*** pgsql/src/backend/access/transam/multixact.c	2009/11/23 09:58:36	1.32
--- pgsql/src/backend/access/transam/multixact.c	2009/12/19 01:32:33	1.33
***************
*** 42,48 ****
   * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
!  * $PostgreSQL: pgsql/src/backend/access/transam/multixact.c,v 1.31 2009/06/26 20:29:04 tgl Exp $
   *
   *-------------------------------------------------------------------------
   */
--- 42,48 ----
   * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
   * Portions Copyright (c) 1994, Regents of the University of California
   *
!  * $PostgreSQL: pgsql/src/backend/access/transam/multixact.c,v 1.32 2009/11/23 09:58:36 heikki Exp $
   *
   *-------------------------------------------------------------------------
   */
***************
*** 59,64 ****
--- 59,65 ----
  #include "storage/backendid.h"
  #include "storage/lmgr.h"
  #include "storage/procarray.h"
+ #include "utils/builtins.h"
  #include "utils/memutils.h"
  
  
*************** static MultiXactId GetNewMultiXactId(int
*** 220,226 ****
  static MultiXactId mXactCacheGetBySet(int nxids, TransactionId *xids);
  static int	mXactCacheGetById(MultiXactId multi, TransactionId **xids);
  static void mXactCachePut(MultiXactId multi, int nxids, TransactionId *xids);
- static int	xidComparator(const void *arg1, const void *arg2);
  
  #ifdef MULTIXACT_DEBUG
  static char *mxid_to_string(MultiXactId multi, int nxids, TransactionId *xids);
--- 221,226 ----
*************** mXactCachePut(MultiXactId multi, int nxi
*** 1221,1247 ****
  	MXactCache = entry;
  }
  
- /*
-  * xidComparator
-  *		qsort comparison function for XIDs
-  *
-  * We don't need to use wraparound comparison for XIDs, and indeed must
-  * not do so since that does not respect the triangle inequality!  Any
-  * old sort order will do.
-  */
- static int
- xidComparator(const void *arg1, const void *arg2)
- {
- 	TransactionId xid1 = *(const TransactionId *) arg1;
- 	TransactionId xid2 = *(const TransactionId *) arg2;
- 
- 	if (xid1 > xid2)
- 		return 1;
- 	if (xid1 < xid2)
- 		return -1;
- 	return 0;
- }
- 
  #ifdef MULTIXACT_DEBUG
  static char *
  mxid_to_string(MultiXactId multi, int nxids, TransactionId *xids)
--- 1221,1226 ----
*************** multixact_redo(XLogRecPtr lsn, XLogRecor
*** 2051,2061 ****
--- 2030,2047 ----
  			if (TransactionIdPrecedes(max_xid, xids[i]))
  				max_xid = xids[i];
  		}
+ 
+ 		/* We don't expect anyone else to modify nextXid, hence startup process
+ 		 * doesn't need to hold a lock while checking this. We still acquire
+ 		 * the lock to modify it, though.
+ 		 */
  		if (TransactionIdFollowsOrEquals(max_xid,
  										 ShmemVariableCache->nextXid))
  		{
+ 			LWLockAcquire(XidGenLock, LW_EXCLUSIVE);
  			ShmemVariableCache->nextXid = max_xid;
  			TransactionIdAdvance(ShmemVariableCache->nextXid);
+ 			LWLockRelease(XidGenLock);
  		}
  	}
  	else