From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sun, 28 Nov 2004 22:16:49 +0000 (+0000)
Subject: Avoid scribbling on original parsetree during DECLARE CURSOR.  This
X-Git-Tag: REL7_4_7~26
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=0b9f48daf2601a1be20f8a85ad151bdc05dd1907;p=postgresql

Avoid scribbling on original parsetree during DECLARE CURSOR.  This
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.
---

diff --git a/src/backend/commands/portalcmds.c b/src/backend/commands/portalcmds.c
index 27cd7503c3..8c4c9fe282 100644
--- a/src/backend/commands/portalcmds.c
+++ b/src/backend/commands/portalcmds.c
@@ -14,7 +14,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/portalcmds.c,v 1.24 2003/08/24 21:02:43 petere Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/portalcmds.c,v 1.24.2.1 2004/11/28 22:16:49 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -61,13 +61,22 @@ PerformCursorOpen(DeclareCursorStmt *stmt)
 	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 (length(rewritten) != 1 || !IsA(lfirst(rewritten), Query))
 		elog(ERROR, "unexpected rewrite result");
 	query = (Query *) lfirst(rewritten);