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, 7 deletions

diff --git a/src/backend/optimizer/util/tlist.c b/src/backend/optimizer/util/tlist.c
index 8edf44190a4..b4c745b25f3 100644
--- a/src/backend/optimizer/util/tlist.c
+++ b/src/backend/optimizer/util/tlist.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/tlist.c,v 1.42 2000/01/26 05:56:40 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/util/tlist.c,v 1.43 2000/01/27 18:11:34 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -217,15 +217,16 @@ get_expr(TargetEntry *tle)
 }
 
 /*
- * get_sortgroupclause_expr
+ * get_sortgroupclause_tle
  *		Find the targetlist entry matching the given SortClause
- *		(or GroupClause) by ressortgroupref, and return its expression.
+ *		(or GroupClause) by ressortgroupref, and return it.
  *
  * Because GroupClause is typedef'd as SortClause, either kind of
  * node can be passed without casting.
  */
-Node *
-get_sortgroupclause_expr(SortClause *sortClause, List *targetList)
+TargetEntry *
+get_sortgroupclause_tle(SortClause *sortClause,
+						List *targetList)
 {
 	Index		refnumber = sortClause->tleSortGroupRef;
 	List	   *l;
@@ -235,9 +236,25 @@ get_sortgroupclause_expr(SortClause *sortClause, List *targetList)
 		TargetEntry *tle = (TargetEntry *) lfirst(l);
 
 		if (tle->resdom->ressortgroupref == refnumber)
-			return tle->expr;
+			return tle;
 	}
 
-	elog(ERROR, "get_sortgroupclause_expr: ORDER/GROUP BY expression not found in targetlist");
+	elog(ERROR, "get_sortgroupclause_tle: ORDER/GROUP BY expression not found in targetlist");
 	return NULL;				/* keep compiler quiet */
 }
+
+/*
+ * get_sortgroupclause_expr
+ *		Find the targetlist entry matching the given SortClause
+ *		(or GroupClause) by ressortgroupref, and return its expression.
+ *
+ * Because GroupClause is typedef'd as SortClause, either kind of
+ * node can be passed without casting.
+ */
+Node *
+get_sortgroupclause_expr(SortClause *sortClause, List *targetList)
+{
+	TargetEntry *tle = get_sortgroupclause_tle(sortClause, targetList);
+
+	return tle->expr;
+}