From a3d2a94303d74cebaae2f55834f1d03ff39a423e Mon Sep 17 00:00:00 2001
From: blylei <blylei.info@gmail.com>
Date: Wed, 17 Apr 2024 22:43:26 +0800
Subject: [PATCH] via a pre-connection detect real transaction-isolation
 variable name

---
 go/mysql/connection.go |  4 +++-
 go/mysql/utils.go      | 21 +++++++++++++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/go/mysql/connection.go b/go/mysql/connection.go
index 7db51afe4..f125492b4 100644
--- a/go/mysql/connection.go
+++ b/go/mysql/connection.go
@@ -136,7 +136,6 @@ func (this *ConnectionConfig) GetDBUri(databaseName string) string {
 		"interpolateParams=true",
 		fmt.Sprintf("charset=%s", this.Charset),
 		fmt.Sprintf("tls=%s", tlsOption),
-		fmt.Sprintf("transaction_isolation=%q", this.TransactionIsolation),
 		fmt.Sprintf("timeout=%fs", this.Timeout),
 		fmt.Sprintf("readTimeout=%fs", this.Timeout),
 		fmt.Sprintf("writeTimeout=%fs", this.Timeout),
@@ -144,6 +143,9 @@ func (this *ConnectionConfig) GetDBUri(databaseName string) string {
 	if this.WaitTimeout > 0 {
 		connectionParams = append(connectionParams, fmt.Sprintf("wait_timeout=%fs", this.WaitTimeout))
 	}
+	tmpDsn := fmt.Sprintf("%s:%s@tcp(%s:%d)/mysql?", this.User, this.Password, hostname, this.Key.Port)
+	TrxName := GetTrxVariableName(tmpDsn)
+	connectionParams = append(connectionParams, fmt.Sprintf("%s=%q", TrxName, this.TransactionIsolation))
 
 	return fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?%s", this.User, this.Password, hostname, this.Key.Port, databaseName, strings.Join(connectionParams, "&"))
 }
diff --git a/go/mysql/utils.go b/go/mysql/utils.go
index c69a3f255..e6db3b531 100644
--- a/go/mysql/utils.go
+++ b/go/mysql/utils.go
@@ -175,6 +175,27 @@ func GetInstanceKey(db *gosql.DB) (instanceKey *InstanceKey, err error) {
 	return instanceKey, err
 }
 
+// GetTrxVariableName get real transaction_isolation via a pre-connection, transaction_isolation or tx_isolation
+func GetTrxVariableName(dsn string) string {
+	var trxVariableName string
+	const (
+		transactionIsolation string = "transaction_isolation"
+		txIsolation          string = "tx_isolation"
+	)
+	query := fmt.Sprintf("select @@%s;", txIsolation)
+	db, err := gosql.Open("mysql", dsn)
+	defer func() {
+		db.Close()
+	}()
+	if err != nil {
+		return ""
+	}
+	if err := db.QueryRow(query).Scan(&trxVariableName); err == nil {
+		return txIsolation
+	}
+	return transactionIsolation
+}
+
 // GetTableColumns reads column list from given table
 func GetTableColumns(db *gosql.DB, databaseName, tableName string) (*sql.ColumnList, *sql.ColumnList, error) {
 	query := fmt.Sprintf(`