Teach the system how to use hashing for UNION. (INTERSECT/EXCEPT will follow,

but seem like a separate patch since most of the remaining work is on the
executor side.)  I took the opportunity to push selection of the grouping
operators for set operations into the parser where it belongs.  Otherwise this
is just a small exercise in making prepunion.c consider both alternatives.

As with the recent DISTINCT patch, this means we can UNION on datatypes that
can hash but not sort, and it means that UNION without ORDER BY is no longer
certain to produce sorted output.

1 files changed, 1 insertions, 4 deletions

diff --git a/src/include/parser/parse_clause.h b/src/include/parser/parse_clause.h
index 357a2947cb5..ffea3466b5c 100644
--- a/src/include/parser/parse_clause.h
+++ b/src/include/parser/parse_clause.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/parser/parse_clause.h,v 1.51 2008/08/02 21:32:01 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/parser/parse_clause.h,v 1.52 2008/08/07 01:11:52 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -35,9 +35,6 @@ extern List *transformDistinctClause(ParseState *pstate,
 extern List *transformDistinctOnClause(ParseState *pstate, List *distinctlist,
 						List **targetlist, List *sortClause);
 
-extern List *addTargetToGroupList(ParseState *pstate, TargetEntry *tle,
-					 List *grouplist, List *targetlist,
-					 bool requireSortOp, bool resolveUnknown);
 extern Index assignSortGroupRef(TargetEntry *tle, List *tlist);
 extern bool targetIsInSortList(TargetEntry *tle, Oid sortop, List *sortList);