fail if selectedColumns == ""

Author: dtunikov

flow/connectors/mysql/qrep.go

@@ -277,6 +277,10 @@ func (c *MySqlConnector) PullQRepRecords(
 	}
 
 	selectedColumns := buildSelectedColumns(tableSchema.Columns, config.Exclude)
+	if selectedColumns == "" {
+		return 0, 0, fmt.Errorf("no columns selected for watermark table %s (check Exclude configuration)", config.WatermarkTable)
+	}
+
 	parsedSrcTable, err := common.ParseTableIdentifier(config.WatermarkTable)
 	if err != nil {
 		c.logger.Error("unable to parse source table", slog.Any("error", err))

flow/e2e/clickhouse_mysql_test.go

@@ -2460,9 +2460,6 @@ func (s ClickHouseSuite) Test_MySQL_GIPK_Consistency() {
 	srcFullName := s.attachSchemaSuffix(srcTableName)
 	dstTableName := "test_my_gipk_dst"
 
-	// GIPK is controlled by a session variable; the connector holds a single persistent connection,
-	// so the setting sticks for the subsequent CREATE. Reset it afterwards to avoid leaking into
-	// other tables in the suite.
 	require.NoError(s.t, s.source.Exec(s.t.Context(), `SET SESSION sql_generate_invisible_primary_key = ON`))
 	require.NoError(s.t, s.source.Exec(s.t.Context(), fmt.Sprintf(`
 		CREATE TABLE IF NOT EXISTS %s (