make everything same as before if no sql-mode in config file

cmd/drainer/drainer.toml

@@ -27,9 +27,10 @@ compressor = ""
 # syncer Configuration.
 [syncer]
 
-# Assume the upstream sql-mode, will use the same sql-mode to parse DDL statment, and set the same sql-mode at downstream
-# when db-type is mysql
-sql-mode = "STRICT_TRANS_TABLES,NO_ENGINE_SUBSTITUTION"
+# Assume the upstream sql-mode.
+# If this is setted , will use the same sql-mode to parse DDL statment, and set the same sql-mode at downstream when db-type is mysql.
+# If this is not setted, it will not set any sql-mode.
+# sql-mode = "STRICT_TRANS_TABLES,NO_ENGINE_SUBSTITUTION"
 
 # disable sync these schema
 ignore-schemas = "INFORMATION_SCHEMA,PERFORMANCE_SCHEMA,mysql"

drainer/config.go

@@ -45,7 +45,7 @@ var (
 
 // SyncerConfig is the Syncer's configuration.
 type SyncerConfig struct {
-	StrSQLMode       string             `toml:"sql-mode" json:"sql-mode"`
+	StrSQLMode       *string            `toml:"sql-mode" json:"sql-mode"`
 	SQLMode          mysql.SQLMode      `toml:"-" json:"-"`
 	IgnoreSchemas    string             `toml:"ignore-schemas" json:"ignore-schemas"`
 	TxnBatch         int                `toml:"txn-batch" json:"txn-batch"`
@@ -86,9 +86,7 @@ type Config struct {
 func NewConfig() *Config {
 	cfg := &Config{
 		EtcdTimeout: defaultEtcdTimeout,
-		SyncerCfg: &SyncerConfig{
-			StrSQLMode: mysql.DefaultSQLMode,
-		},
+		SyncerCfg:   &SyncerConfig{},
 	}
 	cfg.FlagSet = flag.NewFlagSet("drainer", flag.ContinueOnError)
 	fs := cfg.FlagSet
@@ -164,9 +162,11 @@ func (cfg *Config) Parse(args []string) error {
 		return errors.Trace(err)
 	}
 
-	cfg.SyncerCfg.SQLMode, err = mysql.GetSQLMode(cfg.SyncerCfg.StrSQLMode)
-	if err != nil {
-		return errors.Annotate(err, "invalid config: `sql-mode` must be a valid SQL_MODE")
+	if cfg.SyncerCfg.StrSQLMode != nil {
+		cfg.SyncerCfg.SQLMode, err = mysql.GetSQLMode(*cfg.SyncerCfg.StrSQLMode)
+		if err != nil {
+			return errors.Annotate(err, "invalid config: `sql-mode` must be a valid SQL_MODE")
+		}
 	}
 
 	cfg.tls, err = cfg.Security.ToTLSConfig()

drainer/config_test.go

@@ -31,8 +31,9 @@ func (t *testDrainerSuite) TestConfig(c *C) {
 	c.Assert(cfg.SyncerCfg.TxnBatch, Equals, 1)
 	c.Assert(cfg.SyncerCfg.DestDBType, Equals, "mysql")
 	c.Assert(cfg.SyncerCfg.To.Host, Equals, "127.0.0.1")
-	c.Assert(cfg.SyncerCfg.StrSQLMode, Equals, mysql.DefaultSQLMode)
-	c.Assert(cfg.SyncerCfg.SQLMode, Equals, mysql.ModeStrictTransTables|mysql.ModeNoEngineSubstitution)
+	var strSQLMode *string
+	c.Assert(cfg.SyncerCfg.StrSQLMode, Equals, strSQLMode)
+	c.Assert(cfg.SyncerCfg.SQLMode, Equals, mysql.SQLMode(0))
 }
 
 func (t *testDrainerSuite) TestValidate(c *C) {

drainer/executor/executor.go

@@ -15,7 +15,7 @@ type Executor interface {
 }
 
 // New returns the an Executor instance by given name
-func New(name string, cfg *DBConfig, sqlMode string) (Executor, error) {
+func New(name string, cfg *DBConfig, sqlMode *string) (Executor, error) {
 	switch name {
 	case "mysql", "tidb":
 		return newMysql(cfg, sqlMode)

drainer/executor/mysql.go

@@ -17,7 +17,7 @@ type mysqlExecutor struct {
 	*baseError
 }
 
-func newMysql(cfg *DBConfig, sqlMode string) (Executor, error) {
+func newMysql(cfg *DBConfig, sqlMode *string) (Executor, error) {
 	db, err := pkgsql.OpenDBWithSQLMode("mysql", cfg.Host, cfg.Port, cfg.User, cfg.Password, sqlMode)
 	if err != nil {
 		return nil, errors.Trace(err)

drainer/util.go

@@ -134,7 +134,7 @@ func closeExecutors(executors ...executor.Executor) {
 	}
 }
 
-func createExecutors(destDBType string, cfg *executor.DBConfig, count int, sqlMODE string) ([]executor.Executor, error) {
+func createExecutors(destDBType string, cfg *executor.DBConfig, count int, sqlMODE *string) ([]executor.Executor, error) {
 	executors := make([]executor.Executor, 0, count)
 	for i := 0; i < count; i++ {
 		executor, err := executor.New(destDBType, cfg, sqlMODE)

pkg/sql/sql.go

@@ -118,24 +118,23 @@ func ExecuteTxnWithHistogram(db *sql.DB, sqls []string, args [][]interface{}, hi
 }
 
 // OpenDBWithSQLMode creates an instance of sql.DB.
-func OpenDBWithSQLMode(proto string, host string, port int, username string, password string, sqlMode string) (*sql.DB, error) {
+func OpenDBWithSQLMode(proto string, host string, port int, username string, password string, sqlMode *string) (*sql.DB, error) {
 	dbDSN := fmt.Sprintf("%s:%s@tcp(%s:%d)/?charset=utf8mb4,utf8&multiStatements=true", username, password, host, port)
-	if len(sqlMode) > 0 {
-		log.Info("set sql mode: ", sqlMode)
+	if sqlMode != nil {
 		// same as "set sql_mode = '<sqlMode>'"
-		dbDSN += "&sql_mode='" + url.QueryEscape(sqlMode) + "'"
+		dbDSN += "&sql_mode='" + url.QueryEscape(*sqlMode) + "'"
 	}
 	db, err := sql.Open(proto, dbDSN)
 	if err != nil {
-		return nil, errors.Trace(err)
+		return nil, errors.Annotatef(err, "dsn: %s", dbDSN)
 	}
 
 	return db, nil
 }
 
 // OpenDB creates an instance of sql.DB.
 func OpenDB(proto string, host string, port int, username string, password string) (*sql.DB, error) {
-	return OpenDBWithSQLMode(proto, host, port, username, password, "")
+	return OpenDBWithSQLMode(proto, host, port, username, password, nil)
 }
 
 // IgnoreDDLError checks the error can be ignored or not.