/usr/man2/cat.l/savepoint.l.Z

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 com-
       mands that are executed after it was established  to  be  rolled  back,
       restoring the transaction state to what it was at the time of the save-
       point.

PARAMETERS

       savepoint_name
              The name to give to the new savepoint.

NOTES

       Use ROLLBACK TO SAVEPOINT [rollback_to_savepoint(l)] to rollback  to  a
       savepoint.  Use  RELEASE  SAVEPOINT [release_savepoint(l)] to destroy a
       savepoint, keeping the effects of commands executed after it was estab-
       lished.

       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.

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  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 [begin(l)], COMMIT [commit(l)], RELEASE SAVEPOINT  [release_save-
       point(l)],   ROLLBACK   [rollback(l)],  ROLLBACK  TO  SAVEPOINT  [roll-
       back_to_savepoint(l)]

SQL - Language Statements         2005-11-05                       SAVEPOINT()