Index: src/backend/utils/sort/tuplesort.c
===================================================================
RCS file: /home/stark/src/REPOSITORY/pgsql/src/backend/utils/sort/tuplesort.c,v
retrieving revision 1.77
diff -c -r1.77 tuplesort.c
*** src/backend/utils/sort/tuplesort.c	7 Jun 2007 19:19:57 -0000	1.77
--- src/backend/utils/sort/tuplesort.c	1 Sep 2007 20:31:53 -0000
***************
*** 940,946 ****
  			 */
  			if (state->bounded &&
  				(state->memtupcount > state->bound * 2 ||
! 				 (state->memtupcount > state->bound && LACKMEM(state))))
  			{
  #ifdef TRACE_SORT
  				if (trace_sort)
--- 940,946 ----
  			 */
  			if (state->bounded &&
  				(state->memtupcount > state->bound * 2 ||
! 				 (state->memtupcount > state->bound * 1.1 && LACKMEM(state))))
  			{
  #ifdef TRACE_SORT
  				if (trace_sort)
***************
*** 970,975 ****
--- 970,976 ----
  			break;
  
  		case TSS_BOUNDED:
+ 
  			/*
  			 * We don't want to grow the array here, so check whether the
  			 * new tuple can be discarded before putting it in.  This should
***************
*** 991,996 ****
--- 992,1009 ----
  				tuplesort_heap_siftup(state, false);
  				tuplesort_heap_insert(state, tuple, 0, false);
  			}
+ 
+ 			/* If the later tuples were larger than the first batch we could be
+ 			 * low on memory in which case we have to give up on the bounded
+ 			 * sort and fail over to a disk sort 
+ 			 */
+ 			if (LACKMEM(state)) 
+ 			{
+ 				REVERSEDIRECTION(state);
+ 				inittapes(state);
+ 				dumptuples(state, false);
+ 			}
+ 
  			break;
  
  		case TSS_BUILDRUNS:
***************
*** 1068,1075 ****
  			 * in memory, using a heap to eliminate excess tuples.  Now we have
  			 * to transform the heap to a properly-sorted array.
  			 */
! 			if (state->memtupcount > 1)
! 				sort_bounded_heap(state);
  			state->current = 0;
  			state->eof_reached = false;
  			state->markpos_offset = 0;
--- 1081,1087 ----
  			 * in memory, using a heap to eliminate excess tuples.  Now we have
  			 * to transform the heap to a properly-sorted array.
  			 */
! 			sort_bounded_heap(state);
  			state->current = 0;
  			state->eof_reached = false;
  			state->markpos_offset = 0;