Index: src/backend/access/transam/transam.c
===================================================================
RCS file: /home/sriggs/pg/REPOSITORY/pgsql/src/backend/access/transam/transam.c,v
retrieving revision 1.73
diff -c -r1.73 transam.c
*** src/backend/access/transam/transam.c	1 Jan 2008 19:45:48 -0000	1.73
--- src/backend/access/transam/transam.c	5 Feb 2008 12:21:51 -0000
***************
*** 262,267 ****
--- 262,283 ----
  	return false;
  }
  
+ bool
+ TransactionIdIsKnownNotInProgress(TransactionId transactionId)
+ {
+ 	if (TransactionIdEquals(transactionId, cachedFetchXid))
+ 	{
+ 		switch (cachedFetchXidStatus)
+ 		{
+ 			case TRANSACTION_STATUS_COMMITTED:
+ 			case TRANSACTION_STATUS_ABORTED:
+ 				return true;
+ 		}
+ 	}
+ 
+ 	return false;
+ }
+ 
  /* --------------------------------
   *		TransactionId Commit
   *		TransactionId Abort
Index: src/backend/storage/ipc/procarray.c
===================================================================
RCS file: /home/sriggs/pg/REPOSITORY/pgsql/src/backend/storage/ipc/procarray.c,v
retrieving revision 1.40
diff -c -r1.40 procarray.c
*** src/backend/storage/ipc/procarray.c	9 Jan 2008 21:52:36 -0000	1.40
--- src/backend/storage/ipc/procarray.c	5 Feb 2008 12:21:12 -0000
***************
*** 61,66 ****
--- 61,67 ----
  /* counters for XidCache measurement */
  static long xc_by_recent_xmin = 0;
  static long xc_by_my_xact = 0;
+ static long xc_by_known_xact = 0;
  static long xc_by_latest_xid = 0;
  static long xc_by_main_xid = 0;
  static long xc_by_child_xid = 0;
***************
*** 69,74 ****
--- 70,76 ----
  
  #define xc_by_recent_xmin_inc()		(xc_by_recent_xmin++)
  #define xc_by_my_xact_inc()			(xc_by_my_xact++)
+ #define xc_by_known_xact_inc()		(xc_by_known_xact++)
  #define xc_by_latest_xid_inc()		(xc_by_latest_xid++)
  #define xc_by_main_xid_inc()		(xc_by_main_xid++)
  #define xc_by_child_xid_inc()		(xc_by_child_xid++)
***************
*** 80,85 ****
--- 82,88 ----
  
  #define xc_by_recent_xmin_inc()		((void) 0)
  #define xc_by_my_xact_inc()			((void) 0)
+ #define xc_by_known_xact_inc()		((void) 0)
  #define xc_by_latest_xid_inc()		((void) 0)
  #define xc_by_main_xid_inc()		((void) 0)
  #define xc_by_child_xid_inc()		((void) 0)
***************
*** 364,369 ****
--- 367,382 ----
  	}
  
  	/*
+ 	 * We may have just checked the status of this transaction, so if it is
+ 	 * already known to be not in progress, take a fastpath out
+ 	 */
+ 	if (TransactionIdIsKnownNotInProgress(xid))
+ 	{
+ 		xc_by_known_xact_inc();
+ 		return false;
+ 	}
+ 
+ 	/*
  	 * If not first time through, get workspace to remember main XIDs in. We
  	 * malloc it permanently to avoid repeated palloc/pfree overhead.
  	 */
***************
*** 1335,1343 ****
  DisplayXidCache(void)
  {
  	fprintf(stderr,
! 			"XidCache: xmin: %ld, myxact: %ld, latest: %ld, mainxid: %ld, childxid: %ld, nooflo: %ld, slow: %ld\n",
  			xc_by_recent_xmin,
  			xc_by_my_xact,
  			xc_by_latest_xid,
  			xc_by_main_xid,
  			xc_by_child_xid,
--- 1348,1357 ----
  DisplayXidCache(void)
  {
  	fprintf(stderr,
! 			"XidCache: xmin: %ld, myxact: %ld, known: %ld, latest: %ld, mainxid: %ld, childxid: %ld, nooflo: %ld, slow: %ld\n",
  			xc_by_recent_xmin,
  			xc_by_my_xact,
+ 			xc_by_known_xact,
  			xc_by_latest_xid,
  			xc_by_main_xid,
  			xc_by_child_xid,
Index: src/include/access/transam.h
===================================================================
RCS file: /home/sriggs/pg/REPOSITORY/pgsql/src/include/access/transam.h,v
retrieving revision 1.64
diff -c -r1.64 transam.h
*** src/include/access/transam.h	1 Jan 2008 19:45:56 -0000	1.64
--- src/include/access/transam.h	5 Feb 2008 12:21:12 -0000
***************
*** 138,143 ****
--- 138,144 ----
   */
  extern bool TransactionIdDidCommit(TransactionId transactionId);
  extern bool TransactionIdDidAbort(TransactionId transactionId);
+ extern bool TransactionIdIsKnownNotInProgress(TransactionId transactionId);
  extern void TransactionIdCommit(TransactionId transactionId);
  extern void TransactionIdAsyncCommit(TransactionId transactionId, XLogRecPtr lsn);
  extern void TransactionIdAbort(TransactionId transactionId);