savepoint(7) [linux man page]

SAVEPOINT(7)                                                       SQL Commands                                                       SAVEPOINT(7)

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.

NOTES

       Use ROLLBACK TO SAVEPOINT [rollback_to_savepoint(7)] to rollback to a savepoint. Use RELEASE SAVEPOINT [release_savepoint(7)] 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.

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(7)],  COMMIT  [commit(7)],  RELEASE  SAVEPOINT  [release_savepoint(7)],  ROLLBACK [rollback(7)], ROLLBACK TO SAVEPOINT [roll-
       back_to_savepoint(7)]

SQL - Language Statements                                           2010-05-14                                                        SAVEPOINT(7)

ROLLBACK TO 
SAVEPOINT(7)					   SQL Commands 					  ROLLBACK TO SAVEPOINT(7)

NAME

       ROLLBACK TO SAVEPOINT - roll back to a savepoint

SYNOPSIS

       ROLLBACK [ WORK | TRANSACTION ] TO [ SAVEPOINT ] savepoint_name

DESCRIPTION

       Roll  back all commands that were executed after the savepoint was established. The savepoint remains valid and can be rolled back to again
       later, if needed.

       ROLLBACK TO SAVEPOINT implicitly destroys all savepoints that were established after the named savepoint.

PARAMETERS

       savepoint_name
	      The savepoint to roll back to.

NOTES

       Use RELEASE SAVEPOINT [release_savepoint(7)] to destroy a savepoint without discarding the effects of commands executed after it was estab-
       lished.

       Specifying a savepoint name that has not been established is an error.

       Cursors	have  somewhat	non-transactional behavior with respect to savepoints. Any cursor that is opened inside a savepoint will be closed
       when the savepoint is rolled back. If a previously opened cursor is affected by a FETCH command inside a savepoint  that  is  later  rolled
       back,  the cursor position remains at the position that FETCH left it pointing to (that is, FETCH is not rolled back).  Closing a cursor is
       not undone by rolling back, either.  A cursor whose execution causes a transaction to abort is put in a cannot-execute state, so while  the
       transaction can be restored using ROLLBACK TO SAVEPOINT, the cursor can no longer be used.

EXAMPLES

       To undo the effects of the commands executed after my_savepoint was established:

       ROLLBACK TO SAVEPOINT my_savepoint;

       Cursor positions are not affected by savepoint rollback:

       BEGIN;

       DECLARE foo CURSOR FOR SELECT 1 UNION SELECT 2;

       SAVEPOINT foo;

       FETCH 1 FROM foo;
	?column?
       ----------
	       1

       ROLLBACK TO SAVEPOINT foo;

       FETCH 1 FROM foo;
	?column?
       ----------
	       2

       COMMIT;

COMPATIBILITY

       The  SQL  standard  specifies  that  the key word SAVEPOINT is mandatory, but PostgreSQL and Oracle allow it to be omitted. SQL allows only
       WORK, not TRANSACTION, as a noise word after ROLLBACK. Also, SQL has an optional clause AND [ NO ] CHAIN which is not  currently  supported
       by PostgreSQL. Otherwise, this command conforms to the SQL standard.

SEE ALSO

       BEGIN [begin(7)], COMMIT [commit(7)], RELEASE SAVEPOINT [release_savepoint(7)], ROLLBACK [rollback(7)], SAVEPOINT [savepoint(7)]

SQL - Language Statements					    2010-05-14						  ROLLBACK TO SAVEPOINT(7)