From 1f5ca045a435bc6aa9c98d7296973925c5208add Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Wed, 21 Jun 2006 18:30:11 +0000
Subject: [PATCH] Disallow aggregate functions in UPDATE commands (unless
within a sub-SELECT). This is disallowed by the SQL spec because it doesn't
have any very sensible interpretation. Historically Postgres has allowed it
but behaved strangely. As of PG 8.1 a server crash is possible if the MIN/MAX
index optimization gets applied; rather than try to "fix" that, it seems best
to just enforce the spec restriction. Per report from Josh Drake and Alvaro
Herrera.
---
src/backend/parser/analyze.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index 566c9a0488d..4e30d2b96f3 100644
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -6,7 +6,7 @@
* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/backend/parser/analyze.c,v 1.334 2006/04/30 18:30:39 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/parser/analyze.c,v 1.335 2006/06/21 18:30:11 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -1613,7 +1613,7 @@ transformRuleStmt(ParseState *pstate, RuleStmt *stmt,
if (pstate->p_hasAggs)
ereport(ERROR,
(errcode(ERRCODE_GROUPING_ERROR),
- errmsg("rule WHERE condition may not contain aggregate functions")));
+ errmsg("cannot use aggregate function in rule WHERE condition")));
/* save info about sublinks in where clause */
qry->hasSubLinks = pstate->p_hasSubLinks;
@@ -2346,9 +2346,16 @@ transformUpdateStmt(ParseState *pstate, UpdateStmt *stmt)
qry->jointree = makeFromExpr(pstate->p_joinlist, qual);
qry->hasSubLinks = pstate->p_hasSubLinks;
- qry->hasAggs = pstate->p_hasAggs;
+
+ /*
+ * Top-level aggregates are simply disallowed in UPDATE, per spec.
+ * (From an implementation point of view, this is forced because the
+ * implicit ctid reference would otherwise be an ungrouped variable.)
+ */
if (pstate->p_hasAggs)
- parseCheckAggregates(pstate, qry);
+ ereport(ERROR,
+ (errcode(ERRCODE_GROUPING_ERROR),
+ errmsg("cannot use aggregate function in UPDATE")));
/*
* Now we are done with SELECT-like processing, and can get on with
--
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