|The PostgreSQL 9.0 Reference Manual - Volume 1B - SQL Command Reference
by The PostgreSQL Global Development Group
Paperback (6"x9"), 488 pages
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1.126 ROLLBACK TO SAVEPOINT
ROLLBACK TO SAVEPOINT -- roll back to a savepoint
ROLLBACK [ WORK | TRANSACTION ] TO [ SAVEPOINT ] savepoint_name
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.
- The savepoint to roll back to.
RELEASE SAVEPOINT to destroy a savepoint without
discarding the effects of commands executed after it was established.
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
MOVE command inside a
savepoint that is later rolled back, the cursor remains at the
FETCH left it pointing to (that is, the cursor
motion caused by
FETCH is not rolled back).
Closing a cursor is not undone by rolling back, either.
However, other side-effects caused by the cursor's query (such as
side-effects of volatile functions called by the query) are
rolled back if they occur during a savepoint that is later rolled back.
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.
To undo the effects of the commands executed after
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;
The SQL standard specifies that the key word
SAVEPOINT is mandatory, but PostgreSQL
and Oracle allow it to be omitted. SQL allows
TRANSACTION, as a noise word
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.
|ISBN 9781906966058||The PostgreSQL 9.0 Reference Manual - Volume 1B - SQL Command Reference||See the print edition|