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SAVEPOINT

SAVEPOINT is a feature introduced in TiDB v6.2.0. The syntax is as follows:

SAVEPOINT identifier
ROLLBACK TO [SAVEPOINT] identifier
RELEASE SAVEPOINT identifier
  • SAVEPOINT is used to set a savepoint of a specified name in the current transaction. If a savepoint with the same name already exists, it will be deleted and a new savepoint with the same name will be set.

  • ROLLBACK TO SAVEPOINT rolls back a transaction to the savepoint of a specified name and does not terminate the transaction. Data changes made to the table data after the savepoint will be reverted in the rollback, and all savepoints after the savepoint are deleted. In a pessimistic transaction, the locks held by the transaction are not rolled back. Instead, the locks will be released when the transaction ends.

    If the savepoint specified in the ROLLBACK TO SAVEPOINT statement does not exist, the statement returns the following error:

    ERROR 1305 (42000): SAVEPOINT identifier does not exist
    
  • RELEASE SAVEPOINT statement removes the named savepoint and all savepoints after this savepoint from the current transaction, without committing or rolling back the current transaction. If the savepoint of the specified name does not exist, the following error is returned:

    ERROR 1305 (42000): SAVEPOINT identifier does not exist
    

    After the transaction is committed or rolled back, all savepoints in the transaction will be deleted.

Examples

Create a table t1:

CREATE TABLE t1 (a INT NOT NULL PRIMARY KEY);
Query OK, 0 rows affected (0.12 sec)

Start the current transaction:

BEGIN;
Query OK, 0 rows affected (0.00 sec)

Insert data into the table and set a savepoint sp1:

INSERT INTO t1 VALUES (1);
Query OK, 1 row affected (0.00 sec)
SAVEPOINT sp1;
Query OK, 0 rows affected (0.01 sec)

Insert data into the table again and set a savepoint sp2:

INSERT INTO t1 VALUES (2);
Query OK, 1 row affected (0.00 sec)
SAVEPOINT sp2;
Query OK, 0 rows affected (0.01 sec)

Release the savepoint sp2:

RELEASE SAVEPOINT sp2;
Query OK, 0 rows affected (0.01 sec)

Roll back to the savepoint sp1:

ROLLBACK TO SAVEPOINT sp1;
Query OK, 0 rows affected (0.01 sec)

Commit the transaction and query the table. Only the data inserted before sp1 is returned.

COMMIT;
Query OK, 0 rows affected (0.01 sec)
SELECT * FROM t1;
+---+
| a |
+---+
| 1 |
+---+
1 row in set

MySQL compatibility

When ROLLBACK TO SAVEPOINT is used to roll back a transaction to a specified savepoint, MySQL releases the locks held only after the specified savepoint, while in TiDB pessimistic transaction, TiDB does not immediately release the locks held after the specified savepoint. Instead, TiDB releases all locks when the transaction is committed or rolled back.

See also

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