meta/mysql: set defalut transation_isolation to repeatable-read (#5432)

pkg/meta/sql.go

@@ -266,6 +266,8 @@ func recoveryMysqlPwd(addr string) string {
 	return addr
 }
 
+var setTransationIsolation func(dns string) (string, error)
+
 func newSQLMeta(driver, addr string, conf *Config) (Meta, error) {
 	var searchPath string
 	if driver == "postgres" {
@@ -285,8 +287,12 @@ func newSQLMeta(driver, addr string, conf *Config) (Meta, error) {
 	}
 
 	// escaping is not necessary for mysql password https://github.com/go-sql-driver/mysql#password
-	if driver == "mysql" {
+	if driver == "mysql" && setTransationIsolation != nil {
 		addr = recoveryMysqlPwd(addr)
+		var err error
+		if addr, err = setTransationIsolation(addr); err != nil {
+			return nil, err
+		}
 	}
 
 	if driver == "sqlite3" {

pkg/meta/sql_mysql.go

@@ -30,7 +30,20 @@ func isMySQLDuplicateEntryErr(err error) bool {
 	return false
 }
 
+func setMySQLTransationIsolation(dns string) (string, error) {
+	cfg, err := mysql.ParseDSN(dns)
+	if err != nil {
+		return "", err
+	}
+	if cfg.Params == nil {
+		cfg.Params = make(map[string]string)
+	}
+	cfg.Params["transaction_isolation"] = "'repeatable-read'"
+	return cfg.FormatDSN(), nil
+}
+
 func init() {
 	dupErrorCheckers = append(dupErrorCheckers, isMySQLDuplicateEntryErr)
+	setTransationIsolation = setMySQLTransationIsolation
 	Register("mysql", newSQLMeta)
 }