fix(clickhouse): keep ALTER TABLE UPDATE mutations together

apps/desktop/src/lib/__tests__/sql/sqlStatementRanges.spec.ts

@@ -443,6 +443,44 @@ COMMENT = '测试';`;
     expect(rangeSqlTexts(executableStatementRanges(sql, "mysql"))).toEqual([sql.slice(0, -1)]);
   });
 
+  it("keeps issue #4045 ClickHouse ALTER TABLE UPDATE mutation together", () => {
+    const sql = `ALTER TABLE m2_db.history_data5
+UPDATE value = 14.06
+WHERE uuid IN (
+    SELECT uuid
+    FROM m2_db.pt_uuid_mapping
+    WHERE point_id = 'TEST_Location_1_L2_METER_2_AE_DIFF_H'
+)
+AND ts = toDateTime('2026-07-15 12:00:00');`;
+
+    expect(statementRangeAtCursor(sql, indexOf(sql, "ALTER"), "clickhouse")?.sql.trim()).toBe(sql.slice(0, -1));
+    expect(statementRangeAtCursor(sql, indexOf(sql, "UPDATE"), "clickhouse")?.sql.trim()).toBe(sql.slice(0, -1));
+    expect(rangeSqlTexts(executableStatementRanges(sql, "clickhouse"))).toEqual([sql.slice(0, -1)]);
+  });
+
+  it("keeps a simple ClickHouse ALTER TABLE UPDATE mutation together", () => {
+    const sql = "ALTER TABLE `events` ON CLUSTER 'analytics'\nUPDATE value = 1\nWHERE id = 42;";
+
+    expect(statementRangeAtCursor(sql, indexOf(sql, "UPDATE"), "clickhouse")?.sql.trim()).toBe(sql.slice(0, -1));
+    expect(rangeSqlTexts(executableStatementRanges(sql, "clickhouse"))).toEqual([sql.slice(0, -1)]);
+  });
+
+  it("separates statements after a ClickHouse ALTER TABLE UPDATE mutation", () => {
+    const mutation = "ALTER TABLE events\nUPDATE value = 1\nWHERE id = 42";
+    const sql = `${mutation};\nSELECT * FROM events;\nUPDATE audit SET processed = 1;`;
+
+    expect(rangeSqlTexts(executableStatementRanges(sql, "clickhouse"))).toEqual([mutation, "SELECT * FROM events", "UPDATE audit SET processed = 1"]);
+  });
+
+  it("does not merge independent UPDATE statements into other ALTER statements", () => {
+    const otherDatabaseSql = "ALTER TABLE events\nUPDATE audit SET processed = 1;";
+    const clickHouseSql = "ALTER TABLE events ADD COLUMN source String\nUPDATE audit SET processed = 1;";
+
+    expect(rangeSqlTexts(executableStatementRanges(otherDatabaseSql, "postgres"))).toEqual(["ALTER TABLE events", "UPDATE audit SET processed = 1"]);
+    expect(rangeSqlTexts(executableStatementRanges(otherDatabaseSql, "mysql"))).toEqual(["ALTER TABLE events", "UPDATE audit SET processed = 1"]);
+    expect(rangeSqlTexts(executableStatementRanges(clickHouseSql, "clickhouse"))).toEqual(["ALTER TABLE events ADD COLUMN source String", "UPDATE audit SET processed = 1"]);
+  });
+
   it("keeps insert-select with the INSERT statement", () => {
     const sql = "INSERT INTO archived_users (id, name)\nSELECT id, name FROM users\nUPDATE users SET archived = 1;";
     const range = statementRangeAtCursor(sql, indexOf(sql, "archived_users"));

apps/desktop/src/lib/sql/sqlStatementRanges.ts

@@ -246,6 +246,7 @@ const EXPLAIN_STATEMENT_KEYWORDS = new Set(["SELECT", "WITH", "INSERT", "UPDATE"
 const CREATE_BODY_KEYWORDS = new Set(["SELECT", "WITH", "BEGIN", "DECLARE"]);
 const INSERT_BODY_KEYWORDS = new Set(["SELECT", "WITH"]);
 const ALTER_BODY_KEYWORDS = new Set(["ADD", "ALTER", "COMMENT", "DROP", "MODIFY", "RENAME", "SET"]);
+const CLICKHOUSE_ALTER_TABLE_HEADER = /^ALTER\s+TABLE\s+(?:(?:[A-Za-z_][\w$]*|`(?:``|[^`])+`|"(?:""|[^"])+")\s*\.\s*)?(?:[A-Za-z_][\w$]*|`(?:``|[^`])+`|"(?:""|[^"])+")(?:\s+ON\s+CLUSTER\s+(?:[A-Za-z_][\w$]*|`(?:``|[^`])+`|"(?:""|[^"])+"|'(?:''|[^'])+'))?\s*$/i;
 const SET_OPERATION_KEYWORDS = new Set(["UNION", "INTERSECT", "EXCEPT", "MINUS"]);
 const SET_OPERATION_MODIFIER_KEYWORDS = new Set(["ALL", "DISTINCT"]);
 const ORACLE_LIKE_PL_SQL_DATABASES: ReadonlySet<DatabaseType> = new Set(["oracle", "dameng", "gaussdb", "yashandb", "oscar", "oceanbase-oracle"]);
@@ -682,6 +683,12 @@ function splitStatementRangeAtSoftStarts(sql: string, statement: RawStatement, d
       continue;
     }
 
+    if (currentBodyKeyword === "ALTER" && isClickHouseAlterTableUpdateContinuation(sql, boundaries[boundaries.length - 1].from, lineStart.from, lineStart.keyword, databaseType)) {
+      // ClickHouse mutations use UPDATE as the first ALTER TABLE action, not as
+      // a standalone statement. Keep this dialect-specific to preserve soft boundaries elsewhere.
+      continue;
+    }
+
     if (currentBodyKeyword === "ALTER" && ALTER_BODY_KEYWORDS.has(lineStart.keyword)) {
       continue;
     }
@@ -917,6 +924,11 @@ function isMysqlCreateTableOptionContinuation(sql: string, statementFrom: number
   return next === "=" || next === "'" || next === '"';
 }
 
+function isClickHouseAlterTableUpdateContinuation(sql: string, statementFrom: number, lineStartFrom: number, keyword: string, databaseType?: DatabaseType): boolean {
+  if (databaseType !== "clickhouse" || keyword !== "UPDATE") return false;
+  return CLICKHOUSE_ALTER_TABLE_HEADER.test(sql.slice(statementFrom, lineStartFrom));
+}
+
 function startsWithMysqlCreateTable(sql: string, statementFrom: number): boolean {
   const text = sql.slice(statementFrom, statementFrom + 256);
   return /^CREATE\s+(?:TEMPORARY\s+)?TABLE\b/i.test(text);