PolarDB:SAVEPOINT

Description

A savepoint is a special mark inside a transaction that allows all commands that are executed after it was established to be rolled back, restoring the transaction state to what it was at the time of the savepoint.

Synopsis

    SAVEPOINT savepoint_name

Parameters

savepoint_name: The name to give to the new savepoint. If savepoints with the same name already exist, they will be inaccessible until newer identically-named savepoints are released.

Notes

• Use ROLLBACK to rollback to a savepoint. Use RELEASE SAVEPOINT to destroy a savepoint, keeping the effects of commands executed after it was established.

• Savepoints can only be established when inside a transaction block. There can be multiple savepoints defined within a transaction.

Examples

To establish a savepoint and later undo the effects of all commands executed after it was established:

    BEGIN;
        INSERT INTO table1 VALUES (1);
        SAVEPOINT my_savepoint;
        INSERT INTO table1 VALUES (2);
        ROLLBACK TO SAVEPOINT my_savepoint;
        INSERT INTO table1 VALUES (3);
    COMMIT;

The above transaction will insert the values 1 and 3, but not 2.

To establish and later destroy a savepoint:

    BEGIN;
        INSERT INTO table1 VALUES (3);
        SAVEPOINT my_savepoint;
        INSERT INTO table1 VALUES (4);
        RELEASE SAVEPOINT my_savepoint;
    COMMIT;

The above transaction will insert both 3 and 4.