Make GROUP BY work properly for datatypes that only support hashing and not

sorting.  The infrastructure for this was all in place already; it's only
necessary to fix the planner to not assume that sorting is always an available
option.

src/backend/optimizer/plan/planmain.c

@@ -14,7 +14,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planmain.c,v 1.107 2008/07/31 22:47:56 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/planmain.c,v 1.108 2008/08/03 19:10:52 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -288,8 +288,7 @@ query_planner(PlannerInfo *root, List *tlist,
 		 * levels of sort --- and, therefore, certainly need to read all the
 		 * tuples --- unless ORDER BY is a subset of GROUP BY.
 		 */
-		if (root->group_pathkeys && root->sort_pathkeys &&
-			!pathkeys_contained_in(root->sort_pathkeys, root->group_pathkeys))
+		if (!pathkeys_contained_in(root->sort_pathkeys, root->group_pathkeys))
 			tuple_fraction = 0.0;
 	}
 	else if (parse->hasAggs || root->hasHavingQual)

src/backend/parser/parse_clause.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_clause.c,v 1.172 2008/08/02 21:32:00 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_clause.c,v 1.173 2008/08/03 19:10:52 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1351,15 +1351,11 @@ transformGroupClause(ParseState *pstate, List *grouplist,
 		/*
 		 * If no match in ORDER BY, just add it to the result using
 		 * default sort/group semantics.
-		 *
-		 * XXX for now, the planner requires groupClause to be sortable,
-		 * so we have to insist on that here.
 		 */
 		if (!found)
 			result = addTargetToGroupList(pstate, tle,
 										  result, *targetlist,
-										  true,	/* XXX for now */
-										  true);
+										  false, true);
 	}
 
 	return result;