fix: always schema-qualify table in COMMENT ON COLUMN (#502)

internal/diff/diff.go

@@ -2179,6 +2179,17 @@ func qualifyEntityNameMode(entitySchema, entityName, targetSchema string, qualif
 	return fmt.Sprintf("%s.%s", quotedSchema, quotedName)
 }
 
+// qualifyColumnCommentTable returns the table name for use in COMMENT ON COLUMN
+// statements. Like qualifyEntityNameMode, it omits the schema when the table is
+// in the target schema — unless the table name itself matches the target schema,
+// which would cause stripSchemaQualifications to strip the table qualifier.
+func qualifyColumnCommentTable(tableSchema, tableName, targetSchema string, qualifySchema bool) string {
+	if !qualifySchema && tableSchema == targetSchema && strings.EqualFold(tableName, targetSchema) {
+		return fmt.Sprintf("%s.%s", ir.QuoteIdentifier(tableSchema), ir.QuoteIdentifier(tableName))
+	}
+	return qualifyEntityNameMode(tableSchema, tableName, targetSchema, qualifySchema)
+}
+
 // quoteString properly quotes a string for SQL, handling single quotes
 func quoteString(s string) string {
 	// Escape single quotes by doubling them

internal/diff/table.go

@@ -456,7 +456,7 @@ func generateCreateTablesSQL(
 		// Add column comments
 		for _, column := range table.Columns {
 			if column.Comment != "" {
-				tableName := qualifyEntityNameMode(table.Schema, table.Name, targetSchema, collector.qualifySchema)
+				tableName := qualifyColumnCommentTable(table.Schema, table.Name, targetSchema, collector.qualifySchema)
 				sql := fmt.Sprintf("COMMENT ON COLUMN %s.%s IS %s;", tableName, ir.QuoteIdentifier(column.Name), quoteString(column.Comment))
 
 				// Create context for this statement
@@ -1134,7 +1134,7 @@ func (td *tableDiff) generateAlterTableStatements(targetSchema string, collector
 	// Add comments for new columns
 	for _, column := range td.AddedColumns {
 		if column.Comment != "" {
-			tableName := getTableNameWithSchema(td.Table.Schema, td.Table.Name, targetSchema)
+			tableName := qualifyColumnCommentTable(td.Table.Schema, td.Table.Name, targetSchema, false)
 			sql := fmt.Sprintf("COMMENT ON COLUMN %s.%s IS %s;", tableName, ir.QuoteIdentifier(column.Name), quoteString(column.Comment))
 
 			context := &diffContext{
@@ -1603,7 +1603,7 @@ func (td *tableDiff) generateAlterTableStatements(targetSchema string, collector
 	// Handle column comment changes
 	for _, colDiff := range td.ModifiedColumns {
 		if colDiff.Old.Comment != colDiff.New.Comment {
-			tableName := getTableNameWithSchema(td.Table.Schema, td.Table.Name, targetSchema)
+			tableName := qualifyColumnCommentTable(td.Table.Schema, td.Table.Name, targetSchema, false)
 			var sql string
 			if colDiff.New.Comment == "" {
 				sql = fmt.Sprintf("COMMENT ON COLUMN %s.%s IS NULL;", tableName, ir.QuoteIdentifier(colDiff.New.Name))

testdata/diff/comment/issue_502_column_comment_table_name_matches_schema/diff.sql

@@ -0,0 +1,3 @@
+COMMENT ON COLUMN public.public.id IS 'Primary key';
+
+COMMENT ON COLUMN public.public.name IS 'Display name';

testdata/diff/comment/issue_502_column_comment_table_name_matches_schema/new.sql

@@ -0,0 +1,7 @@
+CREATE TABLE public (
+    id SERIAL PRIMARY KEY,
+    name TEXT NOT NULL
+);
+
+COMMENT ON COLUMN public.public.id IS 'Primary key';
+COMMENT ON COLUMN public.public.name IS 'Display name';

testdata/diff/comment/issue_502_column_comment_table_name_matches_schema/old.sql

@@ -0,0 +1,4 @@
+CREATE TABLE public (
+    id SERIAL PRIMARY KEY,
+    name TEXT NOT NULL
+);

testdata/diff/comment/issue_502_column_comment_table_name_matches_schema/plan.json

@@ -0,0 +1,26 @@
+{
+  "version": "1.0.0",
+  "pgschema_version": "1.11.1",
+  "created_at": "1970-01-01T00:00:00Z",
+  "source_fingerprint": {
+    "hash": "c8aff322ec8a9d064fda21505117c0b296ba9669f7503ad7d8055d7f8f1f5ff7"
+  },
+  "groups": [
+    {
+      "steps": [
+        {
+          "sql": "COMMENT ON COLUMN public.public.id IS 'Primary key';",
+          "type": "table.column.comment",
+          "operation": "alter",
+          "path": "public.public.id"
+        },
+        {
+          "sql": "COMMENT ON COLUMN public.public.name IS 'Display name';",
+          "type": "table.column.comment",
+          "operation": "alter",
+          "path": "public.public.name"
+        }
+      ]
+    }
+  ]
+}

testdata/diff/comment/issue_502_column_comment_table_name_matches_schema/plan.sql

@@ -0,0 +1,3 @@
+COMMENT ON COLUMN public.public.id IS 'Primary key';
+
+COMMENT ON COLUMN public.public.name IS 'Display name';

testdata/diff/comment/issue_502_column_comment_table_name_matches_schema/plan.txt

@@ -0,0 +1,16 @@
+Plan: 1 to modify.
+
+Summary by type:
+  tables: 1 to modify
+
+Tables:
+  ~ public
+    ~ id (column.comment)
+    ~ name (column.comment)
+
+DDL to be executed:
+--------------------------------------------------
+
+COMMENT ON COLUMN public.public.id IS 'Primary key';
+
+COMMENT ON COLUMN public.public.name IS 'Display name';