From 31a0f1d33bccd69c76980d9cc602ad75ae696161 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Wed, 28 Jan 2004 07:46:44 +0000
Subject: [PATCH] Fix oversight in check_ungrouped_columns optimization that
avoids unnecessary checks for complex grouping expressions: we cannot check
whether the expressions are simple Vars until after we apply
flatten_join_alias_vars, because in the case of FULL JOIN that routine can
introduce non-Var expressions. Per example from Joel Knight.
---
src/backend/parser/parse_agg.c | 25 ++++++++++++++++++-------
1 file changed, 18 insertions(+), 7 deletions(-)
diff --git a/src/backend/parser/parse_agg.c b/src/backend/parser/parse_agg.c
index ab365ac84dd..6f85595610d 100644
--- a/src/backend/parser/parse_agg.c
+++ b/src/backend/parser/parse_agg.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/parser/parse_agg.c,v 1.60 2003/11/29 19:51:51 pgsql Exp $
+ * $PostgreSQL: pgsql/src/backend/parser/parse_agg.c,v 1.61 2004/01/28 07:46:44 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -98,7 +98,7 @@ void
parseCheckAggregates(ParseState *pstate, Query *qry)
{
List *groupClauses = NIL;
- bool have_non_var_grouping = false;
+ bool have_non_var_grouping;
List *lst;
bool hasJoinRTEs;
Node *clause;
@@ -127,9 +127,7 @@ parseCheckAggregates(ParseState *pstate, Query *qry)
* No aggregates allowed in GROUP BY clauses, either.
*
* While we are at it, build a list of the acceptable GROUP BY
- * expressions for use by check_ungrouped_columns() (this avoids
- * repeated scans of the targetlist within the recursive routine...).
- * And detect whether any of the expressions aren't simple Vars.
+ * expressions for use by check_ungrouped_columns().
*/
foreach(lst, qry->groupClause)
{
@@ -144,8 +142,6 @@ parseCheckAggregates(ParseState *pstate, Query *qry)
(errcode(ERRCODE_GROUPING_ERROR),
errmsg("aggregates not allowed in GROUP BY clause")));
groupClauses = lcons(expr, groupClauses);
- if (!IsA(expr, Var))
- have_non_var_grouping = true;
}
/*
@@ -170,6 +166,21 @@ parseCheckAggregates(ParseState *pstate, Query *qry)
groupClauses = (List *) flatten_join_alias_vars(qry,
(Node *) groupClauses);
+ /*
+ * Detect whether any of the grouping expressions aren't simple Vars;
+ * if they're all Vars then we don't have to work so hard in the
+ * recursive scans. (Note we have to flatten aliases before this.)
+ */
+ have_non_var_grouping = false;
+ foreach(lst, groupClauses)
+ {
+ if (!IsA((Node *) lfirst(lst), Var))
+ {
+ have_non_var_grouping = true;
+ break;
+ }
+ }
+
/*
* Check the targetlist and HAVING clause for ungrouped variables.
*/
--
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