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.

4 files changed, 8 insertions, 4 deletions

diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 652c726a67..e562949d93 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -15,7 +15,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.396 2008/08/02 21:31:59 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.397 2008/08/07 01:11:46 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1943,6 +1943,7 @@ _copySetOperationStmt(SetOperationStmt *from)
 	COPY_NODE_FIELD(rarg);
 	COPY_NODE_FIELD(colTypes);
 	COPY_NODE_FIELD(colTypmods);
+	COPY_NODE_FIELD(groupClauses);
 
 	return newnode;
 }
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 4e011947ef..dc0b2cca37 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -18,7 +18,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.325 2008/08/02 21:31:59 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.326 2008/08/07 01:11:47 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -839,6 +839,7 @@ _equalSetOperationStmt(SetOperationStmt *a, SetOperationStmt *b)
 	COMPARE_NODE_FIELD(rarg);
 	COMPARE_NODE_FIELD(colTypes);
 	COMPARE_NODE_FIELD(colTypmods);
+	COMPARE_NODE_FIELD(groupClauses);
 
 	return true;
 }
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 408b9b2a75..26f8fb3810 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.330 2008/08/05 02:43:17 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.331 2008/08/07 01:11:48 tgl Exp $
  *
  * NOTES
  *	  Every node type that can appear in stored rules' parsetrees *must*
@@ -1780,6 +1780,7 @@ _outSetOperationStmt(StringInfo str, SetOperationStmt *node)
 	WRITE_NODE_FIELD(rarg);
 	WRITE_NODE_FIELD(colTypes);
 	WRITE_NODE_FIELD(colTypmods);
+	WRITE_NODE_FIELD(groupClauses);
 }
 
 static void
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index e7de4898c0..c46593d22c 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.211 2008/08/02 21:31:59 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.212 2008/08/07 01:11:49 tgl Exp $
  *
  * NOTES
  *	  Path and Plan nodes do not have any readfuncs support, because we
@@ -232,6 +232,7 @@ _readSetOperationStmt(void)
 	READ_NODE_FIELD(rarg);
 	READ_NODE_FIELD(colTypes);
 	READ_NODE_FIELD(colTypmods);
+	READ_NODE_FIELD(groupClauses);
 
 	READ_DONE();
 }