Bug #119405 Set @@transaction_isolation does not take effect.

Submitted:	17 Nov 2025 3:12
Reporter:	Sakurajima Mai	Email Updates:
Status:	Open	Impact on me:	None
Category:	MySQL Server: Locking	Severity:	S3 (Non-critical)
Version:	8.0.41	OS:	Any
Assigned to:		CPU Architecture:	Any

Description:
mysql> SELECT @@transaction_isolation;
+-------------------------+
| @@transaction_isolation |
+-------------------------+
| READ-COMMITTED          |
+-------------------------+
1 row in set (0.00 sec)

mysql> set @@transaction_isolation = "SERIALIZABLE";
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT @@transaction_isolation;
+-------------------------+
| @@transaction_isolation |
+-------------------------+
| READ-COMMITTED          |
+-------------------------+
1 row in set (0.00 sec)

How to repeat:
SELECT @@transaction_isolation;

set @@transaction_isolation = "SERIALIZABLE";

SELECT @@transaction_isolation;

Suggested fix:
mysql> set @@transaction_isolation = "SERIALIZABLE";
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT @@transaction_isolation;
+-------------------------+
| @@transaction_isolation |
+-------------------------+
| SERIALIZABLE            |
+-------------------------+
1 row in set (0.00 sec)

Page generated in 0.037 sec. using MySQL 8.4.7-u6-cloud

Timestamp references displayed by the system are UTC.
Content reproduced on this site is the property of the respective copyright holders.
It is not reviewed in advance by Oracle and does not necessarily represent the opinion of Oracle or any other party.