Creates a special mark, called a savepoint, inside a transaction. A savepoint allows all commands that are executed after it was established to be rolled back, restoring the transaction to the state it was in at the point in which the savepoint was established.
Savepoints are useful when creating nested transactions. For example, a savepoint could be created at the beginning of a subroutine. That way, the result of the subroutine could be rolled back if necessary.
Specifies the name of the savepoint to create.
- Savepoints are local to a transaction and can only be established when inside a transaction block.
- Multiple savepoints can be defined within a transaction.
- If a savepoint with the same name already exists, it is replaced with the new savepoint.
The following example illustrates how a savepoint determines which values within a transaction can be rolled back. The values 102 and 103 that were entered after the savepoint,
my_savepoint, was established are rolled back. Only the values 101 and 104 are inserted at commit.
=> INSERT INTO T1 (product_key) VALUES (101); => SAVEPOINT my_savepoint; => INSERT INTO T1 (product_key) VALUES (102); => INSERT INTO T1 (product_key) VALUES (103); => ROLLBACK TO SAVEPOINT my_savepoint; => INSERT INTO T1 (product_key) VALUES (104); => COMMIT; => SELECT product_key FROM T1; . . . 101 104 (2 rows)