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Avoid scribbling on original parsetree during DECLARE CURSOR. This

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prevents problems when the DECLARE is in a portal and is executed
repeatedly, as is possible in v3 protocol.  Per analysis by Oliver
Jowett, though I didn't use his patch exactly.
This commit is contained in:
Tom Lane 2004-11-28 22:16:31 +00:00
parent 3ad9f45c89
commit 839484f9f5
1 changed files with 11 additions and 2 deletions
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13
src/backend/commands/portalcmds.c
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@ -14,7 +14,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/portalcmds.c,v 1.36 2004/09/16 16:58:28 tgl Exp $
* $PostgreSQL: pgsql/src/backend/commands/portalcmds.c,v 1.37 2004/11/28 22:16:31 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -61,13 +61,22 @@ PerformCursorOpen(DeclareCursorStmt *stmt, ParamListInfo params)
if (!(stmt->options & CURSOR_OPT_HOLD))
RequireTransactionChain((void *) stmt, "DECLARE CURSOR");
/*
* Because the planner is not cool about not scribbling on its input,
* we make a preliminary copy of the source querytree. This prevents
* problems in the case that the DECLARE CURSOR is in a portal and is
* executed repeatedly. XXX the planner really shouldn't modify its
* input ... FIXME someday.
*/
query = copyObject(stmt->query);
/*
* The query has been through parse analysis, but not rewriting or
* planning as yet. Note that the grammar ensured we have a SELECT
* query, so we are not expecting rule rewriting to do anything
* strange.
*/
rewritten = QueryRewrite((Query *) stmt->query);
rewritten = QueryRewrite(query);
if (list_length(rewritten) != 1 || !IsA(linitial(rewritten), Query))
elog(ERROR, "unexpected rewrite result");
query = (Query *) linitial(rewritten);