NAME

       SAVEPOINT - define a new savepoint within the current transaction

SYNOPSIS

       SAVEPOINT savepoint_name

DESCRIPTION

       SAVEPOINT establishes a new savepoint within the current transaction.

       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.

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 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.

       To use a single savepoint name:

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

               -- rollback to the second savepoint
               ROLLBACK TO SAVEPOINT my_savepoint;
               SELECT * FROM table1;               -- shows rows 1 and 2

               -- release the second savepoint
               RELEASE SAVEPOINT my_savepoint;

               -- rollback to the first savepoint
               ROLLBACK TO SAVEPOINT my_savepoint;
               SELECT * FROM table1;               -- shows only row 1
           COMMIT;

       The above transaction shows row 3 being rolled back first, then row 2.

COMPATIBILITY

       SQL requires a savepoint to be destroyed automatically when another savepoint with the
       same name is established. In PostgreSQL, the old savepoint is kept, though only the more
       recent one will be used when rolling back or releasing. (Releasing the newer savepoint
       with RELEASE SAVEPOINT will cause the older one to again become accessible to ROLLBACK TO
       SAVEPOINT and RELEASE SAVEPOINT.) Otherwise, SAVEPOINT is fully SQL conforming.

SEE ALSO

       BEGIN(7), COMMIT(7), RELEASE SAVEPOINT (RELEASE_SAVEPOINT(7)), ROLLBACK(7), ROLLBACK TO
       SAVEPOINT (ROLLBACK_TO_SAVEPOINT(7))