Redesign DISTINCT ON as discussed in pgsql-sql 1/25/00: syntax is now

SELECT DISTINCT ON (expr [, expr ...]) targetlist ...
and there is a check to make sure that the user didn't specify an ORDER BY
that's incompatible with the DISTINCT operation.
Reimplement nodeUnique and nodeGroup to use the proper datatype-specific
equality function for each column being compared --- they used to do
bitwise comparisons or convert the data to text strings and strcmp().
(To add insult to injury, they'd look up the conversion functions once
for each tuple...)  Parse/plan representation of DISTINCT is now a list
of SortClause nodes.
initdb forced by querytree change...

1 files changed, 24 insertions, 9 deletions

diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index ab69742482a..70a73821641 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.81 2000/01/26 05:56:37 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.82 2000/01/27 18:11:30 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1342,16 +1342,19 @@ make_group(List *tlist,
 }
 
 /*
- * The uniqueAttr argument must be a null-terminated string,
- * either the name of the attribute to select unique on
- * or "*"
+ * distinctList is a list of SortClauses, identifying the targetlist items
+ * that should be considered by the Unique filter.
  */
 
 Unique *
-make_unique(List *tlist, Plan *lefttree, char *uniqueAttr)
+make_unique(List *tlist, Plan *lefttree, List *distinctList)
 {
 	Unique	   *node = makeNode(Unique);
 	Plan	   *plan = &node->plan;
+	int			numCols = length(distinctList);
+	int			keyno = 0;
+	AttrNumber *uniqColIdx;
+	List	   *slitem;
 
 	copy_plan_costsize(plan, lefttree);
 	plan->state = (EState *) NULL;
@@ -1361,10 +1364,22 @@ make_unique(List *tlist, Plan *lefttree, char *uniqueAttr)
 	plan->righttree = NULL;
 	node->nonameid = _NONAME_RELATION_ID_;
 	node->keycount = 0;
-	if (strcmp(uniqueAttr, "*") == 0)
-		node->uniqueAttr = NULL;
-	else
-		node->uniqueAttr = pstrdup(uniqueAttr);
+
+	/* convert SortClause list into array of attr indexes, as wanted by exec */
+	Assert(numCols > 0);
+	uniqColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
+
+	foreach(slitem, distinctList)
+	{
+		SortClause	   *sortcl = (SortClause *) lfirst(slitem);
+		TargetEntry	   *tle = get_sortgroupclause_tle(sortcl, tlist);
+
+		uniqColIdx[keyno++] = tle->resdom->resno;
+	}
+
+	node->numCols = numCols;
+	node->uniqColIdx = uniqColIdx;
+
 	return node;
 }