Index: src/backend/nodes/outfuncs.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/nodes/outfuncs.c,v
retrieving revision 1.355
diff -c -r1.355 outfuncs.c
*** src/backend/nodes/outfuncs.c	21 Mar 2009 00:04:39 -0000	1.355
--- src/backend/nodes/outfuncs.c	26 Mar 2009 15:19:43 -0000
***************
*** 1448,1453 ****
--- 1448,1454 ----
  	_outJoinPathInfo(str, (JoinPath *) node);
  
  	WRITE_NODE_FIELD(path_hashclauses);
+ 	WRITE_INT_FIELD(num_batches);
  }
  
  static void
Index: src/backend/optimizer/path/costsize.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v
retrieving revision 1.205
diff -c -r1.205 costsize.c
*** src/backend/optimizer/path/costsize.c	21 Mar 2009 00:04:39 -0000	1.205
--- src/backend/optimizer/path/costsize.c	26 Mar 2009 15:19:43 -0000
***************
*** 1880,1885 ****
--- 1880,1887 ----
  							&numbatches,
  							&num_skew_mcvs);
  	virtualbuckets = (double) numbuckets *(double) numbatches;
+ 	/* mark the path with estimated # of batches */
+ 	path->num_batches = numbatches;
  
  	/*
  	 * Determine bucketsize fraction for inner relation.  We use the smallest
Index: src/backend/optimizer/plan/createplan.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v
retrieving revision 1.256
diff -c -r1.256 createplan.c
*** src/backend/optimizer/plan/createplan.c	21 Mar 2009 00:04:39 -0000	1.256
--- src/backend/optimizer/plan/createplan.c	26 Mar 2009 15:19:44 -0000
***************
*** 1910,1915 ****
--- 1910,1919 ----
  	/* We don't want any excess columns in the hashed tuples */
  	disuse_physical_tlist(inner_plan, best_path->jpath.innerjoinpath);
  
+ 	/* If we expect batching, suppress excess columns in outer tuples too */
+ 	if (best_path->num_batches > 1)
+ 		disuse_physical_tlist(outer_plan, best_path->jpath.outerjoinpath);
+ 
  	/*
  	 * If there is a single join clause and we can identify the outer
  	 * variable as a simple column reference, supply its identity for
Index: src/backend/optimizer/util/pathnode.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/optimizer/util/pathnode.c,v
retrieving revision 1.150
diff -c -r1.150 pathnode.c
*** src/backend/optimizer/util/pathnode.c	27 Feb 2009 00:06:27 -0000	1.150
--- src/backend/optimizer/util/pathnode.c	26 Mar 2009 15:19:44 -0000
***************
*** 1480,1488 ****
  	pathnode->jpath.outerjoinpath = outer_path;
  	pathnode->jpath.innerjoinpath = inner_path;
  	pathnode->jpath.joinrestrictinfo = restrict_clauses;
! 	/* A hashjoin never has pathkeys, since its ordering is unpredictable */
  	pathnode->jpath.path.pathkeys = NIL;
  	pathnode->path_hashclauses = hashclauses;
  
  	cost_hashjoin(pathnode, root, sjinfo);
  
--- 1480,1499 ----
  	pathnode->jpath.outerjoinpath = outer_path;
  	pathnode->jpath.innerjoinpath = inner_path;
  	pathnode->jpath.joinrestrictinfo = restrict_clauses;
! 	/*
! 	 * A hashjoin never has pathkeys, since its output ordering is
! 	 * unpredictable due to possible batching.  XXX If the inner relation is
! 	 * small enough, we could instruct the executor that it must not batch,
! 	 * and then we could assume that the output inherits the outer relation's
! 	 * ordering, which might save a sort step.  However there is considerable
! 	 * downside if our estimate of the inner relation size is badly off.
! 	 * For the moment we don't risk it.  (Note also that if we wanted to take
! 	 * this seriously, joinpath.c would have to consider many more paths for
! 	 * the outer rel than it does now.)
! 	 */
  	pathnode->jpath.path.pathkeys = NIL;
  	pathnode->path_hashclauses = hashclauses;
+ 	/* cost_hashjoin will fill in pathnode->num_batches */
  
  	cost_hashjoin(pathnode, root, sjinfo);
  
Index: src/include/nodes/relation.h
===================================================================
RCS file: /cvsroot/pgsql/src/include/nodes/relation.h,v
retrieving revision 1.170
diff -c -r1.170 relation.h
*** src/include/nodes/relation.h	5 Mar 2009 23:06:45 -0000	1.170
--- src/include/nodes/relation.h	26 Mar 2009 15:19:44 -0000
***************
*** 845,850 ****
--- 845,851 ----
  {
  	JoinPath	jpath;
  	List	   *path_hashclauses;		/* join clauses used for hashing */
+ 	int			num_batches;			/* number of batches expected */
  } HashPath;
  
  /*