From db436adf761bd5cb7990745ceba2959ac4bfca7c Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sat, 21 Aug 1999 03:49:17 +0000
Subject: Major revision of sort-node handling: push knowledge of query sort
 order down into planner, instead of handling it only at the very top level of
 the planner.  This fixes many things.  An explicit sort is now avoided if
 there is a cheaper alternative (typically an indexscan) not only for ORDER
 BY, but also for the internal sort of GROUP BY.  It works even when there is
 no other reason (such as a WHERE condition) to consider the indexscan.  It
 works for indexes on functions.  It works for indexes on functions,
 backwards.  It's just so cool...

CAUTION: I have changed the representation of SortClause nodes, therefore
THIS UPDATE BREAKS STORED RULES.  You will need to initdb.
---
 src/backend/utils/adt/ruleutils.c | 23 ++++++-----------------
 1 file changed, 6 insertions(+), 17 deletions(-)

(limited to 'src/backend/utils/adt/ruleutils.c')

diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 8f365f2efbe..008402e26f3 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -3,7 +3,7 @@
  *			  out of it's tuple
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/ruleutils.c,v 1.21 1999/07/17 20:17:59 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/ruleutils.c,v 1.22 1999/08/21 03:48:53 tgl Exp $
  *
  *	  This software is copyrighted by Jan Wieck - Hamburg.
  *
@@ -41,6 +41,7 @@
 #include "postgres.h"
 #include "executor/spi.h"
 #include "optimizer/clauses.h"
+#include "optimizer/tlist.h"
 #include "utils/lsyscache.h"
 #include "catalog/pg_shadow.h"
 #include "catalog/pg_index.h"
@@ -1248,23 +1249,11 @@ get_rule_expr(QryHier *qh, int rt_index, Node *node, bool varprefix)
 		case T_GroupClause:
 			{
 				GroupClause *grp = (GroupClause *) node;
-				List	   *l;
-				TargetEntry *tle = NULL;
-
-				foreach(l, qh->query->targetList)
-				{
-					if (((TargetEntry *) lfirst(l))->resdom->resgroupref ==
-						grp->tleGroupref)
-					{
-						tle = (TargetEntry *) lfirst(l);
-						break;
-					}
-				}
-
-				if (tle == NULL)
-					elog(ERROR, "GROUP BY expression not found in targetlist");
+				Node *groupexpr;
 
-				return get_rule_expr(qh, rt_index, (Node *) tle, varprefix);
+				groupexpr = get_sortgroupclause_expr(grp,
+													 qh->query->targetList);
+				return get_rule_expr(qh, rt_index, groupexpr, varprefix);
 			}
 			break;
 
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