fix _ #340-1: do not use prepare for ddl

internal/client/driver/mysql/applier.go

@@ -859,14 +859,17 @@ func (a *Applier) initDBConnections() (err error) {
 		a.logger.Errorf("mysql.applier: Unexpected error on validateGrants, got %v", err)
 		return err
 	}
+	a.logger.Debugf("mysql.applier. after validateGrants")
 	if err := a.validateAndReadTimeZone(); err != nil {
 		return err
 	}
+	a.logger.Debugf("mysql.applier. after validateAndReadTimeZone")
 
 	if a.mysqlContext.ApproveHeterogeneous {
 		if err := a.createTableGtidExecutedV2(); err != nil {
 			return err
 		}
+		a.logger.Debugf("mysql.applier. after createTableGtidExecutedV2")
 
 		for i := range a.dbs {
 			a.dbs[i].PsDeleteExecutedGtid, err = a.dbs[i].Db.PrepareContext(context.Background(), fmt.Sprintf("delete from %v.%v where job_uuid = unhex('%s') and source_uuid = ?",
@@ -884,6 +887,7 @@ func (a *Applier) initDBConnections() (err error) {
 			}
 
 		}
+		a.logger.Debugf("mysql.applier. after prepare stmt for gtid_executed table")
 	}
 	/*if err := a.readCurrentBinlogCoordinates(); err != nil {
 		return err
@@ -986,12 +990,15 @@ func (a *Applier) createTableGtidExecutedV2() error {
 		g.DtleSchemaName, g.GtidExecutedTableV2)); nil == err && len(result) > 0 {
 		return nil
 	}
+	a.logger.Debugf("mysql.applier. after show gtid_executed table")
+
 	query := fmt.Sprintf(`
 			CREATE DATABASE IF NOT EXISTS %v;
 		`, g.DtleSchemaName)
-	if _, err := sql.Exec(a.db, query); err != nil {
+	if _, err := a.db.Exec(query); err != nil {
 		return err
 	}
+	a.logger.Debugf("mysql.applier. after create dtle schema")
 
 	query = fmt.Sprintf(`
 			CREATE TABLE IF NOT EXISTS %v.%v (
@@ -1000,9 +1007,10 @@ func (a *Applier) createTableGtidExecutedV2() error {
 				interval_gtid text NOT NULL COMMENT 'number of interval.'
 			);
 		`, g.DtleSchemaName, g.GtidExecutedTableV2)
-	if _, err := sql.Exec(a.db, query); err != nil {
+	if _, err := a.db.Exec(query); err != nil {
 		return err
 	}
+	a.logger.Debugf("mysql.applier. after create gtid_executed table")
 
 	return nil
 }

internal/client/driver/mysql/sql/sqlutils.go

@@ -328,37 +328,6 @@ func ExecNoPrepare(db *gosql.Conn, query string, args ...interface{}) (gosql.Res
 	return res, err
 }
 
-// ExecQuery executes given query using given args on given DB. It will safele prepare, execute and close
-// the statement.
-func execInternal(silent bool, db *gosql.DB, query string, args ...interface{}) (gosql.Result, error) {
-	var err error
-	defer func() {
-		if derr := recover(); derr != nil {
-			err = errors.New(fmt.Sprintf("execInternal unexpected error: %+v", derr))
-		}
-	}()
-
-	stmt, err := db.Prepare(query)
-	if err != nil {
-		return nil, err
-	}
-	defer stmt.Close()
-	var res gosql.Result
-	res, err = stmt.Exec(args...)
-	return res, err
-}
-
-// Exec executes given query using given args on given DB. It will safele prepare, execute and close
-// the statement.
-func Exec(db *gosql.DB, query string, args ...interface{}) (gosql.Result, error) {
-	return execInternal(false, db, query, args...)
-}
-
-// ExecSilently acts like Exec but does not report any error
-func ExecSilently(db *gosql.DB, query string, args ...interface{}) (gosql.Result, error) {
-	return execInternal(true, db, query, args...)
-}
-
 func InClauseStringValues(terms []string) string {
 	quoted := []string{}
 	for _, s := range terms {