Index: src/backend/access/heap/hio.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/access/heap/hio.c,v
retrieving revision 1.78
diff -c -r1.78 hio.c
*** src/backend/access/heap/hio.c	9 Feb 2010 21:43:29 -0000	1.78
--- src/backend/access/heap/hio.c	31 May 2010 20:44:29 -0000
***************
*** 354,384 ****
  	 * is empty (this should never happen, but if it does we don't want to
  	 * risk wiping out valid data).
  	 */
  	page = BufferGetPage(buffer);
  
  	if (!PageIsNew(page))
  		elog(ERROR, "page %u of relation \"%s\" should be empty but is not",
! 			 BufferGetBlockNumber(buffer),
! 			 RelationGetRelationName(relation));
  
  	PageInit(page, BufferGetPageSize(buffer), 0);
  
! 	if (len > PageGetHeapFreeSpace(page))
  	{
  		/* We should not get here given the test at the top */
  		elog(PANIC, "tuple is too big: size %lu", (unsigned long) len);
  	}
  
  	/*
  	 * Remember the new page as our target for future insertions.
- 	 *
- 	 * XXX should we enter the new page into the free space map immediately,
- 	 * or just keep it for this backend's exclusive use in the short run
- 	 * (until VACUUM sees it)?	Seems to depend on whether you expect the
- 	 * current backend to make more insertions or not, which is probably a
- 	 * good bet most of the time.  So for now, don't add it to FSM yet.
  	 */
! 	RelationSetTargetBlock(relation, BufferGetBlockNumber(buffer));
  
  	return buffer;
  }
--- 354,388 ----
  	 * is empty (this should never happen, but if it does we don't want to
  	 * risk wiping out valid data).
  	 */
+ 	targetBlock = BufferGetBlockNumber(buffer);
  	page = BufferGetPage(buffer);
  
  	if (!PageIsNew(page))
  		elog(ERROR, "page %u of relation \"%s\" should be empty but is not",
! 			 targetBlock, RelationGetRelationName(relation));
  
  	PageInit(page, BufferGetPageSize(buffer), 0);
  
! 	pageFreeSpace = PageGetHeapFreeSpace(page);
! 	if (len > pageFreeSpace)
  	{
  		/* We should not get here given the test at the top */
  		elog(PANIC, "tuple is too big: size %lu", (unsigned long) len);
  	}
  
  	/*
+ 	 * If using FSM, mark the page in FSM as having whatever amount of
+ 	 * free space will be left after our insertion.  This is needed so that
+ 	 * the free space won't be forgotten about if this backend doesn't use
+ 	 * it up before exiting or flushing the rel's relcache entry.
+ 	 */
+ 	if (use_fsm)
+ 		RecordPageWithFreeSpace(relation, targetBlock, pageFreeSpace - len);
+ 
+ 	/*
  	 * Remember the new page as our target for future insertions.
  	 */
! 	RelationSetTargetBlock(relation, targetBlock);
  
  	return buffer;
  }