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Clarify what's supposed to happen when a cursor FETCH is rolled back

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by aborting a subtransaction.  Per discussion with Heikki.
This commit is contained in:
Tom Lane 2009-12-02 21:11:12 +00:00
parent 8c1c2e38f6
commit dc588058a0
1 changed files with 8 additions and 5 deletions
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13
doc/src/sgml/ref/rollback_to.sgml
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@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/rollback_to.sgml,v 1.10 2008/11/14 10:22:47 petere Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/rollback_to.sgml,v 1.11 2009/12/02 21:11:12 tgl Exp $
PostgreSQL documentation
-->
@ -77,11 +77,14 @@ ROLLBACK [ WORK | TRANSACTION ] TO [ SAVEPOINT ] <replaceable>savepoint_name</re
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
<command>FETCH</> command inside a savepoint that is later rolled
back, the cursor position remains at the position that <command>FETCH</>
left it pointing to (that is, <command>FETCH</> is not rolled back).
affected by a <command>FETCH</> or <command>MOVE</> command inside a
savepoint that is later rolled back, the cursor remains at the
position that <command>FETCH</> left it pointing to (that is, the cursor
motion caused by <command>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) <emphasis>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
<command>ROLLBACK TO SAVEPOINT</>, the cursor can no longer be used.