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.

1 files changed, 16 insertions, 24 deletions

diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 98385dd96f6..588528daa1d 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.72 1999/08/16 02:17:43 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.73 1999/08/21 03:48:58 tgl Exp $
  *
  * NOTES
  *	  Most of the read functions for plan nodes are tested. (In fact, they
@@ -184,12 +184,13 @@ _readSortClause()
 
 	local_node = makeNode(SortClause);
 
-	token = lsptok(NULL, &length);		/* skip the :resdom */
-	local_node->resdom = nodeRead(true);
+	token = lsptok(NULL, &length);		/* skip :tleSortGroupRef */
+	token = lsptok(NULL, &length);		/* get tleSortGroupRef */
+	local_node->tleSortGroupRef = strtoul(token, NULL, 10);
 
-	token = lsptok(NULL, &length);		/* skip :opoid */
-	token = lsptok(NULL, &length);		/* get opoid */
-	local_node->opoid = strtoul(token, NULL, 10);
+	token = lsptok(NULL, &length);		/* skip :sortop */
+	token = lsptok(NULL, &length);		/* get sortop */
+	local_node->sortop = strtoul(token, NULL, 10);
 
 	return local_node;
 }
@@ -207,13 +208,13 @@ _readGroupClause()
 
 	local_node = makeNode(GroupClause);
 
-	token = lsptok(NULL, &length);		/* skip :grpOpoid */
-	token = lsptok(NULL, &length);		/* get grpOpoid */
-	local_node->grpOpoid = strtoul(token, NULL, 10);
+	token = lsptok(NULL, &length);		/* skip :tleSortGroupRef */
+	token = lsptok(NULL, &length);		/* get tleSortGroupRef */
+	local_node->tleSortGroupRef = strtoul(token, NULL, 10);
 
-	token = lsptok(NULL, &length);		/* skip :tleGroupref */
-	token = lsptok(NULL, &length);		/* get tleGroupref */
-	local_node->tleGroupref = strtoul(token, NULL, 10);
+	token = lsptok(NULL, &length);		/* skip :sortop */
+	token = lsptok(NULL, &length);		/* get sortop */
+	local_node->sortop = strtoul(token, NULL, 10);
 
 	return local_node;
 }
@@ -600,15 +601,10 @@ static Agg *
 _readAgg()
 {
 	Agg		   *local_node;
-	char	   *token;
-	int			length;
 
 	local_node = makeNode(Agg);
 	_getPlan((Plan *) local_node);
 
-	token = lsptok(NULL, &length);		/* eat :agg */
-	local_node->aggs = nodeRead(true);	/* now read it */
-
 	return local_node;
 }
 
@@ -712,9 +708,9 @@ _readResdom()
 	token = lsptok(NULL, &length);		/* get reskeyop */
 	local_node->reskeyop = (Oid) atol(token);
 
-	token = lsptok(NULL, &length);		/* eat :resgroupref */
-	token = lsptok(NULL, &length);		/* get resgroupref */
-	local_node->resgroupref = strtoul(token, NULL, 10);
+	token = lsptok(NULL, &length);		/* eat :ressortgroupref */
+	token = lsptok(NULL, &length);		/* get ressortgroupref */
+	local_node->ressortgroupref = strtoul(token, NULL, 10);
 
 	token = lsptok(NULL, &length);		/* eat :resjunk */
 	token = lsptok(NULL, &length);		/* get resjunk */
@@ -1163,10 +1159,6 @@ _readAggref()
 	token = lsptok(NULL, &length);		/* eat :target */
 	local_node->target = nodeRead(true);		/* now read it */
 
-	token = lsptok(NULL, &length);		/* eat :aggno */
-	token = lsptok(NULL, &length);		/* get aggno */
-	local_node->aggno = atoi(token);
-
 	token = lsptok(NULL, &length);		/* eat :usenulls */
 	token = lsptok(NULL, &length);		/* get usenulls */
 	local_node->usenulls = (token[0] == 't') ? true : false;