ROLLBACK TO SAVEPOINT
Rolls back the current transaction to a savepoint.
ROLLBACK [WORK | TRANSACTION] TO [SAVEPOINT] <savepoint_name>
This command will 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.
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
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 can’t-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
my_savepoint was established:
ROLLBACK TO SAVEPOINT my_savepoint;
Cursor positions are not affected by a 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
The SQL standard specifies that the key word
SAVEPOINT is mandatory, but HAWQ (and Oracle) allow it to be omitted. SQL allows only
TRANSACTION, as a stopword after
ROLLBACK. Also, SQL has an optional clause
AND [NO] CHAIN which is not currently supported by HAWQ. Otherwise, this command conforms to the SQL standard.