omit_auto_increment`.
    #[serde(default)]
    pub omit_auto_increment: bool,
}

pub fn format_export_sql_literal(value: &Value) -> String {
    format_export_sql_literal_for_database(value, None)
}

fn format_export_sql_literal_for_database(value: &Value, database_type: Option<DatabaseType>) -> String {
    if value.is_null() {
        return "NULL".to_string();
    }
    if let Some(number) = value.as_number() {
        return number.to_string();
    }
    if let Some(value) = value.as_bool() {
        if matches!(database_type, Some(DatabaseType::Dameng) | Some(DatabaseType::SqlServer)) {
            return if value { "1" } else { "0" }.to_string();
        }
        return if value { "TRUE" } else { "FALSE" }.to_string();
    }
    if let Some(arr) = value.as_array() {
        return format_pg_array_sql_literal(arr);
    }
    let text = value.as_str().map_or_else(|| value.to_string(), ToString::to_string);
    quote_export_sql_string_for_database(&text, database_type)
}

fn format_export_sql_literal_typed(
    value: &Value,
    database_type: Option<DatabaseType>,
    column_type: Option<&str>,
    sqlserver_unicode_string: bool,
) -> String {
    if is_postgres_json_export_column(database_type, column_type) {
        return format_postgres_json_export_literal(value);
    }
    if is_postgres_vector_export_column(database_type, column_type) {
        return format_postgres_vector_export_literal(value);
    }
    if matches!(database_type, Some(DatabaseType::Mysql)) && column_type.is_some_and(is_mysql_bit_type) {
        return format_mysql_bit_literal(value);
    }
    if let Some(literal) = format_mysql_spatial_export_literal(value, database_type, column_type) {
        return literal;
    }
    if is_mysql_compatible_export_literal_target(database_type) {
        if column_type.is_some_and(is_mysql_binary_export_type) {
            if let Some(literal) = format_mysql_binary_export_literal(value) {
                return literal;
            }
        }
        if column_type.is_some_and(is_export_numeric_type) {
            if let Some(literal) = format_export_numeric_literal(value) {
                return literal;
            }
        }
    }
    if let Some(arr) = value.as_array() {
        if matches!(database_type, Some(DatabaseType::ClickHouse) | Some(DatabaseType::Databend)) {
            return format_ch_array_sql_literal(arr);
        }
    }
    if let Some(literal) = format_oracle_export_temporal_literal(value, database_type, column_type) {
        return literal;
    }
    if let Some(literal) = format_export_temporal_literal(value, database_type, column_type) {
        return literal;
    }
    if sqlserver_unicode_string {
        if let Some(text) = value.as_str() {
            return format!("N{}", quote_export_sql_string(text));
        }
    }
    format_export_sql_literal_for_database(value, database_type)
}

fn format_postgres_json_export_literal(value: &Value) -> String {
    if value.is_null() {
        return "NULL".to_string();
    }
    let text = value.as_str().map_or_else(|| value.to_string(), ToString::to_string);
    // PostgreSQL standard strings keep backslashes literal; JSON text needs its
    // own escape sequences, so only SQL-escape the surrounding string delimiter.
    quote_postgres_string_literal(&text)
}

fn format_postgres_vector_export_literal(value: &Value) -> String {
    if value.is_null() {
        return "NULL".to_string();
    }
    let text = match value {
        // pgvector vector/halfvec are scalar extension types whose importable
        // literal grammar uses square brackets, unlike PostgreSQL arrays.
        Value::Array(arr) => format_postgres_vector_export_text(arr),
        Value::String(text) => text.to_string(),
        _ => value.to_string(),
    };
    quote_postgres_string_literal(&text)
}

fn format_postgres_vector_export_text(arr: &[Value]) -> String {
    let elements = arr.iter().map(format_postgres_vector_export_element).collect::<Vec<_>>();
    format!("[{}]", elements.join(","))
}

fn format_postgres_vector_export_element(value: &Value) -> String {
    match value {
        Value::String(text) => text.trim().to_string(),
        Value::Number(number) => number.to_string(),
        Value::Bool(value) => value.to_string(),
        Value::Null => "NULL".to_string(),
        _ => value.to_string(),
    }
}

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

fn is_sqlserver_unicode_export_type(column_type: &str) -> bool {
    let base = column_type.trim().split(|ch: char| ch == '(' || ch.is_whitespace()).next().unwrap_or("");
    ["nchar", "nvarchar", "ntext", "sysname"].iter().any(|candidate| base.eq_ignore_ascii_case(candidate))
}

fn quote_export_sql_string_for_database(text: &str, database_type: Option<DatabaseType>) -> String {
    match database_type {
        Some(DatabaseType::Dameng) => quote_dameng_export_sql_string(text),
        Some(DatabaseType::Postgres) => quote_postgres_string_literal(text),
        database_type if is_mysql_compatible_export_literal_target(database_type) => {
            quote_mysql_compatible_export_sql_string(text)
        }
        _ => quote_export_sql_string(text),
    }
}

fn quote_dameng_export_sql_string(text: &str) -> String {
    if !text.contains('\0') {
        return quote_export_sql_string(text);
    }

    let mut parts = Vec::new();
    for (index, segment) in text.split('\0').enumerate() {
        if index > 0 {
            parts.push("CHR(0)".to_string());
        }
        if !segment.is_empty() {
            parts.push(quote_export_sql_string(segment));
        }
    }
    parts.join(" || ")
}

fn quote_mysql_compatible_export_sql_string(text: &str) -> String {
    format!("'{}'", escape_mysql_compatible_export_sql_string(text))
}

fn escape_mysql_compatible_export_sql_string(text: &str) -> String {
    let mut escaped = String::with_capacity(text.len());
    for ch in text.chars() {
        match ch {
            // MySQL-family dumps should keep control characters out of the
            // physical script layout while relying on the dialect's escapes.
            '\0' => escaped.push_str("\\0"),
            '\x08' => escaped.push_str("\\b"),
            '\n' => escaped.push_str("\\n"),
            '\r' => escaped.push_str("\\r"),
            '\t' => escaped.push_str("\\t"),
            '\x0c' => escaped.push_str("\\f"),
            '\x1a' => escaped.push_str("\\Z"),
            '\\' => escaped.push_str("\\\\"),
            '\'' => escaped.push_str("''"),
            _ => escaped.push(ch),
        }
    }
    escaped
}

fn is_mysql_compatible_export_literal_target(database_type: Option<DatabaseType>) -> bool {
    matches!(
        database_type,
        Some(DatabaseType::Mysql | DatabaseType::Doris | DatabaseType::StarRocks | DatabaseType::Goldendb)
    )
}

fn format_oracle_export_temporal_literal(
    value: &Value,
    database_type: Option<DatabaseType>,
    column_type: Option<&str>,
) -> Option<String> {
    if !matches!(database_type, Some(DatabaseType::Oracle | DatabaseType::OceanbaseOracle)) {
        return None;
    }
    let column_type = column_type?;
    let lower = column_type.trim().trim_matches('"').to_ascii_lowercase();
    let base = lower.split(['(', ' ', '\t', '\n']).next().unwrap_or("");
    let kind = match base {
        "timestampdty" => ExportTemporalKind::DateTime,
        "timestamptz_dty" => ExportTemporalKind::DateTimeWithTimeZone,
        _ => export_temporal_column_kind(database_type, column_type)?,
    };
    let parts = parse_export_date_parts(value.as_str()?)?;
    if base == "date" {
        return Some(format_oracle_export_date_parts_literal(&parts));
    }

    let fraction = parts.fraction.as_deref().unwrap_or_default();
    let datetime = format!("{} {}{fraction}", parts.date, parts.time);
    let mask = if fraction.is_empty() { "YYYY-MM-DD HH24:MI:SS" } else { "YYYY-MM-DD HH24:MI:SS.FF" };
    if kind == ExportTemporalKind::DateTimeWithTimeZone && !parts.zone.is_empty() {
        let zone = normalize_export_timezone(&parts.zone);
        return Some(format!("TO_TIMESTAMP_TZ('{datetime} {zone}', '{mask} TZH:TZM')"));
    }
    Some(format!("TO_TIMESTAMP('{datetime}', '{mask}')"))
}

fn format_oracle_export_date_parts_literal(parts: &ExportRfc3339Parts) -> String {
    if export_temporal_parts_are_midnight(parts) {
        format!("DATE '{}'", parts.date)
    } else {
        format!("TO_DATE('{} {}', 'YYYY-MM-DD HH24:MI:SS')", parts.date, parts.time)
    }
}

fn export_temporal_parts_are_midnight(parts: &ExportRfc3339Parts) -> bool {
    parts.time == "00:00:00"
        && parts
            .fraction
            .as_deref()
            .map(|fraction| fraction.trim_start_matches('.').chars().all(|ch| ch == '0'))
            .unwrap_or(true)
}

fn format_export_temporal_literal(
    value: &Value,
    database_type: Option<DatabaseType>,
    column_type: Option<&str>,
) -> Option<String> {
    let text = value.as_str()?;
    let column_type = column_type?;
    if database_type == Some(DatabaseType::SqlServer) {
        return crate::sqlserver_temporal::normalize_sqlserver_temporal_literal(text, Some(column_type))
            .map(|text| quote_export_sql_string(&text));
    }
    let kind = export_temporal_column_kind(database_type, column_type)?;
    format_rfc3339_export_temporal_text(text, kind, database_type).map(|text| quote_export_sql_string(&text))
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum ExportTemporalKind {
    Date,
    Time,
    DateTime,
    DateTimeWithTimeZone,
}

fn export_temporal_column_kind(database_type: Option<DatabaseType>, column_type: &str) -> Option<ExportTemporalKind> {
    let lower = column_type.trim().trim_matches('"').to_ascii_lowercase();
    let base = lower.split(['(', ' ', '\t', '\n']).next().unwrap_or("");
    match base {
        "date" if matches!(database_type, Some(DatabaseType::Oracle | DatabaseType::OceanbaseOracle)) => {
            Some(ExportTemporalKind::DateTime)
        }
        "date" => Some(ExportTemporalKind::Date),
        "time" => Some(ExportTemporalKind::Time),
        "datetime" | "datetime2" | "smalldatetime" | "datetime64" => Some(ExportTemporalKind::DateTime),
        "datetimeoffset" | "timestamptz" => Some(ExportTemporalKind::DateTimeWithTimeZone),
        _ if lower.starts_with("timestamp")
            && (lower.contains("with time zone") || lower.contains("with local time zone")) =>
        {
            Some(ExportTemporalKind::DateTimeWithTimeZone)
        }
        _ if lower.starts_with("timestamp") => Some(ExportTemporalKind::DateTime),
        _ => None,
    }
}

fn format_rfc3339_export_temporal_text(
    text: &str,
    kind: ExportTemporalKind,
    database_type: Option<DatabaseType>,
) -> Option<String> {
    let parts = parse_export_rfc3339_parts(text)?;
    let fraction = normalize_export_fraction(parts.fraction.as_deref(), database_type);
    match kind {
        ExportTemporalKind::Date => Some(parts.date),
        ExportTemporalKind::Time => Some(format!("{}{fraction}", parts.time)),
        ExportTemporalKind::DateTime => Some(format!("{} {}{fraction}", parts.date, parts.time)),
        ExportTemporalKind::DateTimeWithTimeZone => {
            Some(format!("{} {}{fraction}{}", parts.date, parts.time, normalize_export_timezone(&parts.zone)))
        }
    }
}

struct ExportRfc3339Parts {
    date: String,
    time: String,
    fraction: Option<String>,
    zone: String,
}

fn parse_export_date_parts(text: &str) -> Option<ExportRfc3339Parts> {
    parse_export_rfc3339_parts(text).or_else(|| parse_export_local_temporal_parts(text))
}

fn parse_export_local_temporal_parts(text: &str) -> Option<ExportRfc3339Parts> {
    let bytes = text.as_bytes();
    if bytes.len() < 10 || bytes.get(4) != Some(&b'-') || bytes.get(7) != Some(&b'-') {
        return None;
    }
    let date = &text[0..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(ExportRfc3339Parts {
            date: date.to_string(),
            time: "00:00:00".to_string(),
            fraction: None,
            zone: String::new(),
        });
    }
    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 = &text[11..19];
    if !time.as_bytes().iter().enumerate().all(|(index, byte)| matches!(index, 2 | 5) || byte.is_ascii_digit()) {
        return None;
    }
    let rest = &text[19..];
    let fraction = if let Some(rest) = rest.strip_prefix('.') {
        let digit_count = rest.chars().take_while(|ch| ch.is_ascii_digit()).count();
        if digit_count == 0 || digit_count > 9 || digit_count != rest.len() {
            return None;
        }
        Some(format!(".{}", &rest[..digit_count]))
    } else if rest.is_empty() {
        None
    } else {
        return None;
    };
    Some(ExportRfc3339Parts { date: date.to_string(), time: time.to_string(), fraction, zone: String::new() })
}

fn parse_export_rfc3339_parts(text: &str) -> Option<ExportRfc3339Parts> {
    let bytes = text.as_bytes();
    if bytes.len() < 20 || bytes.get(4) != Some(&b'-') || bytes.get(7) != Some(&b'-') {
        return None;
    }
    let separator = *bytes.get(10)?;
    if separator != b'T' && separator != b' ' {
        return None;
    }
    if bytes.get(13) != Some(&b':') || bytes.get(16) != Some(&b':') {
        return None;
    }
    let date = &text[0..10];
    let time = &text[11..19];
    if !date.as_bytes().iter().enumerate().all(|(index, byte)| matches!(index, 4 | 7) || byte.is_ascii_digit())
        || !time.as_bytes().iter().enumerate().all(|(index, byte)| matches!(index, 2 | 5) || byte.is_ascii_digit())
    {
        return None;
    }
    let rest = &text[19..];
    let (fraction, zone) = if let Some(rest) = rest.strip_prefix('.') {
        let digit_count = rest.chars().take_while(|ch| ch.is_ascii_digit()).count();
        if digit_count == 0 || digit_count > 9 {
            return None;
        }
        (Some(format!(".{}", &rest[..digit_count])), &rest[digit_count..])
    } else {
        (None, rest)
    };
    if zone.eq_ignore_ascii_case("z") || is_export_timezone_offset(zone) {
        Some(ExportRfc3339Parts { date: date.to_string(), time: time.to_string(), fraction, zone: zone.to_string() })
    } else {
        None
    }
}

fn normalize_export_fraction(fraction: Option<&str>, database_type: Option<DatabaseType>) -> String {
    match fraction {
        Some(fraction) if database_type == Some(DatabaseType::Mysql) && fraction.len() > 7 => fraction[..7].to_string(),
        Some(fraction) => fraction.to_string(),
        None => String::new(),
    }
}

fn normalize_export_timezone(zone: &str) -> String {
    if zone.eq_ignore_ascii_case("z") {
        "+00:00".to_string()
    } else {
        zone.to_string()
    }
}

fn is_export_timezone_offset(value: &str) -> bool {
    let bytes = value.as_bytes();
    bytes.len() == 6
        && matches!(bytes[0], b'+' | b'-')
        && bytes[3] == b':'
        && bytes[1].is_ascii_digit()
        && bytes[2].is_ascii_digit()
        && bytes[4].is_ascii_digit()
        && bytes[5].is_ascii_digit()
}

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 format_mysql_bit_literal(value: &Value) -> String {
    match value {
        Value::Null => "NULL".to_string(),
        Value::Bool(value) => {
            if *value {
                "b'1'".to_string()
            } else {
                "b'0'".to_string()
            }
        }
        Value::Number(value) => {
            let s = value.to_string();
            if s == "0" || s == "1" {
                format!("b'{s}'")
            } else {
                s
            }
        }
        Value::String(value) => {
            let trimmed = value.trim();
            if trimmed.eq_ignore_ascii_case("true") {
                return "b'1'".to_string();
            }
            if trimmed.eq_ignore_ascii_case("false") {
                return "b'0'".to_string();
            }
            if trimmed == "0" || trimmed == "1" {
                return format!("b'{trimmed}'");
            }
            if !trimmed.is_empty() && trimmed.bytes().all(|byte| byte == b'0' || byte == b'1') {
                return format!("b'{trimmed}'");
            }
            format!("b'{}'", escape_mysql_compatible_export_sql_string(value))
        }
        other => format_export_sql_literal(other),
    }
}

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

pub(crate) fn is_mysql_spatial_export_type(column_type: &str) -> bool {
    let base = column_type
        .trim()
        .to_ascii_lowercase()
        .split(['(', ':', ' ', '\t', '\n'])
        .next()
        .unwrap_or("")
        .trim()
        .to_string();
    matches!(
        base.as_str(),
        "geometry"
            | "point"
            | "linestring"
            | "polygon"
            | "multipoint"
            | "multilinestring"
            | "multipolygon"
            | "geometrycollection"
            | "geomcollection"
    )
}

/// Database exports encode MySQL spatial cells as `DBX_WKB:<srid>:<hex>` while
/// reading them. Keeping this marker internal lets the normal JSON row shape
/// and all non-export query paths continue to expose readable WKT values.
pub(crate) fn format_mysql_spatial_export_literal(
    value: &Value,
    database_type: Option<DatabaseType>,
    column_type: Option<&str>,
) -> Option<String> {
    if database_type != Some(DatabaseType::Mysql) || !column_type.is_some_and(is_mysql_spatial_export_type) {
        return None;
    }
    let Value::String(value) = value else {
        return value.is_null().then(|| "NULL".to_string());
    };
    let marker = value.strip_prefix("DBX_WKB:")?;
    let (srid, hex) = marker.split_once(':')?;
    if srid.is_empty()
        || !srid.as_bytes().iter().all(u8::is_ascii_digit)
        || hex.is_empty()
        || hex.len() % 2 != 0
        || !hex.as_bytes().iter().all(u8::is_ascii_hexdigit)
    {
        return None;
    }
    let wkb = decode_mysql_spatial_export_wkb(hex)?;
    crate::db::wkb::decode_wkb_geometry(&wkb)?;
    let srid = srid.parse::<u32>().ok()?;
    Some(if srid == 0 { format!("ST_GeomFromWKB(0x{hex})") } else { format!("ST_GeomFromWKB(0x{hex}, {srid})") })
}

fn decode_mysql_spatial_export_wkb(hex: &str) -> Option<Vec<u8>> {
    fn nibble(byte: u8) -> Option<u8> {
        match byte {
            b'0'..=b'9' => Some(byte - b'0'),
            b'a'..=b'f' => Some(byte - b'a' + 10),
            b'A'..=b'F' => Some(byte - b'A' + 10),
            _ => None,
        }
    }

    hex.as_bytes().chunks_exact(2).map(|pair| Some((nibble(pair[0])? << 4) | nibble(pair[1])?)).collect()
}

fn format_mysql_binary_export_literal(value: &Value) -> Option<String> {
    match value {
        Value::Null => Some("NULL".to_string()),
        Value::String(text) => format_mysql_binary_export_literal_text(text),
        _ => None,
    }
}

fn format_mysql_binary_export_literal_text(text: &str) -> Option<String> {
    let trimmed = text.trim();
    let hex = trimmed.strip_prefix("0x").or_else(|| trimmed.strip_prefix("0X"))?;
    if hex.chars().all(|ch| ch.is_ascii_hexdigit()) {
        // DBX exposes MySQL binary cells as 0x-prefixed hex text. Keep it as a
        // MySQL hex literal so exported INSERT statements round-trip bytes.
        Some(if hex.is_empty() { "X''".to_string() } else { format!("0x{hex}") })
    } else {
        None
    }
}

fn is_export_numeric_type(column_type: &str) -> bool {
    let lower = column_type.to_ascii_lowercase();
    [
        "int",
        "integer",
        "bigint",
        "smallint",
        "tinyint",
        "mediumint",
        "serial",
        "number",
        "numeric",
        "decimal",
        "dec",
        "fixed",
        "float",
        "double",
        "real",
    ]
    .iter()
    .any(|part| lower.split(|ch: char| !ch.is_ascii_alphanumeric()).any(|token| token == *part))
}

fn format_export_numeric_literal(value: &Value) -> Option<String> {
    match value {
        Value::Number(number) => Some(number.to_string()),
        Value::String(text) if is_export_numeric_literal(text) => Some(text.to_string()),
        _ => None,
    }
}

fn is_export_numeric_literal(text: &str) -> bool {
    if text.trim() != text || text.is_empty() {
        return false;
    }
    text.parse::<f64>().is_ok_and(f64::is_finite)
        && text.chars().all(|ch| ch.is_ascii_digit() || matches!(ch, '+' | '-' | '.' | 'e' | 'E'))
        && text.chars().any(|ch| ch.is_ascii_digit())
}

pub fn build_export_insert_statements(options: BuildExportInsertStatementsOptions) -> Result<Vec<String>, String> {
    if options.columns.is_empty() || options.rows.is_empty() {
        return Ok(Vec::new());
    }

    let table = export_qualified_table_name(
        options.database_type,
        options.schema.as_deref(),
        options.table_name.as_deref(),
        options.qualified_table_name.as_deref(),
        options.identifier_quote.as_deref(),
    )?;
    let insert_columns = options
        .columns
        .iter()
        .enumerate()
        .filter_map(|(index, column)| {
            let column_type = options.column_types.get(index).and_then(|value| value.as_deref());
            is_export_insert_column(
                options.database_type,
                column,
                column_type,
                options.column_extras.get(index).and_then(|value| value.as_deref()),
            )
            .then(|| {
                let sqlserver_unicode_string = options.database_type == Some(DatabaseType::SqlServer)
                    && column_type.is_some_and(is_sqlserver_unicode_export_type);
                (index, column, sqlserver_unicode_string)
            })
        })
        .collect::<Vec<_>>();
    if insert_columns.is_empty() {
        return Ok(Vec::new());
    }
    let batch_size = if options.database_type.is_some_and(uses_single_row_insert_statements) {
        1
    } else {
        let requested = options.batch_size.unwrap_or(DATABASE_EXPORT_INSERT_BATCH_SIZE).max(1);
        if options.database_type == Some(DatabaseType::SqlServer) {
            requested.min(1000)
        } else {
            requested
        }
    };
    let columns = insert_columns
        .iter()
        .map(|(_, column, _)| {
            crate::sql_dialect::quote_table_data_identifier(
                options.database_type,
                column,
                options.identifier_quote.as_deref(),
            )
        })
        .collect::<Vec<_>>()
        .join(", ");
    let mut statements = Vec::new();
    let needs_dameng_identity_insert = options.database_type == Some(DatabaseType::Dameng)
        && insert_columns.iter().any(|(index, _, _)| {
            is_identity_column_extra(options.column_extras.get(*index).and_then(|value| value.as_deref()))
        });

    let statement_prefix = format!("INSERT INTO {table} ({columns}) VALUES ");
    let statement_overhead_bytes = export_sql_statement_bytes(options.database_type, &statement_prefix) + 1;
    let target_statement_bytes = DATABASE_EXPORT_TARGET_STATEMENT_BYTES;
    let separator_bytes = export_sql_statement_bytes(options.database_type, ", ");
    let mut current_values = String::new();
    let mut current_values_bytes = 0usize;
    let mut current_row_count = 0usize;

    let flush_values =
        |statements: &mut Vec<String>, values: &mut String, values_bytes: &mut usize, row_count: &mut usize| {
            if *row_count == 0 {
                return;
            }
            let mut insert_sql = String::with_capacity(statement_prefix.len() + values.len() + 1);
            insert_sql.push_str(&statement_prefix);
            insert_sql.push_str(values);
            insert_sql.push(';');
            if needs_dameng_identity_insert {
                statements.push(wrap_dameng_identity_insert_sql_for_table(&insert_sql, &table));
            } else {
                statements.push(insert_sql);
            }
            values.clear();
            *values_bytes = 0;
            *row_count = 0;
        };

    for row in options.rows {
        let mut rendered_row = String::with_capacity(insert_columns.len().saturating_mul(16).saturating_add(2));
        rendered_row.push('(');
        for (column_index, (index, _, sqlserver_unicode_string)) in insert_columns.iter().enumerate() {
            if column_index > 0 {
                rendered_row.push_str(", ");
            }
            let value = row.get(*index).unwrap_or(&Value::Null);
            rendered_row.push_str(&format_export_sql_literal_typed(
                value,
                options.database_type,
                options.column_types.get(*index).and_then(|value| value.as_deref()),
                *sqlserver_unicode_string,
            ));
        }
        rendered_row.push(')');
        let rendered_row_bytes = export_sql_statement_bytes(options.database_type, &rendered_row);
        let candidate_bytes = statement_overhead_bytes
            + current_values_bytes
            + if current_row_count == 0 { 0 } else { separator_bytes }
            + rendered_row_bytes;

        if current_row_count > 0 && (current_row_count >= batch_size || candidate_bytes > target_statement_bytes) {
            flush_values(&mut statements, &mut current_values, &mut current_values_bytes, &mut current_row_count);
        }
        if current_row_count > 0 {
            current_values.push_str(", ");
            current_values_bytes += separator_bytes;
        }
        current_values.push_str(&rendered_row);
        current_values_bytes += rendered_row_bytes;
        current_row_count += 1;
    }
    flush_values(&mut statements, &mut current_values, &mut current_values_bytes, &mut current_row_count);

    Ok(statements)
}

fn export_sql_statement_bytes(database_type: Option<DatabaseType>, text: &str) -> usize {
    if database_type == Some(DatabaseType::SqlServer) {
        text.encode_utf16().count() * 2
    } else {
        text.len()
    }
}

pub(crate) fn is_internal_export_column(database_type: Option<DatabaseType>, column: &str) -> bool {
    // Oracle-compatible ROWID is injected only to identify editable rows. It
    // is not a physical table column and must never propagate into exports.
    crate::sql_dialect::uses_oracle_row_id(database_type)
        && column.eq_ignore_ascii_case(crate::sql_dialect::DBX_ROWID_COLUMN)
}

fn is_postgres_tsvector_export_column(database_type: Option<DatabaseType>, column_type: Option<&str>) -> bool {
    database_type == Some(DatabaseType::Postgres)
        && column_type
            .map(|column_type| {
                let normalized = column_type.trim().trim_matches('"').to_ascii_lowercase();
                normalized == "tsvector" || normalized.ends_with(".tsvector")
            })
            .unwrap_or(false)
}

fn is_export_insert_column(
    database_type: Option<DatabaseType>,
    column: &str,
    column_type: Option<&str>,
    column_extra: Option<&str>,
) -> bool {
    !is_internal_export_column(database_type, column)
        && !is_postgres_tsvector_export_column(database_type, column_type)
        && (database_type != Some(DatabaseType::Mysql) || !is_mysql_generated_column_extra(column_extra))
}

fn is_postgres_json_export_column(database_type: Option<DatabaseType>, column_type: Option<&str>) -> bool {
    database_type == Some(DatabaseType::Postgres)
        && column_type
            .map(|column_type| {
                let normalized = column_type.trim().trim_matches('"').to_ascii_lowercase();
                matches!(normalized.as_str(), "json" | "jsonb")
                    || normalized.ends_with(".json")
                    || normalized.ends_with(".jsonb")
            })
            .unwrap_or(false)
}

fn is_postgres_vector_export_column(database_type: Option<DatabaseType>, column_type: Option<&str>) -> bool {
    database_type == Some(DatabaseType::Postgres)
        && column_type
            .map(|column_type| {
                let normalized = column_type.trim().trim_matches('"').to_ascii_lowercase();
                let base = normalized.split(['(', ' ', '\t', '\n']).next().unwrap_or("").trim_matches('"');
                matches!(base, "vector" | "halfvec") || base.ends_with(".vector") || base.ends_with(".halfvec")
            })
            .unwrap_or(false)
}

pub fn build_export_sql_insert(options: BuildExportSqlInsertOptions) -> Result<String, String> {
    build_export_insert_statements(options.insert).map(|statements| statements.join("\n"))
}

pub fn build_database_sql_export(options: BuildDatabaseSqlExportOptions) -> Result<String, String> {
    let exported_at = options.exported_at.unwrap_or_else(|| chrono::Utc::now().to_rfc3339());
    let row_limit = options.row_limit_per_table.unwrap_or(DATABASE_EXPORT_ROW_LIMIT);
    let insert_batch_size = options.insert_batch_size.unwrap_or(DATABASE_EXPORT_INSERT_BATCH_SIZE);
    let mut lines = vec![
        "-- DBX database export".to_string(),
        format!("-- Database: {}", options.database_name),
        format!("-- Exported at: {exported_at}"),
        format!("-- Row limit per table: {row_limit}"),
        String::new(),
    ];

    for table in options.tables {
        if let Some(ddl) = table.ddl.as_ref().map(|ddl| ddl.trim()).filter(|ddl| !ddl.is_empty()) {
            let ddl = format_export_table_ddl(
                ddl,
                table.database_type,
                DdlNormalizeOptions { omit_auto_increment: options.omit_auto_increment },
            );
            lines.push(format!("-- Structure for {}", table.display_name));
            lines.push(ddl);
            lines.push(String::new());
        }

        lines.push(format!("-- Data for {}", table.display_name));
        if table.truncated {
            lines.push(format!("-- Exported rows: {} (truncated at {row_limit})", table.rows.len()));
        } else {
            lines.push(format!("-- Exported rows: {}", table.rows.len()));
        }

        let inserts = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: table.database_type,
            identifier_quote: table.identifier_quote.clone(),
            schema: table.schema,
            table_name: table.table_name,
            qualified_table_name: table.qualified_table_name,
            columns: table.columns,
            column_types: table.column_types,
            column_extras: table.column_extras,
            rows: table.rows,
            batch_size: Some(insert_batch_size),
        })?;
        if inserts.is_empty() {
            lines.push("-- No rows".to_string());
        } else {
            lines.extend(inserts);
        }
        lines.push(String::new());
    }

    Ok(lines.join("\n"))
}

fn export_qualified_table_name(
    database_type: Option<DatabaseType>,
    schema: Option<&str>,
    table_name: Option<&str>,
    qualified_name: Option<&str>,
    identifier_quote: Option<&str>,
) -> Result<String, String> {
    if let Some(name) = qualified_name.filter(|name| !name.trim().is_empty()) {
        return Ok(name.to_string());
    }
    let table_name = table_name
        .filter(|name| !name.trim().is_empty())
        .ok_or_else(|| "tableName is required when qualifiedTableName is not provided".to_string())?;
    if crate::sql_dialect::uses_connection_identifier_quote(database_type, identifier_quote) {
        return Ok(crate::sql_dialect::table_data_qualified_table_name(
            database_type,
            schema,
            table_name,
            identifier_quote,
        ));
    }
    Ok(qualified_table_name(database_type, schema, table_name))
}

fn normalize_export_table_ddl(
    ddl: &str,
    database_type: Option<DatabaseType>,
    opts: crate::mysql_ddl_normalize::DdlNormalizeOptions,
) -> String {
    if database_type != Some(DatabaseType::Mysql) {
        return ddl.to_string();
    }

    crate::mysql_ddl_normalize::normalize_mysql_export_ddl(ddl, opts)
}

fn format_export_table_ddl(ddl: &str, database_type: Option<DatabaseType>, opts: DdlNormalizeOptions) -> String {
    let ddl = normalize_export_table_ddl(ddl, database_type, opts);
    let ddl = ddl.trim().trim_end_matches(';').trim_end();
    format!("{ddl};")
}

fn split_postgres_export_table_triggers(ddl: &str, database_type: DatabaseType) -> (String, Vec<String>) {
    if database_type != DatabaseType::Postgres {
        return (ddl.to_string(), Vec::new());
    }

    let mut table_statements = Vec::new();
    let mut trigger_statements = Vec::new();
    for range in crate::db::ddl_scan::top_level_statement_ranges(ddl) {
        let statement = ddl[range].trim();
        if statement.is_empty() {
            continue;
        }
        let mut words = statement.split_ascii_whitespace().take(3).map(str::to_ascii_uppercase);
        let first = words.next();
        let second = words.next();
        let third = words.next();
        if first.as_deref() == Some("CREATE")
            && (second.as_deref() == Some("TRIGGER")
                || (second.as_deref() == Some("CONSTRAINT") && third.as_deref() == Some("TRIGGER")))
        {
            trigger_statements.push(statement.to_string());
        } else {
            table_statements.push(statement.to_string());
        }
    }
    (table_statements.join("\n"), trigger_statements)
}

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

fn generate_postgres_sequence_create_ddl(sequence: &PostgresExportSequence, 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_sequence_owner_ddl(sequence: &PostgresExportSequence, schema: &str) -> Option<String> {
    let owner_table = sequence.owner_table.as_deref()?;
    let owner_column = sequence.owner_column.as_deref()?;
    Some(format!(
        "ALTER SEQUENCE {} OWNED BY {}.{}",
        postgres_sequence_qualified_name(schema, &sequence.name),
        crate::transfer::qualified_table(owner_table, schema, &DatabaseType::Postgres, None),
        quote_identifier(owner_column, &DatabaseType::Postgres)
    ))
}

fn generate_postgres_sequence_setval_sql(sequence: &PostgresExportSequence, schema: &str) -> Option<String> {
    let last_value = sequence.last_value.as_deref()?.trim();
    if last_value.is_empty() {
        return None;
    }

    let sequence_literal = quote_postgres_string_literal(&postgres_sequence_qualified_name(schema, &sequence.name));
    match (sequence.owner_table.as_deref(), sequence.owner_column.as_deref()) {
        (Some(owner_table), Some(owner_column)) => {
            let owner_table = crate::transfer::qualified_table(owner_table, schema, &DatabaseType::Postgres, None);
            let owner_column = quote_identifier(owner_column, &DatabaseType::Postgres);
            Some(format!(
                "SELECT setval({sequence_literal}, GREATEST(COALESCE(MAX({owner_column}), {last_value}), {last_value}), true) FROM {owner_table}"
            ))
        }
        _ => Some(format!("SELECT setval({sequence_literal}, {last_value}, true)")),
    }
}

fn generate_postgres_extension_ddl(extension: &PostgresExportExtension) -> String {
    // Match pg_dump: omit VERSION so the target installation selects its
    // default compatible version, while preserving the source schema.
    format!(
        "CREATE EXTENSION IF NOT EXISTS {} WITH SCHEMA {};",
        quote_identifier(&extension.name, &DatabaseType::Postgres),
        quote_identifier(&extension.schema, &DatabaseType::Postgres)
    )
}

async fn list_postgres_extension_members(
    state: &crate::connection::AppState,
    pool_key: &str,
    schema: &str,
) -> Result<PostgresExtensionMembers, String> {
    let pool = {
        let connections = state.connections.read().await;
        match connections.get(pool_key) {
            Some(crate::connection::PoolKind::Postgres(pool)) => pool.clone(),
            _ => return Ok(PostgresExtensionMembers::default()),
        }
    };
    let mut members = PostgresExtensionMembers::default();
    for (kind, name, signature) in crate::db::postgres::list_extension_member_objects(&pool, schema).await? {
        if kind == "RELATION" {
            members.relation_names.insert(name);
        } else if kind == "FUNCTION" {
            members.function_keys.insert((name, signature));
        }
    }
    Ok(members)
}

fn is_postgres_extension_member_routine(object: &crate::types::ObjectInfo, members: &PostgresExtensionMembers) -> bool {
    members.function_keys.contains(&(object.name.clone(), object.signature.clone().unwrap_or_default()))
}

async fn list_postgres_export_sequences(
    state: &crate::connection::AppState,
    pool_key: &str,
    schema: &str,
    selected_tables: &[String],
    excluded_tables: &[String],
    include_objects: bool,
    fail_on_error: bool,
) -> Result<Vec<PostgresExportSequence>, String> {
    let pool = {
        let connections = state.connections.read().await;
        match connections.get(pool_key) {
            Some(crate::connection::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, \
              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'), \
              COALESCE(s.seqcycle, false), \
              COALESCE(s.seqcache::text, '1'), \
              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_namespace tn ON tn.oid = t.relnamespace AND tn.nspname = n.nspname \
             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())?;

    let selected: HashSet<&str> = selected_tables.iter().map(String::as_str).collect();
    let excluded: HashSet<&str> = excluded_tables.iter().map(String::as_str).collect();
    let mut sequences = rows
        .iter()
        .map(|row| PostgresExportSequence {
            name: row.get::<_, String>(0),
            data_type: row.get::<_, String>(1),
            start_value: row.get::<_, String>(2),
            min_value: row.get::<_, String>(3),
            max_value: row.get::<_, String>(4),
            increment: row.get::<_, String>(5),
            cycle: row.get::<_, bool>(6),
            cache_value: row.get::<_, String>(7),
            last_value: None,
            owner_table: row.get::<_, Option<String>>(8),
            owner_column: row.get::<_, Option<String>>(9),
        })
        .filter(|sequence| {
            sequence.owner_table.as_deref().is_none_or(|owner_table| !excluded.contains(owner_table))
                && (selected.is_empty()
                    || sequence.owner_table.as_deref().is_some_and(|owner_table| selected.contains(owner_table)))
        })
        .filter(|sequence| sequence.owner_table.is_some() || (include_objects && selected.is_empty()))
        .collect::<Vec<_>>();

    if sequences.is_empty() {
        return Ok(sequences);
    }

    let last_values = client
        .query(
            "SELECT c.relname, pg_sequence_last_value(c.oid)::text \
             FROM pg_class c \
             JOIN pg_namespace n ON n.oid = c.relnamespace \
             WHERE c.relkind = 'S' AND n.nspname = $1",
            &[&schema],
        )
        .await;
    match last_values {
        Ok(rows) => {
            for row in rows {
                let name: String = row.get(0);
                let last_value: Option<String> = row.get(1);
                if let Some(sequence) = sequences.iter_mut().find(|sequence| sequence.name == name) {
                    sequence.last_value = last_value;
                }
            }
        }
        Err(error) if fail_on_error => return Err(error.to_string()),
        Err(_) => {}
    }

    Ok(sequences)
}

pub fn is_export_cancelled_now(export_id: &str) -> bool {
    EXPORT_CANCELLED.read().map(|cancelled| cancelled.contains(export_id)).unwrap_or(false)
}

pub async fn is_export_cancelled(export_id: &str) -> bool {
    is_export_cancelled_now(export_id)
}

pub async fn set_export_cancelled(export_id: &str) {
    if let Ok(mut cancelled) = EXPORT_CANCELLED.write() {
        cancelled.insert(export_id.to_string());
    }
}

pub async fn clear_export_cancelled(export_id: &str) {
    if let Ok(mut cancelled) = EXPORT_CANCELLED.write() {
        cancelled.remove(export_id);
    }
}

/// Await one export operation while still observing the export-id cancellation
/// marker. Metadata helpers ultimately await database-driver futures that do
/// not accept a cancellation token; polling here keeps the export task
/// responsive and dropping the pending future follows the same bounded
/// prefetch cancellation behavior used below.
async fn await_export_operation<T, F>(export_id: &str, operation: F) -> Result<T, String>
where
    F: Future<Output = Result<T, String>>,
{
    tokio::pin!(operation);
    loop {
        if is_export_cancelled_now(export_id) {
            return Err(EXPORT_CANCELLED_ERROR.to_string());
        }
        tokio::select! {
            biased;
            result = &mut operation => {
                return if is_export_cancelled_now(export_id) {
                    Err(EXPORT_CANCELLED_ERROR.to_string())
                } else {
                    result
                };
            },
            _ = tokio::time::sleep(EXPORT_CANCEL_POLL_INTERVAL) => {}
        }
    }
}

pub async fn begin_database_backup_snapshot_core(
    state: &crate::connection::AppState,
    connection_id: &str,
    database: &str,
) -> Result<DatabaseBackupSnapshot, String> {
    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}"))?;
    if !matches!(db_type, DatabaseType::Mysql | DatabaseType::Postgres) {
        return Err("Consistent database backup snapshots are only supported for MySQL and PostgreSQL".to_string());
    }

    let session_id = crate::query::begin_database_backup_snapshot(state, connection_id, database).await?;
    let schemas = if matches!(db_type, DatabaseType::Postgres) {
        const POSTGRES_BACKUP_SCHEMAS_SQL: &str = "SELECT n.nspname FROM pg_catalog.pg_namespace n \
             WHERE n.nspname NOT IN ('information_schema', 'pg_catalog', 'pg_toast') \
             AND n.nspname NOT LIKE 'pg_toast_temp_%' \
             AND n.nspname NOT LIKE 'pg_temp_%' ORDER BY n.nspname";
        let results = crate::query::execute_in_manual_transaction(
            state,
            &session_id,
            POSTGRES_BACKUP_SCHEMAS_SQL,
            database,
            None,
            Some(10_000),
        )
        .await?;
        results
            .into_iter()
            .next()
            .map(|result| {
                result
                    .rows
                    .into_iter()
                    .filter_map(|row| row.into_iter().next())
                    .filter_map(|value| value.as_str().map(str::to_string))
                    .collect()
            })
            .unwrap_or_default()
    } else {
        vec![database.to_string()]
    };
    if schemas.is_empty() {
        let _ = crate::query::rollback_manual_transaction(state, &session_id).await;
        return Err(format!("No schemas are available in database {database}"));
    }
    Ok(DatabaseBackupSnapshot { session_id, schemas })
}

/// 只有确认底层支持并发请求的多连接池才允许并发预取导出元数据。
/// SqlServer（Arc<Mutex> 串行客户端）、Agent/ExternalDriver（插件请求超时覆盖
/// 排队时间且超时会终止 sidecar）、SQLite/DuckDB 等单连接类型都必须回退串行。
fn concurrent_metadata_prefetch_allowed(pool_kind: Option<&crate::connection::PoolKind>) -> bool {
    matches!(
        pool_kind,
        Some(crate::connection::PoolKind::Postgres(_))
            | Some(crate::connection::PoolKind::Mysql(..))
            | Some(crate::connection::PoolKind::ClickHouse(_))
    )
}

fn database_export_metadata_prefetch_concurrency(db_type: DatabaseType) -> usize {
    // PostgreSQL exports can hold a snapshot connection while metadata and UI
    // requests share the base pool. Keep enough capacity available for normal
    // browsing instead of filling nearly the entire ten-connection pool.
    if db_type == DatabaseType::Postgres {
        4
    } else {
        8
    }
}

fn record_export_error<W: Write>(file: &mut W, fail_on_error: bool, message: String) -> Result<(), String> {
    if fail_on_error {
        Err(message)
    } else {
        writeln!(file, "-- ERROR {message}").map_err(|error| format!("Failed to write file: {error}"))
    }
}

fn mysql_spatial_export_marker_expression(column: &str) -> String {
    let quoted = quote_identifier(column, &DatabaseType::Mysql);
    format!(
        "CASE WHEN {quoted} IS NULL THEN NULL ELSE CONCAT('DBX_WKB:', ST_SRID({quoted}), ':', HEX(ST_AsWKB({quoted}))) END AS {quoted}"
    )
}

fn database_export_select_list(columns: &[String], column_types: &[Option<String>], db_type: &DatabaseType) -> String {
    columns
        .iter()
        .enumerate()
        .map(|(index, column)| {
            if *db_type == DatabaseType::Mysql
                && column_types.get(index).and_then(|value| value.as_deref()).is_some_and(is_mysql_spatial_export_type)
            {
                mysql_spatial_export_marker_expression(column)
            } else {
                quote_identifier(column, db_type)
            }
        })
        .collect::<Vec<_>>()
        .join(", ")
}

pub(crate) fn replace_database_export_select_list(
    sql: String,
    columns: &[String],
    column_types: &[Option<String>],
    db_type: &DatabaseType,
) -> String {
    let original = columns.iter().map(|column| quote_identifier(column, db_type)).collect::<Vec<_>>().join(", ");
    let replacement = database_export_select_list(columns, column_types, db_type);
    if replacement == original {
        return sql;
    }
    let prefix = format!("SELECT {original}");
    if !sql.starts_with(&prefix) {
        log::warn!(
            "MySQL spatial database export could not replace its SELECT list; geometry columns will be exported as WKT"
        );
        return sql;
    }
    format!("SELECT {replacement}{}", &sql[prefix.len()..])
}

fn database_export_select_sql(
    columns: &[String],
    column_types: &[Option<String>],
    table: &str,
    schema: &str,
    db_type: &DatabaseType,
) -> String {
    let columns = database_export_select_list(columns, column_types, db_type);
    let table = crate::transfer::qualified_table(table, schema, db_type, None);
    format!("SELECT {columns} FROM {table}")
}

fn write_database_export_rows<W: Write>(
    file: &mut W,
    rows: &[Vec<Value>],
    columns: &[String],
    column_types: &[Option<String>],
    column_extras: &[Option<String>],
    table: &str,
    schema: &str,
    db_type: &DatabaseType,
) -> Result<(), String> {
    let insert_indices = columns
        .iter()
        .enumerate()
        .filter(|(index, column)| {
            is_export_insert_column(
                Some(*db_type),
                column,
                column_types.get(*index).and_then(|value| value.as_deref()),
                column_extras.get(*index).and_then(|value| value.as_deref()),
            )
        })
        .map(|(index, _)| index)
        .collect::<Vec<_>>();
    if insert_indices.is_empty() {
        return Ok(());
    }
    let filtered_columns;
    let filtered_column_types;
    let filtered_column_extras;
    let filtered_rows;
    let (insert_columns, insert_column_types, insert_column_extras, insert_rows) = if insert_indices.len()
        == columns.len()
    {
        (columns, column_types, column_extras, rows)
    } else {
        filtered_columns = insert_indices.iter().map(|index| columns[*index].clone()).collect::<Vec<_>>();
        filtered_column_types =
            insert_indices.iter().map(|index| column_types.get(*index).cloned().unwrap_or(None)).collect::<Vec<_>>();
        filtered_column_extras =
            insert_indices.iter().map(|index| column_extras.get(*index).cloned().unwrap_or(None)).collect::<Vec<_>>();
        filtered_rows = rows
            .iter()
            .map(|row| insert_indices.iter().map(|index| row.get(*index).cloned().unwrap_or(Value::Null)).collect())
            .collect::<Vec<Vec<Value>>>();
        (
            filtered_columns.as_slice(),
            filtered_column_types.as_slice(),
            filtered_column_extras.as_slice(),
            filtered_rows.as_slice(),
        )
    };
    // Database exports use the same table qualification as the SELECT/DDL
    // path and the legacy typed INSERT writer. In particular, MySQL uses the
    // selected database rather than a schema-qualified table name.
    let qualified_table_name = crate::transfer::qualified_table(table, schema, db_type, None);
    // Batch database exports do not currently thread a per-connection identifier
    // quote through BuildDatabaseSqlExportOptions; Kingbase MySQL-compat users
    // should fall back to the single-table export path which carries the quote.
    let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
        database_type: Some(*db_type),
        identifier_quote: None,
        schema: (!schema.is_empty()).then(|| schema.to_string()),
        table_name: Some(table.to_string()),
        qualified_table_name: Some(qualified_table_name),
        columns: insert_columns.to_vec(),
        column_types: insert_column_types.to_vec(),
        column_extras: insert_column_extras.to_vec(),
        rows: insert_rows.to_vec(),
        batch_size: Some(DATABASE_EXPORT_INSERT_BATCH_SIZE),
    })?;
    for statement in statements {
        writeln!(file, "{statement}\n").map_err(|error| format!("Failed to write file: {error}"))?;
    }
    Ok(())
}

fn emit_database_export_running(
    on_progress: &(impl Fn(ExportProgress) + Sync),
    export_id: &str,
    current_object: impl Into<String>,
    object_index: usize,
    total_objects: usize,
    rows_exported: u64,
    preparing: bool,
) {
    on_progress(ExportProgress {
        export_id: export_id.to_string(),
        current_object: current_object.into(),
        object_index,
        total_objects,
        rows_exported,
        total_rows: None,
        status: ExportStatus::Running,
        error: None,
        preparing,
    });
}

fn emit_database_export_cancelled(
    on_progress: &(impl Fn(ExportProgress) + Sync),
    export_id: &str,
    current_object: impl Into<String>,
    object_index: usize,
    total_objects: usize,
    rows_exported: u64,
) {
    on_progress(ExportProgress {
        export_id: export_id.to_string(),
        current_object: current_object.into(),
        object_index,
        total_objects,
        rows_exported,
        total_rows: None,
        status: ExportStatus::Cancelled,
        error: None,
        preparing: false,
    });
}

fn export_destination_state_key(dir: &std::path::Path) -> String {
    format!("database_export_destination:{}", dir.to_string_lossy())
}

/// Records the destination identity for a scheduled backup as soon as it is
/// configured, not just after its first successful export. Scheduled plans
/// live in the frontend and may not run for hours after being saved; without
/// an eager record here, a destination whose mount disappears before its
/// very first run is indistinguishable from a brand-new local folder to
/// `ensure_export_destination_dir` (both have no recorded state) and gets
/// silently recreated on the wrong filesystem. The schedule editor only
/// accepts directories selected from the filesystem, so a missing path here
/// means the destination vanished before its identity could be recorded and
/// the schedule must not be saved. See #6327.
pub async fn record_export_destination_identity(
    state: &crate::connection::AppState,
    dir: &std::path::Path,
) -> Result<(), String> {
    if !dir.is_dir() {
        return Err(format!(
            "Backup directory {} does not exist or is not a directory. Select an existing destination before saving the schedule.",
            dir.display()
        ));
    }
    save_export_destination_dir_device_id(state, dir).await
}

async fn save_export_destination_dir_device_id(
    state: &crate::connection::AppState,
    dir: &std::path::Path,
) -> Result<(), String> {
    let value = match export_destination_device_id_for_path(dir) {
        Some(dev) => dev.to_le_bytes().to_vec(),
        None => Vec::new(),
    };
    state.storage.save_state(&export_destination_state_key(dir), &value, "application/octet-stream").await
}

/// Ensures `dir` exists for an export destination, without ever silently
/// recreating a directory that previously produced a successful export (or
/// was recorded via [`record_export_destination_identity`]) and has since
/// disappeared. Auto-creating on every run is what the original fix for
/// #6109 did, but that is unsafe for a destination on a removable or network
/// drive: if the mount is temporarily gone when a run executes, blindly
/// recreating the path resurrects it on the local root filesystem and the
/// export "succeeds" while silently writing to the wrong disk. A directory
/// dbx has never seen before is safe to create (normal first-time
/// configuration of a local folder); a directory dbx has seen before but
/// that is now missing, or that now resolves to a different filesystem than
/// last time, is refused instead. See #6327.
///
/// Returns the device identity that was just verified (or recorded for a
/// newly created directory), if the current platform can determine one, so
/// the caller can re-verify it against the file it actually opens -- the
/// directory check here and the later `File::create` are separate
/// operations, and the mount can change in between.
async fn ensure_export_destination_dir(
    state: &crate::connection::AppState,
    dir: &std::path::Path,
) -> Result<Option<u64>, String> {
    let key = export_destination_state_key(dir);
    let recorded_dev: Option<Option<u64>> = state
        .storage
        .load_state(&key)
        .await?
        .map(|(bytes, _content_type)| <[u8; 8]>::try_from(bytes.as_slice()).ok().map(u64::from_le_bytes));

    if dir.is_dir() {
        if let Some(Some(recorded_dev)) = recorded_dev {
            if let Some(current_dev) = export_destination_device_id_for_path(dir) {
                if current_dev != recorded_dev {
                    return Err(format!(
                        "Backup directory {} now resolves to a different filesystem than the last \
                         successful export to this location. Refusing to write here automatically -- \
                         if this directory is on a removable or network drive, make sure the correct \
                         drive is connected before running the backup.",
                        dir.display()
                    ));
                }
            }
        }
    } else {
        if recorded_dev.is_some() {
            return Err(format!(
                "Backup directory {} is missing. It was configured or previously used for exports to \
                 this location, so dbx will not recreate it automatically -- if this is on a removable \
                 or network drive, reconnect it and try again.",
                dir.display()
            ));
        }
        std::fs::create_dir_all(dir).map_err(|e| format!("Failed to create backup directory: {e}"))?;
    }

    save_export_destination_dir_device_id(state, dir).await?;
    Ok(export_destination_device_id_for_path(dir))
}

/// Whether a destination's identity, checked once via [`ensure_export_destination_dir`]
/// and then again against the file dbx actually opened, indicates the mount
/// changed in between. An unknown expected identity has nothing to compare,
/// but once an expected identity is known, failing to identify the opened
/// handle must fail closed rather than allowing an unverified write.
fn export_destination_identity_mismatch(expected: Option<u64>, actual: Option<u64>) -> bool {
    expected.is_some_and(|expected| actual != Some(expected))
}

#[cfg(unix)]
fn export_destination_device_id_for_path(dir: &std::path::Path) -> Option<u64> {
    use std::os::unix::fs::MetadataExt;
    std::fs::metadata(dir).ok().map(|metadata| metadata.dev())
}

#[cfg(unix)]
fn export_destination_device_id_for_file(file: &std::fs::File) -> Option<u64> {
    use std::os::unix::fs::MetadataExt;
    file.metadata().ok().map(|metadata| metadata.dev())
}

#[cfg(windows)]
fn export_destination_device_id_for_path(dir: &std::path::Path) -> Option<u64> {
    windows_export_destination::device_id_for_path(dir)
}

#[cfg(windows)]
fn export_destination_device_id_for_file(file: &std::fs::File) -> Option<u64> {
    windows_export_destination::device_id_for_handle(file)
}

#[cfg(not(any(unix, windows)))]
fn export_destination_device_id_for_path(_dir: &std::path::Path) -> Option<u64> {
    None
}

#[cfg(not(any(unix, windows)))]
fn export_destination_device_id_for_file(_file: &std::fs::File) -> Option<u64> {
    None
}

/// Windows has no stable `std` API for a directory or file's volume identity
/// (`MetadataExt::volume_serial_number` is still gated behind the unstable
/// `windows_by_handle` feature), so this queries `dwVolumeSerialNumber` from
/// `BY_HANDLE_FILE_INFORMATION` directly. Using the *handle* rather than
/// re-resolving the path is what makes `export_destination_device_id_for_file`
/// safe to call on an already-open `File`: it reports the volume the handle
/// was actually opened against, not whatever currently sits at that path.
#[cfg(windows)]
mod windows_export_destination {
    use std::os::windows::ffi::OsStrExt;
    use std::os::windows::io::AsRawHandle;
    use std::path::Path;
    use windows_sys::Win32::Foundation::{CloseHandle, HANDLE, INVALID_HANDLE_VALUE};
    use windows_sys::Win32::Storage::FileSystem::{
        CreateFileW, GetFileInformationByHandle, BY_HANDLE_FILE_INFORMATION, FILE_FLAG_BACKUP_SEMANTICS,
        FILE_SHARE_DELETE, FILE_SHARE_READ, FILE_SHARE_WRITE, OPEN_EXISTING,
    };

    pub(super) fn device_id_for_path(path: &Path) -> Option<u64> {
        let mut wide: Vec<u16> = path.as_os_str().encode_wide().collect();
        wide.push(0);
        let handle = unsafe {
            CreateFileW(
                wide.as_ptr(),
                0,
                FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
                std::ptr::null(),
                OPEN_EXISTING,
                FILE_FLAG_BACKUP_SEMANTICS,
                std::ptr::null_mut(),
            )
        };
        if handle == INVALID_HANDLE_VALUE {
            return None;
        }
        let result = volume_serial_number(handle);
        unsafe { CloseHandle(handle) };
        result
    }

    pub(super) fn device_id_for_handle(file: &std::fs::File) -> Option<u64> {
        volume_serial_number(file.as_raw_handle() as HANDLE)
    }

    fn volume_serial_number(handle: HANDLE) -> Option<u64> {
        let mut info: BY_HANDLE_FILE_INFORMATION = unsafe { std::mem::zeroed() };
        let ok = unsafe { GetFileInformationByHandle(handle, &mut info) };
        (ok != 0).then_some(info.dwVolumeSerialNumber as u64)
    }
}

pub async fn export_database_sql_core(
    state: &crate::connection::AppState,
    request: &DatabaseExportRequest,
    on_progress: impl Fn(ExportProgress) + Sync,
) -> Result<(), String> {
    // Keep the large export state machine on the heap. Besides making the
    // caller future small, this prevents the metadata-prefetch locals from
    // exhausting the bounded stack used by test and runtime worker threads.
    let result = Box::pin(export_database_sql_core_inner(state, request, &on_progress)).await;
    if result.as_ref().err().is_some_and(|error| error == EXPORT_CANCELLED_ERROR) {
        // Every caller (Tauri and web SSE) needs a terminal Cancelled event;
        // returning the marker as an error would leave the web EventSource
        // without a terminal event and surface cancellation as Error in Tauri.
        emit_database_export_cancelled(&on_progress, &request.export_id, String::new(), 0, 0, 0);
        Ok(())
    } else {
        result
    }
}

async fn export_database_sql_core_inner(
    state: &crate::connection::AppState,
    request: &DatabaseExportRequest,
    on_progress: impl Fn(ExportProgress) + Sync,
) -> Result<(), String> {
    let _snapshot_keep_alive = if let Some(snapshot_session_id) = request.snapshot_session_id.as_deref() {
        Some(crate::query::keep_manual_transaction_alive(state, snapshot_session_id).await?)
    } else {
        None
    };

    // Emit immediately so the UI is never blank while we list schema metadata.
    emit_database_export_running(&on_progress, &request.export_id, "", 0, 0, 0, true);

    // 1. Get database type
    let db_type = state
        .configs
        .read()
        .await
        .get(&request.connection_id)
        .map(|c| c.db_type)
        .ok_or_else(|| format!("Connection config not found: {}", request.connection_id))?;

    // 2. Get pool
    let client_session_id = database_export_client_session_id(&request.export_id);
    let pool_key = Box::pin(state.get_or_create_pool_for_session(
        &request.connection_id,
        Some(&request.database),
        Some(&client_session_id),
    ))
    .await?;

    // 3. List tables
    let all_tables = Box::pin(crate::schema::list_tables_core(
        state,
        &request.connection_id,
        &request.database,
        &request.schema,
        None,
        None,
        None,
        None,
        None,
    ))
    .await?;
    // 4. Create file
    let mut expected_destination_dev = None;
    if let Some(parent) = std::path::Path::new(&request.file_path).parent() {
        if !parent.as_os_str().is_empty() {
            expected_destination_dev = ensure_export_destination_dir(state, parent).await?;
        }
    }
    let file = std::fs::File::create(&request.file_path).map_err(|e| format!("Failed to write file: {e}"))?;
    // The directory check above and this `File::create` are separate
    // operations: the mount can disappear and be replaced by something else
    // at the same path in between. Re-check the identity of the handle we
    // actually opened, not just the path, and refuse to keep a backup that
    // landed on the wrong filesystem. See #6327.
    if export_destination_identity_mismatch(expected_destination_dev, export_destination_device_id_for_file(&file)) {
        drop(file);
        let _ = std::fs::remove_file(&request.file_path);
        return Err(format!(
            "Backup destination for {} changed while opening the output file -- the directory now \
             resolves to a different filesystem than the one just verified. If a removable or network \
             drive was disconnected and reconnected, retry the backup.",
            request.file_path
        ));
    }
    let mut file = BufWriter::new(file);

    let create_database_preamble = if request.include_create_database && matches!(db_type, DatabaseType::Mysql) {
        Some(mysql_database_export_preamble_for_request(state, request).await)
    } else {
        None
    };

    // 5. Write header
    let timestamp = chrono::Local::now().format("%Y-%m-%d %H:%M:%S");
    writeln!(file, "-- Database export: {}", request.database).map_err(|e| format!("Failed to write file: {e}"))?;
    writeln!(file, "-- Date: {timestamp}").map_err(|e| format!("Failed to write file: {e}"))?;
    writeln!(file, "-- Generated by DBX").map_err(|e| format!("Failed to write file: {e}"))?;
    writeln!(file).map_err(|e| format!("Failed to write file: {e}"))?;

    if let Some(preamble) = create_database_preamble {
        writeln!(file, "-- Database setup").map_err(|e| format!("Failed to write file: {e}"))?;
        writeln!(file, "{preamble}").map_err(|e| format!("Failed to write file: {e}"))?;
    }

    // 6. For MySQL: disable foreign key checks
    if matches!(db_type, DatabaseType::Mysql) {
        writeln!(file, "SET FOREIGN_KEY_CHECKS = 0;\n").map_err(|e| format!("Failed to write file: {e}"))?;
    }

    // 7. Separate tables and views
    let postgres_extension_members =
        if matches!(db_type, DatabaseType::Postgres) && (request.include_structure || request.include_objects) {
            match list_postgres_extension_members(state, &pool_key, &request.schema).await {
                Ok(members) => members,
                Err(e) => {
                    record_export_error(&mut file, request.fail_on_error, format!("reading extension members: {e}"))?;
                    PostgresExtensionMembers::default()
                }
            }
        } else {
            PostgresExtensionMembers::default()
        };
    let postgres_extensions = if request.include_structure && matches!(db_type, DatabaseType::Postgres) {
        match crate::schema::list_extensions_core(
            state,
            &request.connection_id,
            &request.database,
            Some(&request.schema),
        )
        .await
        {
            Ok(extensions) => extensions
                .into_iter()
                .map(|extension| PostgresExportExtension {
                    name: extension.name,
                    schema: extension.schema.unwrap_or_else(|| request.schema.clone()),
                })
                .collect(),
            Err(e) => {
                record_export_error(&mut file, request.fail_on_error, format!("exporting extensions: {e}"))?;
                Vec::new()
            }
        }
    } else {
        Vec::new()
    };
    let all_tables = filter_export_table_infos(all_tables, &request.selected_tables, &request.excluded_tables)
        .into_iter()
        .filter(|table| !postgres_extension_members.relation_names.contains(&table.name))
        .collect::<Vec<_>>();
    let mut tables: Vec<_> = all_tables.iter().filter(|t| !t.table_type.contains("VIEW")).collect();
    let mut views: Vec<_> = all_tables.iter().filter(|t| t.table_type.contains("VIEW")).collect();
    if request.include_objects && db_type == DatabaseType::Mysql && views.len() > 1 {
        match list_mysql_export_view_dependencies(state, &request.connection_id, &request.database).await {
            Ok(dependencies) => views = sort_export_views_by_dependencies(&views, &dependencies),
            Err(error) => {
                log::debug!(
                    "[database-export] failed to resolve MySQL view dependencies for {}: {error}",
                    request.database
                );
            }
        }
    }
    let postgres_sequences = if request.include_structure && matches!(db_type, DatabaseType::Postgres) {
        match await_export_operation(
            &request.export_id,
            list_postgres_export_sequences(
                state,
                &pool_key,
                &request.schema,
                &request.selected_tables,
                &request.excluded_tables,
                request.include_objects,
                request.fail_on_error,
            ),
        )
        .await
        {
            Ok(sequences) => sequences,
            Err(e) if e == EXPORT_CANCELLED_ERROR => return Err(EXPORT_CANCELLED_ERROR.to_string()),
            Err(e) => {
                record_export_error(&mut file, request.fail_on_error, format!("exporting sequences: {e}"))?;
                Vec::new()
            }
        }
    } else {
        Vec::new()
    };

    // Sort tables by foreign key dependency so referenced (parent) tables are
    // exported before referencing (child) tables. MySQL exports always emit
    // `SET FOREIGN_KEY_CHECKS = 0`, so both the generated DDL and any INSERTs
    // already tolerate child-before-parent ordering; reordering away from the
    // alphabetical listing there only makes the output look shuffled to users
    // without providing any correctness benefit.
    if tables.len() > 1 && db_type != DatabaseType::Mysql {
        let table_names: Vec<String> = tables.iter().map(|t| t.name.clone()).collect();
        match crate::transfer::sort_tables_by_fk_dependency(
            state,
            &request.connection_id,
            &request.database,
            &request.schema,
            &table_names,
            true,
        )
        .await
        {
            Ok(sorted_names) => {
                tables.sort_by_key(|t| sorted_names.iter().position(|n| n == &t.name).unwrap_or(usize::MAX));
            }
            Err(error) if request.fail_on_error => {
                return Err(format!("Failed to resolve table dependency order: {error}"));
            }
            Err(_) => {}
        }
    }

    // 8. Discover optional schema-wide objects before calculating workload.
    let mut procedures: Vec<crate::types::ObjectInfo> = Vec::new();
    let mut functions: Vec<crate::types::ObjectInfo> = Vec::new();

    if exports_database_routines(request) {
        match crate::schema::list_objects_core(
            state,
            &request.connection_id,
            &request.database,
            &request.schema,
            None,
            None,
            None,
            None,
            None,
        )
        .await
        {
            Ok(objects) => {
                for obj in &objects {
                    let ot = obj.object_type.to_uppercase();
                    if is_postgres_extension_member_routine(obj, &postgres_extension_members) {
                        continue;
                    }
                    if ot.contains("PROCEDURE") {
                        procedures.push(obj.clone());
                    } else if ot.contains("FUNCTION") {
                        functions.push(obj.clone());
                    }
                }
            }
            Err(error) if request.fail_on_error => return Err(format!("Failed to list database objects: {error}")),
            Err(_) => {}
        }
    }

    // A determinate total must describe the same object categories guarded by
    // the execution branches below, not every object discovered in the schema.
    let total_objects = database_export_total_objects(
        request,
        &DatabaseExportObjectCounts {
            tables: tables.len(),
            views: views.len(),
            sequences: postgres_sequences.len(),
            extensions: postgres_extensions.len(),
            procedures: procedures.len(),
            functions: functions.len(),
        },
    );

    let mut object_index: usize = 0;
    let mut total_rows_exported = 0_u64;
    let mut deferred_postgres_triggers = Vec::new();
    // total_objects is known later for the write phase; preparing updates stay
    // presence-only so the UI does not show a counter that later resets.
    emit_database_export_running(&on_progress, &request.export_id, "", 0, 0, 0, true);

    let batch_size = if request.batch_size == 0 { 1000 } else { request.batch_size };

    // 预取各表的 DDL 与列元数据：逐表串行往返在多表数据库上是整库导出耗时的
    // 主要来源（每表 1-2 次网络往返 × 表数）。有界并发预取后，下方写出循环仍按
    // 原顺序消费，文件内容与逐表查询完全一致。放在写出循环之前，避免准备态与导出态来回跳。
    struct PrefetchedTableMetadata {
        ddl: Option<Result<String, String>>,
        columns: Option<Result<Vec<crate::db::ColumnInfo>, String>>,
    }
    let mut prefetched_table_metadata: Vec<Option<PrefetchedTableMetadata>> = Vec::new();
    prefetched_table_metadata.resize_with(tables.len(), || None);
    // 防护门按「实际连接池种类」放行，而非数据库类型的能力标记：只有确认底层
    // 支持并发请求的多连接池（Postgres/MySQL/ClickHouse）才启用并发预取。反例：
    // 原生 SQL Server 是 Arc<Mutex<..>> 串行客户端；Agent/外部 JDBC（含 SQL Server
    // legacy profile、PrestoSQL 等路由结果）的插件请求超时覆盖排队时间且超时会
    // 终止 sidecar；SQLite/DuckDB 等为单连接。被挡住的场景预取 Vec 保持全 None，
    // 写出循环内的 None 回退路径即原有的逐表串行直查行为。
    let concurrent_prefetch_is_safe =
        match state.get_or_create_pool(&request.connection_id, Some(&request.database)).await {
            Ok(metadata_pool_key) => {
                concurrent_metadata_prefetch_allowed(state.connections.read().await.get(&metadata_pool_key))
            }
            // 建池失败时不预取，让写出循环的直查路径按原有方式报告错误
            Err(_) => false,
        };
    if concurrent_prefetch_is_safe
        && exports_database_tables(request)
        && !tables.is_empty()
        && !is_export_cancelled(&request.export_id).await
    {
        use futures::StreamExt;
        let prefetch_targets: Vec<(usize, String)> =
            tables.iter().enumerate().map(|(index, table_info)| (index, table_info.name.clone())).collect();
        let mut prefetch_stream =
            futures::stream::iter(prefetch_targets.into_iter().map(|(index, table_name)| async move {
                if is_export_cancelled_now(&request.export_id) {
                    return (index, PrefetchedTableMetadata { ddl: None, columns: None });
                }
                let ddl = if request.include_structure {
                    Some(
                        await_export_operation(
                            &request.export_id,
                            crate::schema::get_table_relation_export_ddl_core(
                                state,
                                &request.connection_id,
                                &request.database,
                                &request.schema,
                                &table_name,
                                None,
                            ),
                        )
                        .await,
                    )
                } else {
                    None
                };
                if is_export_cancelled_now(&request.export_id) {
                    return (index, PrefetchedTableMetadata { ddl, columns: None });
                }
                let columns = if request.include_data {
                    Some(
                        await_export_operation(
                            &request.export_id,
                            crate::schema::get_columns_core(
                                state,
                                &request.connection_id,
                                &request.database,
                                &request.schema,
                                &table_name,
                            ),
                        )
                        .await,
                    )
                } else {
                    None
                };
                (index, PrefetchedTableMetadata { ddl, columns })
            }))
            .buffer_unordered(database_export_metadata_prefetch_concurrency(db_type));
        while let Some((index, metadata)) = prefetch_stream.next().await {
            if metadata
                .ddl
                .as_ref()
                .is_some_and(|result| result.as_ref().err().is_some_and(|error| error == EXPORT_CANCELLED_ERROR))
                || metadata
                    .columns
                    .as_ref()
                    .is_some_and(|result| result.as_ref().err().is_some_and(|error| error == EXPORT_CANCELLED_ERROR))
            {
                return Err(EXPORT_CANCELLED_ERROR.to_string());
            }
            prefetched_table_metadata[index] = Some(metadata);
            if let Some(table_info) = tables.get(index) {
                // Presence-only updates: no prepare counter that later resets to 0/N.
                emit_database_export_running(
                    &on_progress,
                    &request.export_id,
                    table_info.name.clone(),
                    0,
                    0,
                    total_rows_exported,
                    true,
                );
            }
            // 取消后不再调度新的预取任务（已在途的任务随 stream 释放而中止），
            // 写出循环入口的取消检查负责最终收尾
            if is_export_cancelled_now(&request.export_id) {
                break;
            }
        }
    }

    for extension in &postgres_extensions {
        if is_export_cancelled(&request.export_id).await {
            return Err("Export cancelled".to_string());
        }
        emit_database_export_running(
            &on_progress,
            &request.export_id,
            extension.name.clone(),
            object_index,
            total_objects,
            total_rows_exported,
            false,
        );
        writeln!(file, "{}\n", generate_postgres_extension_ddl(extension))
            .map_err(|e| format!("Failed to write file: {e}"))?;
        object_index += 1;
    }

    for sequence in postgres_sequences.iter().filter(|sequence| sequence.owner_table.is_none()) {
        if is_export_cancelled(&request.export_id).await {
            return Err("Export cancelled".to_string());
        }

        emit_database_export_running(
            &on_progress,
            &request.export_id,
            sequence.name.clone(),
            object_index,
            total_objects,
            total_rows_exported,
            false,
        );

        writeln!(file, "{};\n", generate_postgres_sequence_create_ddl(sequence, &request.schema))
            .map_err(|e| format!("Failed to write file: {e}"))?;
        object_index += 1;
    }

    for (table_index, table_info) in tables.iter().enumerate().filter(|_| exports_database_tables(request)) {
        // Check cancellation
        if is_export_cancelled(&request.export_id).await {
            emit_database_export_cancelled(
                &on_progress,
                &request.export_id,
                table_info.name.clone(),
                object_index,
                total_objects,
                total_rows_exported,
            );
            return Ok(());
        }

        let table_name = &table_info.name;

        // Emit Running progress
        on_progress(ExportProgress {
            export_id: request.export_id.clone(),
            current_object: table_name.clone(),
            object_index,
            total_objects,
            rows_exported: total_rows_exported,
            total_rows: None,
            status: ExportStatus::Running,
            error: None,
            preparing: false,
        });

        // Export structure
        if request.include_structure {
            if request.drop_table_if_exists {
                writeln!(file, "{}\n", drop_table_if_exists_sql(table_name, &request.schema, &db_type))
                    .map_err(|e| format!("Failed to write file: {e}"))?;
            }
            for sequence in postgres_sequences
                .iter()
                .filter(|sequence| sequence.owner_table.as_deref() == Some(table_name.as_str()))
            {
                on_progress(ExportProgress {
                    export_id: request.export_id.clone(),
                    current_object: sequence.name.clone(),
                    object_index,
                    total_objects,
                    rows_exported: total_rows_exported,
                    total_rows: None,
                    status: ExportStatus::Running,
                    error: None,
                    preparing: false,
                });

                writeln!(file, "{};\n", generate_postgres_sequence_create_ddl(sequence, &request.schema))
                    .map_err(|e| format!("Failed to write file: {e}"))?;
                object_index += 1;
            }
            let ddl_result = match prefetched_table_metadata
                .get_mut(table_index)
                .and_then(|m| m.as_mut())
                .and_then(|m| m.ddl.take())
            {
                Some(result) => result,
                None => {
                    await_export_operation(
                        &request.export_id,
                        crate::schema::get_table_relation_export_ddl_core(
                            state,
                            &request.connection_id,
                            &request.database,
                            &request.schema,
                            table_name,
                            None,
                        ),
                    )
                    .await
                }
            };
            if ddl_result.as_ref().err().is_some_and(|error| error == EXPORT_CANCELLED_ERROR) {
                return Err(EXPORT_CANCELLED_ERROR.to_string());
            }
            match ddl_result {
                Ok(ddl) => {
                    let (ddl, triggers) = split_postgres_export_table_triggers(&ddl, db_type);
                    deferred_postgres_triggers.extend(triggers);
                    let ddl = format_export_table_ddl(
                        &ddl,
                        Some(db_type),
                        DdlNormalizeOptions { omit_auto_increment: request.omit_auto_increment },
                    );
                    writeln!(file, "{ddl}\n").map_err(|e| format!("Failed to write file: {e}"))?;
                }
                Err(e) => {
                    record_export_error(
                        &mut file,
                        request.fail_on_error,
                        format!("exporting table structure {table_name}: {e}"),
                    )?;
                }
            }
        }

        // Export data
        if request.include_data {
            // Get columns
            let columns_result = match prefetched_table_metadata
                .get_mut(table_index)
                .and_then(|m| m.as_mut())
                .and_then(|m| m.columns.take())
            {
                Some(result) => result,
                None => {
                    await_export_operation(
                        &request.export_id,
                        crate::schema::get_columns_core(
                            state,
                            &request.connection_id,
                            &request.database,
                            &request.schema,
                            table_name,
                        ),
                    )
                    .await
                }
            };
            if columns_result.as_ref().err().is_some_and(|error| error == EXPORT_CANCELLED_ERROR) {
                return Err(EXPORT_CANCELLED_ERROR.to_string());
            }
            let columns = match columns_result {
                Ok(cols) => cols,
                Err(e) => {
                    record_export_error(
                        &mut file,
                        request.fail_on_error,
                        format!("exporting columns for table {table_name}: {e}"),
                    )?;
                    object_index += 1;
                    continue;
                }
            };
            let col_names = columns.iter().map(|c| c.name.clone()).collect::<Vec<_>>();
            let col_types = columns.iter().map(|c| Some(c.data_type.clone())).collect::<Vec<_>>();
            let col_extras = columns.iter().map(|c| c.extra.clone()).collect::<Vec<_>>();

            if !col_names.is_empty() {
                if let Some(snapshot_session_id) = request.snapshot_session_id.as_deref() {
                    let sql = database_export_select_sql(&col_names, &col_types, table_name, &request.schema, &db_type);
                    crate::query::stream_rows_in_manual_transaction(
                        state,
                        snapshot_session_id,
                        &sql,
                        batch_size,
                        |rows| {
                            if is_export_cancelled_now(&request.export_id) {
                                return Err("Export cancelled".to_string());
                            }
                            write_database_export_rows(
                                &mut file,
                                &rows,
                                &col_names,
                                &col_types,
                                &col_extras,
                                table_name,
                                &request.schema,
                                &db_type,
                            )?;
                            total_rows_exported += rows.len() as u64;
                            on_progress(ExportProgress {
                                export_id: request.export_id.clone(),
                                current_object: table_name.clone(),
                                object_index,
                                total_objects,
                                rows_exported: total_rows_exported,
                                total_rows: None,
                                status: ExportStatus::Running,
                                error: None,
                                preparing: false,
                            });
                            Ok(())
                        },
                    )
                    .await?;
                } else {
                    // Exact COUNT(*) is deliberately skipped for manual database exports. It adds a full
                    // table scan before the real read and does not improve correctness. Progress reports
                    // exported rows while total_rows remains indeterminate.
                    let total_rows = None;
                    let primary_keys = columns
                        .iter()
                        .filter(|column| column.is_primary_key)
                        .map(|column| column.name.clone())
                        .collect::<Vec<_>>();
                    let primary_key_indices = primary_keys
                        .iter()
                        .filter_map(|primary_key| col_names.iter().position(|column| column == primary_key))
                        .collect::<Vec<_>>();
                    let use_keyset = !primary_keys.is_empty() && primary_key_indices.len() == primary_keys.len();
                    let mut last_primary_key_values = Vec::new();
                    let mut offset = 0_u64;

                    loop {
                        if is_export_cancelled(&request.export_id).await {
                            emit_database_export_cancelled(
                                &on_progress,
                                &request.export_id,
                                table_name.clone(),
                                object_index,
                                total_objects,
                                total_rows_exported,
                            );
                            return Ok(());
                        }

                        let sql = if use_keyset {
                            let sql = keyset_pagination_sql_with_identifier_quote(
                                &col_names,
                                table_name,
                                &request.schema,
                                &db_type,
                                &primary_keys,
                                &last_primary_key_values,
                                batch_size,
                                None,
                            );
                            replace_database_export_select_list(sql, &col_names, &col_types, &db_type)
                        } else {
                            let sql = crate::transfer::pagination_sql(
                                &col_names,
                                table_name,
                                &request.schema,
                                &db_type,
                                offset,
                                batch_size,
                            );
                            replace_database_export_select_list(sql, &col_names, &col_types, &db_type)
                        };
                        let result = match crate::transfer::execute_read_on_pool(state, &pool_key, &sql).await {
                            Ok(result) => result,
                            Err(error) => {
                                record_export_error(
                                    &mut file,
                                    request.fail_on_error,
                                    format!("exporting data for table {table_name}: {error}"),
                                )?;
                                break;
                            }
                        };
                        let row_count = result.rows.len();
                        if row_count == 0 {
                            break;
                        }
                        write_database_export_rows(
                            &mut file,
                            &result.rows,
                            &col_names,
                            &col_types,
                            &col_extras,
                            table_name,
                            &request.schema,
                            &db_type,
                        )?;
                        total_rows_exported += row_count as u64;
                        if use_keyset {
                            if let Some(last_row) = result.rows.last() {
                                last_primary_key_values =
                                    primary_key_indices.iter().map(|&index| last_row[index].clone()).collect();
                            }
                        } else {
                            offset += row_count as u64;
                        }
                        on_progress(ExportProgress {
                            export_id: request.export_id.clone(),
                            current_object: table_name.clone(),
                            object_index,
                            total_objects,
                            rows_exported: total_rows_exported,
                            total_rows,
                            status: ExportStatus::Running,
                            error: None,
                            preparing: false,
                        });
                        if row_count < batch_size {
                            break;
                        }
                    }
                }
            }
        }

        object_index += 1;
    }

    if request.include_structure && !postgres_sequences.is_empty() {
        for sequence in &postgres_sequences {
            if let Some(sql) = generate_postgres_sequence_owner_ddl(sequence, &request.schema) {
                writeln!(file, "{};\n", sql).map_err(|e| format!("Failed to write file: {e}"))?;
            }
        }
        for sequence in &postgres_sequences {
            if let Some(sql) = generate_postgres_sequence_setval_sql(sequence, &request.schema) {
                writeln!(file, "{};\n", sql).map_err(|e| format!("Failed to write file: {e}"))?;
            }
        }
    }

    // Export views (if include_objects)
    if request.include_objects {
        for view_info in &views {
            if is_export_cancelled(&request.export_id).await {
                return Err("Export cancelled".to_string());
            }

            let view_name = &view_info.name;

            on_progress(ExportProgress {
                export_id: request.export_id.clone(),
                current_object: view_name.clone(),
                object_index,
                total_objects,
                rows_exported: total_rows_exported,
                total_rows: None,
                status: ExportStatus::Running,
                error: None,
                preparing: false,
            });

            match crate::schema::get_object_source_core(
                state,
                &request.connection_id,
                &request.database,
                &request.schema,
                view_name,
                crate::db::ObjectSourceKind::View,
                None,
                None,
            )
            .await
            {
                Ok(obj_source) => {
                    let source = build_database_export_object_source_sql(
                        db_type,
                        &ObjectSourceKind::View,
                        view_name,
                        &obj_source.source,
                        request.drop_table_if_exists,
                    );
                    if !source.is_empty() {
                        writeln!(file, "{source}\n").map_err(|e| format!("Failed to write file: {e}"))?;
                    }
                }
                Err(e) => {
                    record_export_error(&mut file, request.fail_on_error, format!("exporting view {view_name}: {e}"))?;
                }
            }

            object_index += 1;
        }

        // Export procedures
        for procedure in &procedures {
            if is_export_cancelled(&request.export_id).await {
                return Err("Export cancelled".to_string());
            }

            let proc_name = &procedure.name;

            on_progress(ExportProgress {
                export_id: request.export_id.clone(),
                current_object: proc_name.clone(),
                object_index,
                total_objects,
                rows_exported: total_rows_exported,
                total_rows: None,
                status: ExportStatus::Running,
                error: None,
                preparing: false,
            });

            match crate::schema::get_object_source_core(
                state,
                &request.connection_id,
                &request.database,
                &request.schema,
                proc_name,
                crate::db::ObjectSourceKind::Procedure,
                procedure.signature.as_deref(),
                None,
            )
            .await
            {
                Ok(obj_source) => {
                    let source = build_database_export_object_source_sql(
                        db_type,
                        &ObjectSourceKind::Procedure,
                        proc_name,
                        &obj_source.source,
                        request.drop_table_if_exists,
                    );
                    if !source.is_empty() {
                        writeln!(file, "{source}\n").map_err(|e| format!("Failed to write file: {e}"))?;
                    }
                }
                Err(e) => {
                    record_export_error(
                        &mut file,
                        request.fail_on_error,
                        format!("exporting procedure {proc_name}: {e}"),
                    )?;
                }
            }

            object_index += 1;
        }

        // Export functions
        for function in &functions {
            if is_export_cancelled(&request.export_id).await {
                return Err("Export cancelled".to_string());
            }

            let func_name = &function.name;

            on_progress(ExportProgress {
                export_id: request.export_id.clone(),
                current_object: func_name.clone(),
                object_index,
                total_objects,
                rows_exported: total_rows_exported,
                total_rows: None,
                status: ExportStatus::Running,
                error: None,
                preparing: false,
            });

            match crate::schema::get_object_source_core(
                state,
                &request.connection_id,
                &request.database,
                &request.schema,
                func_name,
                crate::db::ObjectSourceKind::Function,
                function.signature.as_deref(),
                None,
            )
            .await
            {
                Ok(obj_source) => {
                    let source = build_database_export_object_source_sql(
                        db_type,
                        &ObjectSourceKind::Function,
                        func_name,
                        &obj_source.source,
                        request.drop_table_if_exists,
                    );
                    if !source.is_empty() {
                        writeln!(file, "{source}\n").map_err(|e| format!("Failed to write file: {e}"))?;
                    }
                }
                Err(e) => {
                    record_export_error(
                        &mut file,
                        request.fail_on_error,
                        format!("exporting function {func_name}: {e}"),
                    )?;
                }
            }

            object_index += 1;
        }
    }

    // PostgreSQL trigger definitions reference their trigger functions. The
    // table DDL builder returns both statements together, while schema-wide
    // routines are exported below the tables. Keep triggers part of table
    // structure, but write them only after routines so the resulting script
    // is executable in file order.
    for trigger in deferred_postgres_triggers {
        writeln!(file, "{trigger}\n").map_err(|e| format!("Failed to write file: {e}"))?;
    }

    // For MySQL: re-enable foreign key checks
    if matches!(db_type, DatabaseType::Mysql) {
        writeln!(file, "SET FOREIGN_KEY_CHECKS = 1;").map_err(|e| format!("Failed to write file: {e}"))?;
    }

    file.flush().map_err(|e| format!("Failed to finalize export file: {e}"))?;

    // Emit Done progress
    on_progress(ExportProgress {
        export_id: request.export_id.clone(),
        current_object: String::new(),
        object_index,
        total_objects,
        rows_exported: total_rows_exported,
        total_rows: None,
        status: ExportStatus::Done,
        error: None,
        preparing: false,
    });

    Ok(())
}

fn filter_export_table_infos(
    tables: Vec<crate::types::TableInfo>,
    selected_tables: &[String],
    excluded_tables: &[String],
) -> Vec<crate::types::TableInfo> {
    let selected: HashSet<&str> = selected_tables.iter().map(String::as_str).collect();
    let excluded: HashSet<&str> = excluded_tables.iter().map(String::as_str).collect();
    tables
        .into_iter()
        .filter(|table| selected.is_empty() || selected.contains(table.name.as_str()))
        .filter(|table| !excluded.contains(table.name.as_str()))
        .collect()
}

fn drop_table_if_exists_sql(table_name: &str, schema: &str, db_type: &DatabaseType) -> String {
    format!("DROP TABLE IF EXISTS {};", crate::transfer::qualified_table(table_name, schema, db_type, None))
}

fn build_database_export_object_source_sql(
    database_type: DatabaseType,
    object_type: &ObjectSourceKind,
    object_name: &str,
    source: &str,
    drop_if_exists: bool,
) -> String {
    let source = build_export_object_source_sql(database_type, object_type.clone(), source);
    if source.is_empty() || !drop_if_exists || database_type != DatabaseType::Mysql {
        return source;
    }

    let object_type = match object_type {
        ObjectSourceKind::View => "VIEW",
        ObjectSourceKind::Procedure => "PROCEDURE",
        ObjectSourceKind::Function => "FUNCTION",
        _ => return source,
    };
    let object_name = quote_identifier(object_name, &DatabaseType::Mysql);
    format!("DROP {object_type} IF EXISTS {object_name};\n{source}")
}

#[cfg(test)]
mod tests {
    use super::{
        await_export_operation, clear_export_cancelled, concurrent_metadata_prefetch_allowed,
        database_export_metadata_prefetch_concurrency, emit_database_export_cancelled, set_export_cancelled,
        ExportStatus, EXPORT_CANCELLED_ERROR,
    };
    use super::{
        build_database_export_object_source_sql, build_database_sql_export, build_export_insert_statements,
        database_export_select_sql, database_export_total_objects, drop_table_if_exists_sql,
        ensure_export_destination_dir, export_destination_identity_mismatch, filter_export_table_infos,
        format_export_sql_literal, format_export_table_ddl, format_mysql_spatial_export_literal,
        generate_postgres_extension_ddl, generate_postgres_sequence_create_ddl, generate_postgres_sequence_owner_ddl,
        generate_postgres_sequence_setval_sql, is_postgres_extension_member_routine, mysql_database_export_preamble,
        mysql_view_dependencies_from_rows, mysql_view_dependencies_sql, normalize_export_table_ddl,
        record_export_destination_identity, record_export_error, replace_database_export_select_list,
        sort_export_views_by_dependencies, split_postgres_export_table_triggers, write_database_export_rows,
        BuildDatabaseSqlExportOptions, BuildExportInsertStatementsOptions, DatabaseExportObjectCounts,
        DatabaseExportRequest, DdlNormalizeOptions, ExportedTableSql, PostgresExportExtension, PostgresExportSequence,
        PostgresExtensionMembers, DATABASE_EXPORT_INSERT_BATCH_SIZE, DATABASE_EXPORT_ROW_LIMIT,
    };
    use crate::connection::AppState;
    use crate::models::connection::DatabaseType;
    use crate::storage::Storage;
    use crate::types::{ObjectInfo, ObjectSourceKind, TableInfo};
    use serde_json::{json, Value};
    use std::sync::{Arc, Mutex};

    #[tokio::test]
    async fn await_export_operation_drops_pending_metadata_after_cancel() {
        let export_id = format!("cancel-pending-{}", uuid::Uuid::new_v4());
        clear_export_cancelled(&export_id).await;
        let task_export_id = export_id.clone();
        let task = tokio::spawn(async move {
            await_export_operation(&task_export_id, async {
                tokio::time::sleep(std::time::Duration::from_secs(30)).await;
                Ok::<_, String>(())
            })
            .await
        });

        tokio::time::sleep(std::time::Duration::from_millis(10)).await;
        set_export_cancelled(&export_id).await;
        let result = tokio::time::timeout(std::time::Duration::from_secs(1), task)
            .await
            .expect("cancellation should stop a pending metadata future")
            .expect("cancellation task should not panic");
        assert_eq!(result, Err(EXPORT_CANCELLED_ERROR.to_string()));
        clear_export_cancelled(&export_id).await;
    }

    #[tokio::test]
    async fn await_export_operation_preserves_completed_metadata() {
        let export_id = format!("complete-metadata-{}", uuid::Uuid::new_v4());
        clear_export_cancelled(&export_id).await;
        let result = await_export_operation(&export_id, async { Ok::<_, String>(42_u32) }).await;
        assert_eq!(result, Ok(42));
    }

    #[test]
    fn cancelled_progress_is_terminal_and_has_no_error() {
        let events = Arc::new(Mutex::new(Vec::new()));
        let sink = Arc::clone(&events);
        emit_database_export_cancelled(&|progress| sink.lock().unwrap().push(progress), "export-1", "seq", 3, 9, 17);

        let progress = events.lock().unwrap().pop().expect("cancelled progress");
        assert_eq!(progress.export_id, "export-1");
        assert_eq!(progress.current_object, "seq");
        assert_eq!(progress.object_index, 3);
        assert_eq!(progress.total_objects, 9);
        assert_eq!(progress.rows_exported, 17);
        assert!(matches!(progress.status, ExportStatus::Cancelled));
        assert!(progress.error.is_none());
        assert!(!progress.preparing);
    }

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

    fn routine(name: &str, signature: &str) -> ObjectInfo {
        ObjectInfo {
            name: name.to_string(),
            object_type: "FUNCTION".to_string(),
            schema: Some("public".to_string()),
            valid: None,
            signature: Some(signature.to_string()),
            custom_type_kind: None,
            has_members: None,
            comment: None,
            created_at: None,
            updated_at: None,
            parent_schema: None,
            parent_name: None,
            trigger: None,
            xugu_type_members_expandable: None,
        }
    }

    fn export_request(
        include_structure: bool,
        include_data: bool,
        include_objects: bool,
        selected_tables: Vec<String>,
    ) -> DatabaseExportRequest {
        DatabaseExportRequest {
            export_id: "export-1".to_string(),
            connection_id: "connection-1".to_string(),
            database: "database-1".to_string(),
            schema: "public".to_string(),
            file_path: "export.sql".to_string(),
            selected_tables,
            excluded_tables: Vec::new(),
            include_structure,
            include_data,
            include_objects,
            include_create_database: false,
            drop_table_if_exists: false,
            omit_auto_increment: false,
            fail_on_error: false,
            snapshot_session_id: None,
            batch_size: 1000,
        }
    }

    #[test]
    fn export_progress_total_counts_only_requested_object_categories() {
        let counts = DatabaseExportObjectCounts {
            tables: 2,
            views: 1,
            sequences: 2,
            extensions: 1,
            procedures: 1,
            functions: 1,
        };

        let cases = [
            ("structure", export_request(true, false, false, Vec::new()), 5),
            ("data", export_request(false, true, false, Vec::new()), 2),
            ("objects", export_request(false, false, true, Vec::new()), 3),
            ("all", export_request(true, true, true, Vec::new()), 8),
            ("nothing", export_request(false, false, false, Vec::new()), 0),
        ];

        for (name, request, expected) in cases {
            assert_eq!(database_export_total_objects(&request, &counts), expected, "{name}");
        }
    }

    #[test]
    fn mysql_database_export_preamble_preserves_database_settings() {
        assert_eq!(
            mysql_database_export_preamble("app`db", Some("utf8mb4"), Some("utf8mb4_unicode_ci")),
            "CREATE DATABASE IF NOT EXISTS `app``db` CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;\nUSE `app``db`;\n"
        );
        assert_eq!(
            mysql_database_export_preamble("app", None, None),
            "CREATE DATABASE IF NOT EXISTS `app`;\nUSE `app`;\n"
        );
    }

    #[test]
    fn export_progress_total_excludes_schema_routines_for_selected_tables() {
        // Counts are already filtered to the selected table/view set before
        // workload calculation; schema-wide routines remain intentionally out.
        let counts = DatabaseExportObjectCounts {
            tables: 1,
            views: 1,
            sequences: 1,
            extensions: 1,
            procedures: 4,
            functions: 5,
        };
        let request = export_request(true, true, true, vec!["users".to_string(), "active_users".to_string()]);

        assert_eq!(database_export_total_objects(&request, &counts), 4);
    }

    #[test]
    fn postgres_extension_ddl_uses_target_default_version_and_source_schema() {
        let extension = PostgresExportExtension { name: "pg_trgm".to_string(), schema: "addons".to_string() };

        let ddl = generate_postgres_extension_ddl(&extension);

        assert_eq!(ddl, "CREATE EXTENSION IF NOT EXISTS \"pg_trgm\" WITH SCHEMA \"addons\";");
        assert!(!ddl.contains("VERSION"));
    }

    #[test]
    fn postgres_extension_member_filter_keeps_user_overload_with_same_name() {
        let mut members = PostgresExtensionMembers::default();
        members.function_keys.insert(("similarity".to_string(), "text, text".to_string()));

        assert!(is_postgres_extension_member_routine(&routine("similarity", "text, text"), &members));
        assert!(!is_postgres_extension_member_routine(&routine("similarity", "integer, integer"), &members));
        assert!(!is_postgres_extension_member_routine(&routine("user_similarity", "text, text"), &members));
    }

    #[test]
    fn postgres_database_export_defers_table_triggers_without_splitting_function_bodies() {
        let ddl = "CREATE TABLE \"public\".\"work_log\" (\n  \"id\" bigint,\n  \"note\" text DEFAULT ';'::text\n);\n\nCREATE INDEX \"idx_work_log\" ON \"public\".\"work_log\" (\"id\");\n\nCREATE TRIGGER trg_work_log BEFORE INSERT OR UPDATE ON public.work_log FOR EACH ROW EXECUTE FUNCTION fn_work_log_update();";

        let (table_ddl, triggers) = split_postgres_export_table_triggers(ddl, DatabaseType::Postgres);

        assert!(table_ddl.contains("CREATE TABLE"));
        assert!(table_ddl.contains("DEFAULT ';'::text"));
        assert!(table_ddl.contains("CREATE INDEX"));
        assert!(!table_ddl.contains("CREATE TRIGGER"));
        assert_eq!(triggers.len(), 1);
        assert!(triggers[0].starts_with("CREATE TRIGGER trg_work_log"));
    }

    #[test]
    fn postgres_database_export_defers_constraint_triggers_only_for_postgres() {
        let ddl = "CREATE TABLE \"public\".\"items\" (\"id\" bigint);\nCREATE CONSTRAINT TRIGGER items_check AFTER INSERT ON public.items DEFERRABLE INITIALLY DEFERRED FOR EACH ROW EXECUTE FUNCTION check_items();";

        let (postgres_table, postgres_triggers) = split_postgres_export_table_triggers(ddl, DatabaseType::Postgres);
        assert!(!postgres_table.contains("CREATE CONSTRAINT TRIGGER"));
        assert_eq!(postgres_triggers.len(), 1);

        let (mysql_ddl, mysql_triggers) = split_postgres_export_table_triggers(ddl, DatabaseType::Mysql);
        assert_eq!(mysql_ddl, ddl);
        assert!(mysql_triggers.is_empty());
    }

    #[test]
    fn concurrent_prefetch_only_allowed_for_multi_connection_pools() {
        use crate::connection::PoolKind;

        // ChClient::new 只构造 HTTP 客户端，不发起连接
        let clickhouse = PoolKind::ClickHouse(crate::db::clickhouse_driver::ChClient::new(
            "http://127.0.0.1:1",
            None,
            None,
            std::time::Duration::from_secs(1),
        ));
        assert!(concurrent_metadata_prefetch_allowed(Some(&clickhouse)));

        // Agent（JDBC sidecar）请求超时覆盖排队时间，必须回退串行
        let agent = PoolKind::agent(crate::db::agent_driver::AgentDriverClient::test_stub());
        assert!(!concurrent_metadata_prefetch_allowed(Some(&agent)));

        assert!(!concurrent_metadata_prefetch_allowed(None));
    }

    #[test]
    fn postgres_metadata_prefetch_reserves_pool_capacity() {
        assert_eq!(database_export_metadata_prefetch_concurrency(DatabaseType::Postgres), 4);
        assert_eq!(database_export_metadata_prefetch_concurrency(DatabaseType::Mysql), 8);
    }

    #[test]
    fn filters_export_tables_by_selected_names() {
        let tables = vec![table("users", "TABLE"), table("orders", "TABLE"), table("active_users", "VIEW")];

        let filtered = filter_export_table_infos(tables, &["active_users".to_string(), "users".to_string()], &[]);

        assert_eq!(filtered.iter().map(|table| table.name.as_str()).collect::<Vec<_>>(), vec!["users", "active_users"]);
    }

    #[test]
    fn keeps_all_export_tables_when_selection_is_empty() {
        let tables = vec![table("users", "TABLE"), table("orders", "TABLE")];

        let filtered = filter_export_table_infos(tables.clone(), &[], &[]);

        assert_eq!(filtered.iter().map(|table| table.name.as_str()).collect::<Vec<_>>(), vec!["users", "orders"]);
    }

    #[test]
    fn excludes_export_tables_by_name() {
        let tables = vec![table("users", "TABLE"), table("audit_log", "TABLE"), table("active_users", "VIEW")];

        let filtered = filter_export_table_infos(tables, &[], &["audit_log".to_string(), "active_users".to_string()]);

        assert_eq!(filtered.iter().map(|table| table.name.as_str()).collect::<Vec<_>>(), vec!["users"]);
    }

    #[test]
    fn mysql_export_orders_referenced_views_before_dependents() {
        let tables = [table("a_view", "VIEW"), table("z_view", "VIEW")];
        let views = tables.iter().collect::<Vec<_>>();
        let dependencies =
            vec![("a_view".to_string(), "z_view".to_string()), ("z_view".to_string(), "base_table".to_string())];

        let sorted = sort_export_views_by_dependencies(&views, &dependencies);

        assert_eq!(sorted.iter().map(|view| view.name.as_str()).collect::<Vec<_>>(), vec!["z_view", "a_view"]);
    }

    #[test]
    fn mysql_view_dependency_metadata_is_escaped_and_parsed() {
        let sql = mysql_view_dependencies_sql("prod'o");
        assert!(sql.contains("VIEW_SCHEMA = 'prod''o'"));
        assert!(sql.contains("TABLE_SCHEMA = 'prod''o'"));

        let rows = vec![
            vec![json!(" a_view "), json!(" z_view ")],
            vec![Value::Null, json!("ignored")],
            vec![json!(""), json!("ignored")],
        ];
        assert_eq!(mysql_view_dependencies_from_rows(&rows), vec![("a_view".to_string(), "z_view".to_string())]);
    }

    #[test]
    fn exclusions_take_precedence_over_selected_tables() {
        let tables = vec![table("users", "TABLE"), table("orders", "TABLE")];

        let filtered =
            filter_export_table_infos(tables, &["users".to_string(), "orders".to_string()], &["orders".to_string()]);

        assert_eq!(filtered.iter().map(|table| table.name.as_str()).collect::<Vec<_>>(), vec!["users"]);
    }

    #[test]
    fn builds_drop_table_if_exists_with_qualified_mysql_name() {
        let sql = drop_table_if_exists_sql("users", "app", &DatabaseType::Mysql);

        assert_eq!(sql, "DROP TABLE IF EXISTS `users`;");
    }

    #[test]
    fn builds_drop_table_if_exists_without_empty_schema() {
        let sql = drop_table_if_exists_sql("users", "", &DatabaseType::Postgres);

        assert_eq!(sql, "DROP TABLE IF EXISTS \"users\";");
    }

    #[test]
    fn mysql_export_adds_drop_if_exists_for_views_and_escapes_names() {
        let sql = build_database_export_object_source_sql(
            DatabaseType::Mysql,
            &ObjectSourceKind::View,
            "active`rows",
            "CREATE VIEW `active``rows` AS SELECT 1",
            true,
        );

        assert_eq!(sql, "DROP VIEW IF EXISTS `active``rows`;\nCREATE VIEW `active``rows` AS SELECT 1;");
    }

    #[test]
    fn mysql_export_adds_drop_if_exists_before_delimited_routines() {
        let procedure = build_database_export_object_source_sql(
            DatabaseType::Mysql,
            &ObjectSourceKind::Procedure,
            "refresh_cache",
            "CREATE PROCEDURE `refresh_cache`() BEGIN SELECT 1; END",
            true,
        );
        let function = build_database_export_object_source_sql(
            DatabaseType::Mysql,
            &ObjectSourceKind::Function,
            "active_count",
            "CREATE FUNCTION `active_count`() RETURNS INT RETURN 1",
            true,
        );

        assert_eq!(
            procedure,
            "DROP PROCEDURE IF EXISTS `refresh_cache`;\nDELIMITER //\nCREATE PROCEDURE `refresh_cache`() BEGIN SELECT 1; END//\nDELIMITER ;"
        );
        assert_eq!(
            function,
            "DROP FUNCTION IF EXISTS `active_count`;\nDELIMITER //\nCREATE FUNCTION `active_count`() RETURNS INT RETURN 1//\nDELIMITER ;"
        );
    }

    #[test]
    fn object_drop_option_does_not_change_disabled_or_non_mysql_exports() {
        let mysql_without_drop = build_database_export_object_source_sql(
            DatabaseType::Mysql,
            &ObjectSourceKind::View,
            "active_rows",
            "CREATE VIEW `active_rows` AS SELECT 1",
            false,
        );
        let postgres_with_drop = build_database_export_object_source_sql(
            DatabaseType::Postgres,
            &ObjectSourceKind::View,
            "active_rows",
            "CREATE VIEW active_rows AS SELECT 1",
            true,
        );

        assert_eq!(mysql_without_drop, "CREATE VIEW `active_rows` AS SELECT 1;");
        assert_eq!(postgres_with_drop, "CREATE VIEW active_rows AS SELECT 1;");
    }

    #[test]
    fn formats_sql_literals_for_export_inserts() {
        assert_eq!(format_export_sql_literal(&Value::Null), "NULL");
        assert_eq!(format_export_sql_literal(&json!(42)), "42");
        assert_eq!(format_export_sql_literal(&json!(true)), "TRUE");
        assert_eq!(format_export_sql_literal(&json!("O'Hara")), "'O''Hara'");
    }

    #[test]
    fn mysql_spatial_export_uses_wkb_constructor_and_preserves_srid() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Mysql),
            identifier_quote: None,
            schema: None,
            table_name: Some("places".to_string()),
            qualified_table_name: None,
            columns: vec!["location".to_string(), "shape".to_string()],
            column_types: vec![Some("point".to_string()), Some("geometry".to_string())],
            column_extras: Vec::new(),
            rows: vec![vec![
                json!("DBX_WKB:4326:0101000000AE47E17A14AE5C4052B81E85EBF34240"),
                json!("DBX_WKB:0:0101000000000000000000F03F0000000000000040"),
            ]],
            batch_size: Some(10),
        })
        .unwrap();

        assert_eq!(
            statements,
            vec!["INSERT INTO `places` (`location`, `shape`) VALUES (ST_GeomFromWKB(0x0101000000AE47E17A14AE5C4052B81E85EBF34240, 4326), ST_GeomFromWKB(0x0101000000000000000000F03F0000000000000040));"]
        );
    }

    #[test]
    fn mysql_spatial_export_rejects_markers_for_unknown_or_nonspatial_types() {
        let marker = json!("DBX_WKB:4326:0101000000AE47E17A14AE5C4052B81E85EBF34240");
        assert!(format_mysql_spatial_export_literal(&marker, Some(DatabaseType::Mysql), None).is_none());
        assert!(format_mysql_spatial_export_literal(&marker, Some(DatabaseType::Mysql), Some("varchar")).is_none());
        assert!(format_mysql_spatial_export_literal(
            &json!("DBX_WKB:4326:0101000000"),
            Some(DatabaseType::Mysql),
            Some("geometry"),
        )
        .is_none());
    }

    #[test]
    fn mysql_spatial_export_select_normalizes_geometry_columns_to_wkb_markers() {
        let sql = database_export_select_sql(
            &["id".to_string(), "location".to_string(), "name".to_string()],
            &[Some("int".to_string()), Some("point".to_string()), Some("varchar(32)".to_string())],
            "places",
            "app",
            &DatabaseType::Mysql,
        );

        assert_eq!(
            sql,
            "SELECT `id`, CASE WHEN `location` IS NULL THEN NULL ELSE CONCAT('DBX_WKB:', ST_SRID(`location`), ':', HEX(ST_AsWKB(`location`))) END AS `location`, `name` FROM `places`"
        );
    }

    #[test]
    fn mysql_spatial_export_keeps_keyset_pagination_when_replacing_select_list() {
        let columns = vec!["id".to_string(), "location".to_string()];
        let column_types = vec![Some("bigint".to_string()), Some("geometry".to_string())];
        let sql = crate::transfer::keyset_pagination_sql_with_identifier_quote(
            &columns,
            "places",
            "app",
            &DatabaseType::Mysql,
            &["id".to_string()],
            &[json!(7)],
            1000,
            None,
        );

        let sql = replace_database_export_select_list(sql, &columns, &column_types, &DatabaseType::Mysql);

        assert!(sql.starts_with(
            "SELECT `id`, CASE WHEN `location` IS NULL THEN NULL ELSE CONCAT('DBX_WKB:', ST_SRID(`location`), ':', HEX(ST_AsWKB(`location`))) END AS `location` FROM `places`"
        ));
        assert!(sql.contains("WHERE `id` > 7"), "sql: {sql}");
        assert!(sql.contains("ORDER BY `id` ASC LIMIT 1000"), "sql: {sql}");
    }

    #[test]
    fn database_specific_boolean_export_literals() {
        let sqlserver_statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::SqlServer),
            identifier_quote: None,
            schema: Some("dbo".to_string()),
            table_name: Some("flags".to_string()),
            qualified_table_name: None,
            columns: vec!["typed_true".to_string(), "untyped_false".to_string(), "typed_null".to_string()],
            column_types: vec![Some("bit".to_string()), None, Some("bit".to_string())],
            column_extras: Vec::new(),
            rows: vec![vec![json!(true), json!(false), Value::Null]],
            batch_size: Some(10),
        })
        .unwrap();
        let postgres_statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Postgres),
            identifier_quote: None,
            schema: Some("public".to_string()),
            table_name: Some("flags".to_string()),
            qualified_table_name: None,
            columns: vec!["enabled".to_string(), "disabled".to_string(), "unknown".to_string()],
            column_types: Vec::new(),
            column_extras: Vec::new(),
            rows: vec![vec![json!(true), json!(false), Value::Null]],
            batch_size: Some(10),
        })
        .unwrap();

        assert_eq!(
            sqlserver_statements,
            vec!["INSERT INTO [dbo].[flags] ([typed_true], [untyped_false], [typed_null]) VALUES (1, 0, NULL);"]
        );
        assert_eq!(
            postgres_statements,
            vec![
                "INSERT INTO \"public\".\"flags\" (\"enabled\", \"disabled\", \"unknown\") VALUES (TRUE, FALSE, NULL);"
            ]
        );
    }

    #[test]
    fn sqlserver_export_prefixes_unicode_string_literals() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::SqlServer),
            identifier_quote: None,
            schema: Some("dbo".to_string()),
            table_name: Some("people".to_string()),
            qualified_table_name: None,
            columns: vec![
                "name".to_string(),
                "code".to_string(),
                "legacy_note".to_string(),
                "alias_name".to_string(),
                "plain_text".to_string(),
                "missing".to_string(),
            ],
            column_types: vec![
                Some("NVARCHAR(255)".to_string()),
                Some(" nchar (10) ".to_string()),
                Some("ntext".to_string()),
                Some("sysname".to_string()),
                Some("varchar(255)".to_string()),
                Some("nvarchar(20)".to_string()),
            ],
            column_extras: Vec::new(),
            rows: vec![vec![
                json!("张'三"),
                json!("中文"),
                json!("旧文本"),
                json!("别名"),
                json!("plain"),
                Value::Null,
            ]],
            batch_size: Some(10),
        })
        .unwrap();

        assert_eq!(
            statements,
            vec![
                "INSERT INTO [dbo].[people] ([name], [code], [legacy_note], [alias_name], [plain_text], [missing]) VALUES (N'张''三', N'中文', N'旧文本', N'别名', 'plain', NULL);"
            ]
        );
    }

    #[test]
    fn mysql_export_inserts_escape_control_characters() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Mysql),
            identifier_quote: None,
            schema: None,
            table_name: Some("notes".to_string()),
            qualified_table_name: None,
            columns: vec!["body".to_string()],
            column_types: vec![Some("text".to_string())],
            column_extras: Vec::new(),
            rows: vec![vec![json!("line1\nline2\tcol\rend\\slash\0\x1aO'Hara")]],
            batch_size: Some(10),
        })
        .unwrap();

        assert_eq!(
            statements,
            vec!["INSERT INTO `notes` (`body`) VALUES ('line1\\nline2\\tcol\\rend\\\\slash\\0\\ZO''Hara');"]
        );
    }

    #[test]
    fn export_insert_batches_split_on_statement_bytes() {
        let long_value = "x".repeat(300_000);
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Mysql),
            identifier_quote: None,
            schema: None,
            table_name: Some("payloads".to_string()),
            qualified_table_name: None,
            columns: vec!["payload".to_string()],
            column_types: vec![Some("longtext".to_string())],
            column_extras: Vec::new(),
            rows: vec![vec![json!(long_value.clone())], vec![json!(long_value)]],
            batch_size: Some(100),
        })
        .unwrap();

        assert_eq!(statements.len(), 2);
        assert!(statements.iter().all(|statement| statement.matches("INSERT INTO").count() == 1));
    }

    #[test]
    fn sqlserver_export_caps_multi_row_insert_at_1000_rows() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::SqlServer),
            identifier_quote: None,
            schema: Some("dbo".to_string()),
            table_name: Some("items".to_string()),
            qualified_table_name: None,
            columns: vec!["id".to_string()],
            column_types: vec![Some("int".to_string())],
            column_extras: Vec::new(),
            rows: (0..1001).map(|id| vec![json!(id)]).collect(),
            batch_size: Some(2000),
        })
        .unwrap();

        assert_eq!(statements.len(), 2);
        assert_eq!(statements[0].matches("), (").count(), 999);
        assert_eq!(statements[1].matches("), (").count(), 0);
    }

    #[test]
    fn doris_export_inserts_escape_control_characters() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Doris),
            identifier_quote: None,
            schema: Some("warehouse".to_string()),
            table_name: Some("events".to_string()),
            qualified_table_name: None,
            columns: vec!["message".to_string()],
            column_types: vec![Some("varchar(255)".to_string())],
            column_extras: Vec::new(),
            rows: vec![vec![json!("first\nsecond\tthird")]],
            batch_size: Some(10),
        })
        .unwrap();

        assert_eq!(statements, vec!["INSERT INTO `warehouse`.`events` (`message`) VALUES ('first\\nsecond\\tthird');"]);
    }

    #[test]
    fn postgres_export_inserts_escape_control_characters() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Postgres),
            identifier_quote: None,
            schema: Some("public".to_string()),
            table_name: Some("notes".to_string()),
            qualified_table_name: None,
            columns: vec!["body".to_string()],
            column_types: vec![Some("text".to_string())],
            column_extras: Vec::new(),
            rows: vec![vec![json!("line1\nline2\tend")]],
            batch_size: Some(10),
        })
        .unwrap();

        assert_eq!(statements, vec!["INSERT INTO \"public\".\"notes\" (\"body\") VALUES (E'line1\\nline2\\tend');"]);
    }

    #[test]
    fn postgres_export_inserts_escape_quotes_and_backslashes_without_changing_plain_strings() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Postgres),
            identifier_quote: None,
            schema: Some("public".to_string()),
            table_name: Some("notes".to_string()),
            qualified_table_name: None,
            columns: vec!["carriage_return".to_string(), "quote".to_string(), "path".to_string(), "plain".to_string()],
            column_types: vec![
                Some("text".to_string()),
                Some("text".to_string()),
                Some("text".to_string()),
                Some("text".to_string()),
            ],
            column_extras: Vec::new(),
            rows: vec![vec![json!("line1\rline2"), json!("O'Hara"), json!(r"C:\tmp"), json!("plain")]],
            batch_size: Some(10),
        })
        .unwrap();

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

    #[test]
    fn postgres_jsonb_export_preserves_json_escape_sequences() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Postgres),
            identifier_quote: None,
            schema: Some("public".to_string()),
            table_name: Some("events".to_string()),
            qualified_table_name: None,
            columns: vec!["payload".to_string()],
            column_types: vec![Some("jsonb".to_string())],
            column_extras: Vec::new(),
            rows: vec![vec![json!(r#"{"text":"say \"hi\"","path":"C:\\tmp","quote":"O'Hara"}"#)]],
            batch_size: Some(10),
        })
        .unwrap();

        assert_eq!(
            statements,
            vec![
                r#"INSERT INTO "public"."events" ("payload") VALUES (E'{"text":"say \\"hi\\"","path":"C:\\\\tmp","quote":"O''Hara"}');"#
            ]
        );
    }

    #[test]
    fn postgres_vector_export_preserves_pgvector_bracket_literals() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Postgres),
            identifier_quote: None,
            schema: Some("public".to_string()),
            table_name: Some("items".to_string()),
            qualified_table_name: None,
            columns: vec![
                "id".to_string(),
                "embedding".to_string(),
                "qualified_embedding".to_string(),
                "labels".to_string(),
            ],
            column_types: vec![
                Some("integer".to_string()),
                Some("vector(2)".to_string()),
                Some("public.vector".to_string()),
                Some("text[]".to_string()),
            ],
            column_extras: Vec::new(),
            rows: vec![vec![json!(1), json!([1.2, 3.4]), json!(["5", "6"]), json!(["x", "y"])]],
            batch_size: Some(10),
        })
        .unwrap();

        assert_eq!(
            statements,
            vec![
                r#"INSERT INTO "public"."items" ("id", "embedding", "qualified_embedding", "labels") VALUES (1, '[1.2,3.4]', '[5,6]', '{"x","y"}');"#
            ]
        );
    }

    #[test]
    fn builds_batched_insert_statements_for_export() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Mysql),
            identifier_quote: None,
            schema: None,
            table_name: Some("users".to_string()),
            qualified_table_name: None,
            columns: vec!["id".to_string(), "name".to_string()],
            column_types: Vec::new(),
            column_extras: Vec::new(),
            rows: vec![vec![json!(1), json!("Ada")], vec![json!(2), json!("O'Hara")], vec![json!(3), json!("Linus")]],
            batch_size: Some(2),
        })
        .unwrap();

        assert_eq!(
            statements,
            vec![
                "INSERT INTO `users` (`id`, `name`) VALUES (1, 'Ada'), (2, 'O''Hara');",
                "INSERT INTO `users` (`id`, `name`) VALUES (3, 'Linus');",
            ]
        );
    }

    #[test]
    fn oracle_export_inserts_use_one_statement_per_row() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Oracle),
            identifier_quote: None,
            schema: Some("APP".to_string()),
            table_name: Some("USERS".to_string()),
            qualified_table_name: None,
            columns: vec!["ID".to_string(), "NAME".to_string()],
            column_types: Vec::new(),
            column_extras: Vec::new(),
            rows: vec![vec![json!(1), json!("Ada")], vec![json!(2), json!("Linus")]],
            batch_size: Some(100),
        })
        .unwrap();

        assert_eq!(
            statements,
            vec![
                "INSERT INTO \"APP\".\"USERS\" (\"ID\", \"NAME\") VALUES (1, 'Ada');",
                "INSERT INTO \"APP\".\"USERS\" (\"ID\", \"NAME\") VALUES (2, 'Linus');",
            ]
        );
    }

    #[test]
    fn oracle_export_omits_synthetic_rowid_from_insert_columns() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Oracle),
            identifier_quote: None,
            schema: Some("APP".to_string()),
            table_name: Some("USERS".to_string()),
            qualified_table_name: None,
            columns: vec!["__DBX_ROWID".to_string(), "ID".to_string(), "NAME".to_string()],
            column_types: vec![Some("VARCHAR2".to_string()), Some("NUMBER".to_string()), Some("VARCHAR2".to_string())],
            column_extras: Vec::new(),
            rows: vec![vec![json!("AAAPr9AAEAAAAGfAAA"), json!(1), json!("Ada")]],
            batch_size: Some(100),
        })
        .unwrap();

        assert_eq!(statements, vec!["INSERT INTO \"APP\".\"USERS\" (\"ID\", \"NAME\") VALUES (1, 'Ada');"]);
    }

    #[test]
    fn oceanbase_oracle_export_omits_synthetic_rowid_from_insert_columns() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::OceanbaseOracle),
            identifier_quote: None,
            schema: Some("APP".to_string()),
            table_name: Some("USERS".to_string()),
            qualified_table_name: None,
            columns: vec!["__DBX_ROWID".to_string(), "ID".to_string(), "NAME".to_string()],
            column_types: vec![Some("VARCHAR2".to_string()), Some("NUMBER".to_string()), Some("VARCHAR2".to_string())],
            column_extras: Vec::new(),
            rows: vec![vec![json!("*AAABk1AAEAAAAAgAAA"), json!(1), json!("Ada")]],
            batch_size: Some(100),
        })
        .unwrap();

        assert_eq!(statements, vec!["INSERT INTO \"APP\".\"USERS\" (\"ID\", \"NAME\") VALUES (1, 'Ada');"]);
    }

    #[test]
    fn non_oracle_export_preserves_dbx_rowid_named_column() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Mysql),
            identifier_quote: None,
            schema: None,
            table_name: Some("users".to_string()),
            qualified_table_name: None,
            columns: vec!["__DBX_ROWID".to_string(), "name".to_string()],
            column_types: Vec::new(),
            column_extras: Vec::new(),
            rows: vec![vec![json!(7), json!("Ada")]],
            batch_size: Some(100),
        })
        .unwrap();

        assert_eq!(statements, vec!["INSERT INTO `users` (`__DBX_ROWID`, `name`) VALUES (7, 'Ada');"]);
    }

    #[test]
    fn oracle_date_columns_export_as_date_literals() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Oracle),
            identifier_quote: None,
            schema: Some("APP".to_string()),
            table_name: Some("EVENTS".to_string()),
            qualified_table_name: None,
            columns: vec!["ID".to_string(), "CREATED_ON".to_string(), "RAW_TEXT".to_string()],
            column_types: vec![Some("NUMBER".to_string()), Some("DATE".to_string()), Some("VARCHAR2(64)".to_string())],
            column_extras: Vec::new(),
            rows: vec![
                vec![json!(1), json!("2022-08-25T09:58:43Z"), json!("2022-08-25T09:58:43Z")],
                vec![json!(2), json!("2022-08-25T00:00:00Z"), json!("2022-08-25T00:00:00Z")],
            ],
            batch_size: Some(100),
        })
        .unwrap();

        assert_eq!(
            statements,
            vec![
                "INSERT INTO \"APP\".\"EVENTS\" (\"ID\", \"CREATED_ON\", \"RAW_TEXT\") VALUES (1, TO_DATE('2022-08-25 09:58:43', 'YYYY-MM-DD HH24:MI:SS'), '2022-08-25T09:58:43Z');",
                "INSERT INTO \"APP\".\"EVENTS\" (\"ID\", \"CREATED_ON\", \"RAW_TEXT\") VALUES (2, DATE '2022-08-25', '2022-08-25T00:00:00Z');",
            ]
        );
    }

    #[test]
    fn oracle_timestamp_columns_export_as_explicit_literals() {
        for database_type in [DatabaseType::Oracle, DatabaseType::OceanbaseOracle] {
            let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
                database_type: Some(database_type),
                identifier_quote: None,
                schema: Some("APP".to_string()),
                table_name: Some("EVENTS".to_string()),
                qualified_table_name: None,
                columns: vec![
                    "CREATED_AT".to_string(),
                    "UPDATED_AT".to_string(),
                    "RECORDED_AT".to_string(),
                    "LOCAL_RECORDED_AT".to_string(),
                    "DRIVER_CREATED_AT".to_string(),
                    "DRIVER_RECORDED_AT".to_string(),
                    "RAW_TEXT".to_string(),
                    "UNTYPED".to_string(),
                    "INVALID_AT".to_string(),
                    "SHAPED_INVALID_AT".to_string(),
                    "NULL_AT".to_string(),
                ],
                column_types: vec![
                    Some("TIMESTAMP(6)".to_string()),
                    Some("TIMESTAMP(6)".to_string()),
                    Some("TIMESTAMP(9) WITH TIME ZONE".to_string()),
                    Some("TIMESTAMP(6) WITH LOCAL TIME ZONE".to_string()),
                    Some("TimeStampDTY".to_string()),
                    Some("TimeStampTZ_DTY".to_string()),
                    Some("VARCHAR2(64)".to_string()),
                    None,
                    Some("TIMESTAMP(6)".to_string()),
                    Some("TIMESTAMP(6)".to_string()),
                    Some("TIMESTAMP".to_string()),
                ],
                column_extras: Vec::new(),
                rows: vec![vec![
                    json!("2022-08-25 09:58:43.123456"),
                    json!("2022-08-26T10:59:44Z"),
                    json!("2022-08-27T11:00:45.123456789+08:00"),
                    json!("2022-08-28T12:01:46Z"),
                    json!("2022-08-29T13:02:47.123456"),
                    json!("2022-08-30T14:03:48-05:30"),
                    json!("2022-08-31T15:04:49Z"),
                    json!("2022-09-01T16:05:50Z"),
                    json!("not-a-timestamp"),
                    json!("2022-0'-25T09:58:43Z"),
                    Value::Null,
                ]],
                batch_size: Some(100),
            })
            .unwrap();

            assert_eq!(
                statements,
                vec![concat!(
                    "INSERT INTO \"APP\".\"EVENTS\" (\"CREATED_AT\", \"UPDATED_AT\", \"RECORDED_AT\", ",
                    "\"LOCAL_RECORDED_AT\", \"DRIVER_CREATED_AT\", \"DRIVER_RECORDED_AT\", \"RAW_TEXT\", ",
                    "\"UNTYPED\", \"INVALID_AT\", \"SHAPED_INVALID_AT\", \"NULL_AT\") VALUES ",
                    "(TO_TIMESTAMP('2022-08-25 09:58:43.123456', 'YYYY-MM-DD HH24:MI:SS.FF'), ",
                    "TO_TIMESTAMP('2022-08-26 10:59:44', 'YYYY-MM-DD HH24:MI:SS'), ",
                    "TO_TIMESTAMP_TZ('2022-08-27 11:00:45.123456789 +08:00', ",
                    "'YYYY-MM-DD HH24:MI:SS.FF TZH:TZM'), ",
                    "TO_TIMESTAMP_TZ('2022-08-28 12:01:46 +00:00', 'YYYY-MM-DD HH24:MI:SS TZH:TZM'), ",
                    "TO_TIMESTAMP('2022-08-29 13:02:47.123456', 'YYYY-MM-DD HH24:MI:SS.FF'), ",
                    "TO_TIMESTAMP_TZ('2022-08-30 14:03:48 -05:30', 'YYYY-MM-DD HH24:MI:SS TZH:TZM'), ",
                    "'2022-08-31T15:04:49Z', '2022-09-01T16:05:50Z', 'not-a-timestamp', ",
                    "'2022-0''-25T09:58:43Z', NULL);"
                )]
            );
        }
    }

    #[test]
    fn non_oracle_timestamp_exports_keep_existing_literals() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Postgres),
            identifier_quote: None,
            schema: Some("public".to_string()),
            table_name: Some("events".to_string()),
            qualified_table_name: None,
            columns: vec!["created_at".to_string(), "recorded_at".to_string()],
            column_types: vec![Some("timestamp".to_string()), Some("timestamp with time zone".to_string())],
            column_extras: Vec::new(),
            rows: vec![vec![json!("2022-08-25T09:58:43.123456Z"), json!("2022-08-26T10:59:44+08:00")]],
            batch_size: Some(100),
        })
        .unwrap();

        assert_eq!(
            statements,
            vec![concat!(
                "INSERT INTO \"public\".\"events\" (\"created_at\", \"recorded_at\") VALUES ",
                "('2022-08-25 09:58:43.123456', '2022-08-26 10:59:44+08:00');"
            )]
        );
    }

    #[test]
    fn mysql_bit_columns_export_without_quoted_string_values() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Mysql),
            identifier_quote: None,
            schema: None,
            table_name: Some("flags".to_string()),
            qualified_table_name: None,
            columns: vec!["enabled".to_string(), "mask".to_string(), "label".to_string()],
            column_types: vec![Some("bit(1)".to_string()), Some("BIT(4)".to_string()), Some("varchar(20)".to_string())],
            column_extras: Vec::new(),
            rows: vec![vec![json!("1"), json!("1010"), json!("1010")], vec![json!(false), json!(3), json!("off")]],
            batch_size: Some(10),
        })
        .unwrap();

        assert_eq!(
            statements,
            vec!["INSERT INTO `flags` (`enabled`, `mask`, `label`) VALUES (b'1', b'1010', '1010'), (b'0', 3, 'off');"]
        );
    }

    #[test]
    fn dameng_bit_columns_export_as_numeric_literals() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Dameng),
            identifier_quote: None,
            schema: Some("DBX_TEST".to_string()),
            table_name: Some("FLAGS".to_string()),
            qualified_table_name: None,
            columns: vec!["ENABLED".to_string(), "DELETED".to_string(), "OPTIONAL".to_string()],
            column_types: vec![Some("BIT".to_string()), Some("bit".to_string()), Some("BIT".to_string())],
            column_extras: Vec::new(),
            rows: vec![vec![json!(true), json!(false), Value::Null]],
            batch_size: Some(10),
        })
        .unwrap();

        assert_eq!(
            statements,
            vec!["INSERT INTO \"DBX_TEST\".\"FLAGS\" (\"ENABLED\", \"DELETED\", \"OPTIONAL\") VALUES (1, 0, NULL);"]
        );
    }

    #[test]
    fn dameng_strings_export_nul_as_chr_expression() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Dameng),
            identifier_quote: None,
            schema: Some("DBX_TEST".to_string()),
            table_name: Some("NUL_VALUES".to_string()),
            qualified_table_name: None,
            columns: vec![
                "PLAIN".to_string(),
                "TRAILING".to_string(),
                "LEADING".to_string(),
                "MIDDLE".to_string(),
                "CONSECUTIVE".to_string(),
                "ONLY_NUL".to_string(),
            ],
            column_types: vec![Some("VARCHAR".to_string()); 6],
            column_extras: Vec::new(),
            rows: vec![vec![
                json!("plain"),
                json!("eHall\0"),
                json!("\0leading"),
                json!("left\0right"),
                json!("left\0\0right"),
                json!("\0"),
            ]],
            batch_size: Some(10),
        })
        .unwrap();

        assert_eq!(
            statements,
            vec![concat!(
                "INSERT INTO \"DBX_TEST\".\"NUL_VALUES\" ",
                "(\"PLAIN\", \"TRAILING\", \"LEADING\", \"MIDDLE\", \"CONSECUTIVE\", \"ONLY_NUL\") ",
                "VALUES ('plain', 'eHall' || CHR(0), CHR(0) || 'leading', 'left' || CHR(0) || 'right', ",
                "'left' || CHR(0) || CHR(0) || 'right', CHR(0));"
            )]
        );
        assert!(!statements[0].contains('\0'));
    }

    #[test]
    fn mysql_export_uses_typed_literals_for_numeric_and_blob_columns() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Mysql),
            identifier_quote: None,
            schema: None,
            table_name: Some("t_test_01".to_string()),
            qualified_table_name: None,
            columns: vec!["id".to_string(), "f_blob".to_string(), "note".to_string()],
            column_types: vec![Some("int".to_string()), Some("blob".to_string()), Some("varchar(64)".to_string())],
            column_extras: Vec::new(),
            rows: vec![
                vec![json!("1"), json!("0x68656c6c6f"), json!("0x68656c6c6f")],
                vec![json!("2"), json!("0X"), json!("1")],
            ],
            batch_size: Some(10),
        })
        .unwrap();

        assert_eq!(
            statements,
            vec![
                "INSERT INTO `t_test_01` (`id`, `f_blob`, `note`) VALUES (1, 0x68656c6c6f, '0x68656c6c6f'), (2, X'', '1');"
            ]
        );
    }

    #[test]
    fn temporal_columns_export_without_rfc3339_separator_or_utc_suffix() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Mysql),
            identifier_quote: None,
            schema: None,
            table_name: Some("events".to_string()),
            qualified_table_name: None,
            columns: vec!["id".to_string(), "created_at".to_string(), "created_on".to_string(), "raw_text".to_string()],
            column_types: vec![
                Some("int".to_string()),
                Some("timestamp".to_string()),
                Some("date".to_string()),
                Some("varchar(64)".to_string()),
            ],
            column_extras: Vec::new(),
            rows: vec![vec![
                json!(1),
                json!("2026-06-12T10:11:12.123456789Z"),
                json!("2026-06-12T10:11:12Z"),
                json!("2026-06-12T10:11:12Z"),
            ]],
            batch_size: Some(10),
        })
        .unwrap();

        assert_eq!(
            statements,
            vec![
                "INSERT INTO `events` (`id`, `created_at`, `created_on`, `raw_text`) VALUES (1, '2026-06-12 10:11:12.123456', '2026-06-12', '2026-06-12T10:11:12Z');"
            ]
        );
    }

    #[test]
    fn postgres_timestamptz_export_keeps_timezone_without_rfc3339_t_separator() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Postgres),
            identifier_quote: None,
            schema: Some("public".to_string()),
            table_name: Some("events".to_string()),
            qualified_table_name: None,
            columns: vec!["recorded_at".to_string(), "local_at".to_string()],
            column_types: vec![
                Some("timestamp with time zone".to_string()),
                Some("timestamp without time zone".to_string()),
            ],
            column_extras: Vec::new(),
            rows: vec![vec![json!("2026-06-12T10:11:12Z"), json!("2026-06-12T18:11:12+08:00")]],
            batch_size: Some(10),
        })
        .unwrap();

        assert_eq!(
            statements,
            vec![
                "INSERT INTO \"public\".\"events\" (\"recorded_at\", \"local_at\") VALUES ('2026-06-12 10:11:12+00:00', '2026-06-12 18:11:12');"
            ]
        );
    }

    #[test]
    fn sqlserver_rowversion_timestamp_type_is_not_treated_as_datetime() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::SqlServer),
            identifier_quote: None,
            schema: Some("dbo".to_string()),
            table_name: Some("events".to_string()),
            qualified_table_name: None,
            columns: vec!["row_version".to_string(), "created_at".to_string()],
            column_types: vec![Some("timestamp".to_string()), Some("datetime2(3)".to_string())],
            column_extras: Vec::new(),
            rows: vec![vec![json!("2026-06-12T10:11:12Z"), json!("2026-06-12T10:11:12.1234567Z")]],
            batch_size: Some(10),
        })
        .unwrap();

        assert_eq!(
            statements,
            vec![
                "INSERT INTO [dbo].[events] ([row_version], [created_at]) VALUES ('2026-06-12T10:11:12Z', '2026-06-12 10:11:12.123');"
            ]
        );
    }

    #[test]
    fn postgres_tsvector_columns_are_omitted_from_sql_insert_export() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Postgres),
            identifier_quote: None,
            schema: Some("public".to_string()),
            table_name: Some("articles".to_string()),
            qualified_table_name: None,
            columns: vec!["id".to_string(), "title".to_string(), "search_vector".to_string()],
            column_types: vec![Some("integer".to_string()), Some("text".to_string()), Some("tsvector".to_string())],
            column_extras: Vec::new(),
            rows: vec![vec![json!(1), json!("Hello"), json!("'hello':1A")]],
            batch_size: Some(10),
        })
        .unwrap();

        assert_eq!(statements, vec!["INSERT INTO \"public\".\"articles\" (\"id\", \"title\") VALUES (1, 'Hello');"]);
    }

    #[test]
    fn mysql_generated_columns_are_omitted_from_sql_inserts_but_kept_in_ddl() {
        let ddl = "CREATE TABLE `orders` (`id` bigint AUTO_INCREMENT, `quantity` int, `unit_price` decimal(10,2), `virtual_total` decimal(10,2) GENERATED ALWAYS AS ((`quantity` * `unit_price`)) VIRTUAL, `stored_total` decimal(10,2) GENERATED ALWAYS AS ((`quantity` * `unit_price`)) STORED);";
        let sql = build_database_sql_export(BuildDatabaseSqlExportOptions {
            database_name: "shop".to_string(),
            exported_at: Some("2026-07-30T00:00:00.000Z".to_string()),
            tables: vec![ExportedTableSql {
                display_name: "orders".to_string(),
                database_type: Some(DatabaseType::Mysql),
                identifier_quote: None,
                schema: None,
                table_name: Some("orders".to_string()),
                qualified_table_name: None,
                ddl: Some(ddl.to_string()),
                columns: vec![
                    "id".to_string(),
                    "quantity".to_string(),
                    "unit_price".to_string(),
                    "virtual_total".to_string(),
                    "stored_total".to_string(),
                    "created_at".to_string(),
                ],
                column_types: vec![
                    Some("bigint".to_string()),
                    Some("int".to_string()),
                    Some("decimal(10,2)".to_string()),
                    Some("decimal(10,2)".to_string()),
                    Some("decimal(10,2)".to_string()),
                    Some("timestamp".to_string()),
                ],
                column_extras: vec![
                    Some("auto_increment".to_string()),
                    None,
                    None,
                    Some("VIRTUAL GENERATED".to_string()),
                    Some("stored generated".to_string()),
                    Some("DEFAULT_GENERATED".to_string()),
                ],
                rows: vec![vec![json!(7), json!(2), json!(3.5), json!(7.0), json!(7.0), json!("2026-07-30 08:00:00")]],
                truncated: false,
            }],
            row_limit_per_table: Some(DATABASE_EXPORT_ROW_LIMIT),
            insert_batch_size: Some(DATABASE_EXPORT_INSERT_BATCH_SIZE),
            connection_id: None,
            database: None,
            schema: None,
            omit_auto_increment: false,
        })
        .unwrap();

        assert!(sql.contains(ddl));
        assert!(sql.contains(
            "INSERT INTO `orders` (`id`, `quantity`, `unit_price`, `created_at`) VALUES (7, 2, 3.5, '2026-07-30 08:00:00');"
        ));
        assert!(!sql.contains("INSERT INTO `orders` (`id`, `quantity`, `unit_price`, `virtual_total`"));
    }

    #[test]
    fn mysql_database_export_file_rows_omit_generated_columns() {
        let directory = tempfile::tempdir().unwrap();
        let path = directory.path().join("orders.sql");
        let mut file = std::fs::File::create(&path).unwrap();

        write_database_export_rows(
            &mut file,
            &[vec![json!(7), json!(2), json!(7.0), json!("2026-07-30 08:00:00")]],
            &["id".to_string(), "quantity".to_string(), "virtual_total".to_string(), "created_at".to_string()],
            &[
                Some("bigint".to_string()),
                Some("int".to_string()),
                Some("decimal(10,2)".to_string()),
                Some("timestamp".to_string()),
            ],
            &[
                Some("auto_increment".to_string()),
                None,
                Some("VIRTUAL GENERATED".to_string()),
                Some("DEFAULT_GENERATED".to_string()),
            ],
            "orders",
            "shop",
            &DatabaseType::Mysql,
        )
        .unwrap();
        drop(file);

        assert_eq!(
            std::fs::read_to_string(path).unwrap(),
            "INSERT INTO `orders` (`id`, `quantity`, `created_at`) VALUES (7, 2, '2026-07-30 08:00:00');\n\n"
        );
    }

    #[test]
    fn dameng_identity_export_inserts_enable_identity_insert() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Dameng),
            identifier_quote: None,
            schema: Some("SYSDBA".to_string()),
            table_name: Some("USERS".to_string()),
            qualified_table_name: None,
            columns: vec!["ID".to_string(), "NAME".to_string()],
            column_types: vec![Some("INT".to_string()), Some("VARCHAR(20)".to_string())],
            column_extras: vec![Some("identity".to_string()), None],
            rows: vec![vec![json!(1), json!("Ada")]],
            batch_size: Some(10),
        })
        .unwrap();

        assert_eq!(
            statements,
            vec![
                "SET IDENTITY_INSERT \"SYSDBA\".\"USERS\" ON;\nINSERT INTO \"SYSDBA\".\"USERS\" (\"ID\", \"NAME\") VALUES (1, 'Ada');\nSET IDENTITY_INSERT \"SYSDBA\".\"USERS\" OFF;"
            ]
        );
    }

    #[test]
    fn builds_database_sql_export_with_ddl_before_data() {
        let sql = build_database_sql_export(BuildDatabaseSqlExportOptions {
            database_name: "app".to_string(),
            exported_at: Some("2026-05-02T00:00:00.000Z".to_string()),
            tables: vec![ExportedTableSql {
                display_name: "users".to_string(),
                database_type: Some(DatabaseType::Mysql),
                identifier_quote: None,
                schema: None,
                table_name: Some("users".to_string()),
                qualified_table_name: None,
                ddl: Some("CREATE TABLE `users` (`id` int);".to_string()),
                columns: vec!["id".to_string()],
                column_types: Vec::new(),
                column_extras: Vec::new(),
                rows: vec![vec![json!(1)]],
                truncated: true,
            }],
            row_limit_per_table: Some(DATABASE_EXPORT_ROW_LIMIT),
            insert_batch_size: Some(DATABASE_EXPORT_INSERT_BATCH_SIZE),
            connection_id: None,
            database: None,
            schema: None,
            omit_auto_increment: false,
        })
        .unwrap();

        assert_eq!(
            sql,
            [
                "-- DBX database export".to_string(),
                "-- Database: app".to_string(),
                "-- Exported at: 2026-05-02T00:00:00.000Z".to_string(),
                format!("-- Row limit per table: {DATABASE_EXPORT_ROW_LIMIT}"),
                String::new(),
                "-- Structure for users".to_string(),
                "CREATE TABLE `users` (`id` int);".to_string(),
                String::new(),
                "-- Data for users".to_string(),
                format!("-- Exported rows: 1 (truncated at {DATABASE_EXPORT_ROW_LIMIT})"),
                "INSERT INTO `users` (`id`) VALUES (1);".to_string(),
                String::new(),
            ]
            .join("\n")
        );
    }

    #[test]
    fn table_ddl_export_has_one_statement_terminator() {
        let ddl = "CREATE TABLE `users` (`id` int);;\n";

        assert_eq!(
            format_export_table_ddl(ddl, Some(DatabaseType::Mysql), DdlNormalizeOptions::default()),
            "CREATE TABLE `users` (`id` int);"
        );
        assert_eq!(
            format_export_table_ddl(
                "CREATE TABLE users (id int)",
                Some(DatabaseType::Postgres),
                DdlNormalizeOptions::default(),
            ),
            "CREATE TABLE users (id int);"
        );
    }

    #[test]
    fn omitted_auto_increment_preserves_mysql_line_comment_boundaries() {
        let options = DdlNormalizeOptions { omit_auto_increment: true };

        assert_eq!(
            format_export_table_ddl(
                "CREATE TABLE `users` (`id` int) ENGINE=InnoDB -- keep this comment\nAUTO_INCREMENT=5 DEFAULT CHARSET=utf8mb4",
                Some(DatabaseType::Mysql),
                options,
            ),
            "CREATE TABLE `users` (`id` int) ENGINE=InnoDB -- keep this comment\n DEFAULT CHARSET=utf8mb4;"
        );
        assert_eq!(
            format_export_table_ddl(
                "CREATE TABLE `users` (`id` int) ENGINE=InnoDB # keep this comment\r\nAUTO_INCREMENT=5 DEFAULT CHARSET=utf8mb4",
                Some(DatabaseType::Mysql),
                options,
            ),
            "CREATE TABLE `users` (`id` int) ENGINE=InnoDB # keep this comment\r\n DEFAULT CHARSET=utf8mb4;"
        );
    }

    #[test]
    fn omitted_auto_increment_consumes_only_horizontal_separator_whitespace() {
        let options = DdlNormalizeOptions { omit_auto_increment: true };

        for separator in [" ", "\t"] {
            let ddl = format!(
                "CREATE TABLE `users` (`id` int) ENGINE=InnoDB{separator}AUTO_INCREMENT=5 DEFAULT CHARSET=utf8mb4"
            );
            assert_eq!(
                format_export_table_ddl(&ddl, Some(DatabaseType::Mysql), options),
                "CREATE TABLE `users` (`id` int) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;"
            );
        }
    }

    #[test]
    fn normalizes_legacy_mysql_row_format_for_export_compatibility() {
        let ddl = "CREATE TABLE `wide_table` (\n  `payload` varchar(4096) DEFAULT NULL\n) ENGINE=InnoDB DEFAULT CHARSET=utf8 ROW_FORMAT=COMPACT";

        let normalized = normalize_export_table_ddl(ddl, Some(DatabaseType::Mysql), DdlNormalizeOptions::default());

        assert_eq!(
            normalized,
            "CREATE TABLE `wide_table` (\n  `payload` varchar(4096) DEFAULT NULL\n) ENGINE=InnoDB DEFAULT CHARSET=utf8 ROW_FORMAT=DYNAMIC"
        );
    }

    #[test]
    fn normalizes_lowercase_redundant_mysql_row_format_for_export_compatibility() {
        let ddl = "CREATE TABLE `wide_table` (`payload` varchar(4096)) engine=InnoDB row_format = redundant";

        let normalized = normalize_export_table_ddl(ddl, Some(DatabaseType::Mysql), DdlNormalizeOptions::default());

        assert_eq!(normalized, "CREATE TABLE `wide_table` (`payload` varchar(4096)) engine=InnoDB ROW_FORMAT=DYNAMIC");
    }

    #[test]
    fn preserves_non_legacy_or_non_mysql_row_formats() {
        let mysql_ddl = "CREATE TABLE `ok` (`payload` text) ENGINE=InnoDB ROW_FORMAT=COMPRESSED";
        let postgres_ddl = "CREATE TABLE users (payload text) ROW_FORMAT=COMPACT";

        assert_eq!(
            normalize_export_table_ddl(mysql_ddl, Some(DatabaseType::Mysql), DdlNormalizeOptions::default()),
            mysql_ddl
        );
        assert_eq!(
            normalize_export_table_ddl(postgres_ddl, Some(DatabaseType::Postgres), DdlNormalizeOptions::default()),
            postgres_ddl
        );
    }

    fn postgres_sequence(name: &str) -> PostgresExportSequence {
        PostgresExportSequence {
            name: name.to_string(),
            data_type: "integer".to_string(),
            start_value: "1".to_string(),
            min_value: "1".to_string(),
            max_value: "2147483647".to_string(),
            increment: "1".to_string(),
            cycle: false,
            cache_value: "1".to_string(),
            last_value: Some("42".to_string()),
            owner_table: Some("permissions".to_string()),
            owner_column: Some("id".to_string()),
        }
    }

    #[test]
    fn postgres_sequence_create_ddl_is_importable_before_table_ddl() {
        let ddl = generate_postgres_sequence_create_ddl(&postgres_sequence("permissions_id_seq"), "public");

        assert_eq!(
            ddl,
            [
                "CREATE SEQUENCE IF NOT EXISTS \"public\".\"permissions_id_seq\"",
                "  AS integer",
                "  START WITH 1",
                "  INCREMENT BY 1",
                "  MINVALUE 1",
                "  MAXVALUE 2147483647",
                "  CACHE 1",
                "  NO CYCLE",
            ]
            .join("\n")
        );
    }

    #[test]
    fn postgres_sequence_owner_and_setval_sql_are_qualified() {
        let sequence = postgres_sequence("permissions_id_seq");

        assert_eq!(
            generate_postgres_sequence_owner_ddl(&sequence, "public").as_deref(),
            Some("ALTER SEQUENCE \"public\".\"permissions_id_seq\" OWNED BY \"public\".\"permissions\".\"id\"")
        );
        assert_eq!(
            generate_postgres_sequence_setval_sql(&sequence, "public").as_deref(),
            Some(
                "SELECT setval('\"public\".\"permissions_id_seq\"', GREATEST(COALESCE(MAX(\"id\"), 42), 42), true) FROM \"public\".\"permissions\""
            )
        );
    }

    #[test]
    fn strict_exports_return_object_errors_instead_of_writing_error_comments() {
        let path = std::env::temp_dir().join(format!("dbx-strict-export-{}.sql", uuid::Uuid::new_v4()));
        let mut file = std::fs::File::create(&path).unwrap();

        let result = record_export_error(&mut file, true, "exporting table users: permission denied".to_string());
        drop(file);

        assert_eq!(result.unwrap_err(), "exporting table users: permission denied");
        assert!(std::fs::read_to_string(&path).unwrap().is_empty());
        let _ = std::fs::remove_file(path);
    }

    async fn test_app_state(scratch_dir: &std::path::Path) -> AppState {
        let storage = Storage::open(&scratch_dir.join("storage.db")).await.unwrap();
        AppState::new(storage)
    }

    // Regression tests for #6327: create_dir_all on every export run is unsafe
    // when the destination is on a removable/network drive, because a mount
    // that is temporarily gone at write time would be silently recreated on
    // the local root filesystem, and the backup would "succeed" while writing
    // to the wrong disk.

    #[tokio::test]
    async fn ensure_export_destination_dir_creates_a_never_before_seen_local_directory() {
        let scratch = std::env::temp_dir().join(format!("dbx-export-dest-new-{}", uuid::Uuid::new_v4()));
        std::fs::create_dir_all(&scratch).unwrap();
        let state = test_app_state(&scratch).await;

        let destination = scratch.join("backups").join("mydb");
        assert!(!destination.exists());

        ensure_export_destination_dir(&state, &destination)
            .await
            .expect("first-time local directory should be created");
        assert!(destination.is_dir());

        let _ = std::fs::remove_dir_all(&scratch);
    }

    #[tokio::test]
    async fn ensure_export_destination_dir_refuses_to_recreate_a_destination_that_disappeared() {
        let scratch = std::env::temp_dir().join(format!("dbx-export-dest-vanished-{}", uuid::Uuid::new_v4()));
        std::fs::create_dir_all(&scratch).unwrap();
        let state = test_app_state(&scratch).await;

        // Simulates a previously configured, already-used backup destination
        // (e.g. on an external or network drive) by successfully exporting to
        // it once first.
        let destination = scratch.join("mounted-drive").join("mydb");
        ensure_export_destination_dir(&state, &destination).await.expect("initial export should create the directory");
        assert!(destination.is_dir());

        // Simulates the mount disappearing (unplugged drive, unmounted share,
        // etc.) before the next run.
        std::fs::remove_dir_all(scratch.join("mounted-drive")).unwrap();
        assert!(!destination.exists());

        let result = ensure_export_destination_dir(&state, &destination).await;

        assert!(result.is_err(), "a destination that existed before should not be silently recreated");
        assert!(!destination.exists(), "the backup directory must not be resurrected on the wrong filesystem");

        let _ = std::fs::remove_dir_all(&scratch);
    }

    // Regression test for review feedback on #6327: `ensure_export_destination_dir`
    // only remembered a destination *after* a successful export, so a mount
    // that was present when a schedule was configured but vanished before its
    // very first run looked identical to a brand-new local folder (no
    // recorded state either way) and got silently recreated on the local
    // disk. `record_export_destination_identity` closes that gap by letting
    // the schedule-configuration flow record the destination eagerly.
    #[tokio::test]
    async fn record_export_destination_identity_protects_a_mount_that_vanishes_before_its_first_run() {
        let scratch = std::env::temp_dir().join(format!("dbx-export-dest-eager-{}", uuid::Uuid::new_v4()));
        std::fs::create_dir_all(&scratch).unwrap();
        let state = test_app_state(&scratch).await;

        // Simulates the user picking an already-mounted external/network
        // drive in the schedule editor and saving the schedule -- the
        // directory exists at configuration time, but no export has run yet.
        let destination = scratch.join("mounted-drive").join("mydb");
        std::fs::create_dir_all(&destination).unwrap();
        record_export_destination_identity(&state, &destination)
            .await
            .expect("configuring the schedule should succeed");

        // The mount disappears before the scheduler ever runs this schedule
        // for the first time.
        std::fs::remove_dir_all(scratch.join("mounted-drive")).unwrap();
        assert!(!destination.exists());

        let result = ensure_export_destination_dir(&state, &destination).await;

        assert!(result.is_err(), "a mount that was recorded at configuration time must not be silently recreated");
        assert!(!destination.exists(), "the backup directory must not be resurrected on the wrong filesystem");

        let _ = std::fs::remove_dir_all(&scratch);
    }

    #[tokio::test]
    async fn record_export_destination_identity_rejects_a_directory_that_disappeared_before_save() {
        let scratch = std::env::temp_dir().join(format!("dbx-export-dest-eager-new-{}", uuid::Uuid::new_v4()));
        std::fs::create_dir_all(&scratch).unwrap();
        let state = test_app_state(&scratch).await;

        // The schedule editor only accepts an existing directory. If that
        // directory disappears before the save request reaches the backend,
        // the schedule must not be persisted without a recorded identity.
        let destination = scratch.join("backups").join("mydb");
        assert!(!destination.exists());
        let error = record_export_destination_identity(&state, &destination)
            .await
            .expect_err("a missing scheduled destination must be rejected");

        assert!(error.contains("does not exist or is not a directory"));
        assert!(!destination.exists());

        let _ = std::fs::remove_dir_all(&scratch);
    }

    // Regression test for review feedback on #6327: the directory identity
    // check and the later `File::create` are separate operations, so the
    // mount can disappear and be replaced by something else at the same path
    // in between. `export_destination_identity_mismatch` is the comparison
    // `export_database_sql_core` runs against the handle it actually opened;
    // exercised directly here since reproducing a real cross-filesystem swap
    // mid-write is not something a portable unit test can simulate.
    #[test]
    fn export_destination_identity_mismatch_detects_a_changed_device() {
        assert!(export_destination_identity_mismatch(Some(1), Some(2)));
        assert!(!export_destination_identity_mismatch(Some(1), Some(1)));
        assert!(
            !export_destination_identity_mismatch(None, Some(2)),
            "an unknown expected device has nothing to compare against"
        );
        assert!(
            export_destination_identity_mismatch(Some(1), None),
            "an opened file with unknown identity must not bypass a known expected device"
        );
        assert!(!export_destination_identity_mismatch(None, None));
    }

    // Regression test for review feedback on #6327: the non-Unix path used
    // to report no device identity at all, so replacing a Windows drive or
    // mount at the same path went undetected. This only runs on native
    // Windows (this repo's CI has no Windows job that executes `cargo test`,
    // only `cargo check`, so it is exercised locally by Windows contributors
    // and by the compile-check itself).
    #[cfg(windows)]
    #[test]
    fn export_destination_device_id_for_path_and_open_file_agree_on_windows() {
        let scratch = std::env::temp_dir().join(format!("dbx-export-dest-win-{}", uuid::Uuid::new_v4()));
        std::fs::create_dir_all(&scratch).unwrap();

        let dir_dev = super::export_destination_device_id_for_path(&scratch);
        assert!(dir_dev.is_some(), "a real local directory should report a volume serial number");

        let file_path = scratch.join("probe.txt");
        let file = std::fs::File::create(&file_path).unwrap();
        let file_dev = super::export_destination_device_id_for_file(&file);
        drop(file);

        assert_eq!(dir_dev, file_dev, "a file and its parent directory must resolve to the same volume");

        let _ = std::fs::remove_dir_all(&scratch);
    }

    #[test]
    fn kingbase_mysql_compat_export_insert_uses_backtick_identifiers() {
        let statements = build_export_insert_statements(BuildExportInsertStatementsOptions {
            database_type: Some(DatabaseType::Kingbase),
            identifier_quote: Some("`".to_string()),
            schema: Some("audit-schema".to_string()),
            table_name: Some("events".to_string()),
            qualified_table_name: None,
            columns: vec!["id".to_string(), "event_type".to_string()],
            column_types: vec![None, None],
            column_extras: vec![None, None],
            rows: vec![vec![json!(1), json!("login")]],
            batch_size: Some(100),
        })
        .unwrap();
        assert_eq!(statements, vec!["INSERT INTO `audit-schema`.`events` (`id`, `event_type`) VALUES (1, 'login');"]);
    }
}