avoid_Extra_WAL_checkpoint.patch

*** a/src/backend/access/transam/xlog.c
--- b/src/backend/access/transam/xlog.c
***************
*** 7084,7094 **** CreateCheckPoint(int flags)
  				  CHECKPOINT_FORCE)) == 0)
  	{
  		XLogRecPtr	curInsert;
  
  		INSERT_RECPTR(curInsert, Insert, Insert->curridx);
  		if (curInsert == ControlFile->checkPoint + 
  			MAXALIGN(SizeOfXLogRecord + sizeof(CheckPoint)) &&
! 			ControlFile->checkPoint == ControlFile->checkPointCopy.redo)
  		{
  			LWLockRelease(WALInsertLock);
  			LWLockRelease(CheckpointLock);
--- 7084,7110 ----
  				  CHECKPOINT_FORCE)) == 0)
  	{
  		XLogRecPtr	curInsert;
+ 		uint32 runningXactXLog = 0;
  
+ 		/* 
+ 		  * Take the size of RUNNING XACT XLOG, only if HOT STANDBY is enabled.
+ 		  * Because if it is not enabled, then RUNNING XACT XLOG is not logged.
+ 		  */
+ 		if (!shutdown && XLogStandbyInfoActive())
+ 		{
+ 			runningXactXLog = MAXALIGN(MinSizeOfXactRunningXacts) + SizeOfXLogRecord;
+ 		}		
+ 
+ 		/*
+ 		  * ControlFile->checkPointCopy.redo points to the offset before 
+ 		  * RUNNING XACT XLOG was inserted but ControlFile->checkPoint
+ 		  * points to the offset after insertion, so we should add size of RUNNING XACT XLOG
+ 		  * to check if any other new XLOG has been inserted
+ 		  */		  
  		INSERT_RECPTR(curInsert, Insert, Insert->curridx);
  		if (curInsert == ControlFile->checkPoint + 
  			MAXALIGN(SizeOfXLogRecord + sizeof(CheckPoint)) &&
! 			ControlFile->checkPoint == ControlFile->checkPointCopy.redo + runningXactXLog)
  		{
  			LWLockRelease(WALInsertLock);
  			LWLockRelease(CheckpointLock);