Index: indexam.c
===================================================================
RCS file: /projects/cvsroot/pgsql/src/backend/access/index/indexam.c,v
retrieving revision 1.93
diff -c -r1.93 indexam.c
*** indexam.c	7 May 2006 01:21:30 -0000	1.93
--- indexam.c	6 Jun 2006 01:53:41 -0000
***************
*** 503,517 ****
  		 * to not return it on future indexscans.
  		 *
  		 * We told heap_release_fetch to keep a pin on the buffer, so we can
! 		 * re-access the tuple here.  But we must re-lock the buffer first.
  		 */
- 		LockBuffer(scan->xs_cbuf, BUFFER_LOCK_SHARE);
- 
  		if (HeapTupleSatisfiesVacuum(heapTuple->t_data, RecentGlobalXmin,
  									 scan->xs_cbuf) == HEAPTUPLE_DEAD)
  			scan->kill_prior_tuple = true;
- 
- 		LockBuffer(scan->xs_cbuf, BUFFER_LOCK_UNLOCK);
  	}
  
  	/* Success exit */
--- 503,513 ----
  		 * to not return it on future indexscans.
  		 *
  		 * We told heap_release_fetch to keep a pin on the buffer, so we can
! 		 * re-access the tuple here without re-lock the buffer.
  		 */
  		if (HeapTupleSatisfiesVacuum(heapTuple->t_data, RecentGlobalXmin,
  									 scan->xs_cbuf) == HEAPTUPLE_DEAD)
  			scan->kill_prior_tuple = true;
  	}
  
  	/* Success exit */
Index: nbtinsert.c
===================================================================
RCS file: /projects/cvsroot/pgsql/src/backend/access/nbtree/nbtinsert.c,v
retrieving revision 1.137
diff -c -r1.137 nbtinsert.c
*** nbtinsert.c	8 May 2006 00:00:09 -0000	1.137
--- nbtinsert.c	6 Jun 2006 01:54:55 -0000
***************
*** 255,261 ****
  					 * killed.	This logic should match index_getnext and
  					 * btgettuple.
  					 */
- 					LockBuffer(hbuffer, BUFFER_LOCK_SHARE);
  					if (HeapTupleSatisfiesVacuum(htup.t_data, RecentGlobalXmin,
  												 hbuffer) == HEAPTUPLE_DEAD)
  					{
--- 255,260 ----
***************
*** 265,271 ****
  						else
  							SetBufferCommitInfoNeedsSave(buf);
  					}
- 					LockBuffer(hbuffer, BUFFER_LOCK_UNLOCK);
  				}
  				ReleaseBuffer(hbuffer);
  			}
--- 264,269 ----
Index: bufmgr.c
===================================================================
RCS file: /projects/cvsroot/pgsql/src/backend/storage/buffer/bufmgr.c,v
retrieving revision 1.207
diff -c -r1.207 bufmgr.c
*** bufmgr.c	14 Apr 2006 03:38:55 -0000	1.207
--- bufmgr.c	6 Jun 2006 02:07:09 -0000
***************
*** 1686,1693 ****
  	bufHdr = &BufferDescriptors[buffer - 1];
  
  	Assert(PrivateRefCount[buffer - 1] > 0);
- 	/* here, either share or exclusive lock is OK */
- 	Assert(LWLockHeldByMe(bufHdr->content_lock));
  
  	/*
  	 * This routine might get called many times on the same page, if we are
--- 1686,1691 ----
Index: README
===================================================================
RCS file: /projects/cvsroot/pgsql/src/backend/storage/buffer/README,v
retrieving revision 1.9
diff -c -r1.9 README
*** README	31 Mar 2006 23:32:06 -0000	1.9
--- README	6 Jun 2006 02:22:25 -0000
***************
*** 64,70 ****
  manage to be a conflict it would merely mean that one bit-update would
  be lost and need to be done again later.  These four bits are only hints
  (they cache the results of transaction status lookups in pg_clog), so no
! great harm is done if they get reset to zero by conflicting updates.
  
  5. To physically remove a tuple or compact free space on a page, one
  must hold a pin and an exclusive lock, *and* observe while holding the
--- 64,73 ----
  manage to be a conflict it would merely mean that one bit-update would
  be lost and need to be done again later.  These four bits are only hints
  (they cache the results of transaction status lookups in pg_clog), so no
! great harm is done if they get reset to zero by conflicting updates. If
! you can guarantee there is no vacuum process (see rule #5) on the page,
! then it is safe to just hold the pin and do the changes. In practice, a 
! pin/lock/unlock sequence can make sure of that.
  
  5. To physically remove a tuple or compact free space on a page, one
  must hold a pin and an exclusive lock, *and* observe while holding the