Redefine IsTransactionState() to only return true for TRANS_INPROGRESS state,

which is the only state in which it's safe to initiate database queries.
It turns out that all but two of the callers thought that's what it meant;
and the other two were using it as a proxy for "will GetTopTransactionId()
return a nonzero XID"?  Since it was in fact an unreliable guide to that,
make those two just invoke GetTopTransactionId() always, then deal with a
zero result if they get one.

1 files changed, 3 insertions, 4 deletions

diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index 287d3b4ee56..9d290ba9739 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -23,7 +23,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/storage/ipc/procarray.c,v 1.25 2007/06/01 19:38:07 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/storage/ipc/procarray.c,v 1.26 2007/06/07 21:45:59 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -422,9 +422,8 @@ GetOldestXmin(bool allDbs, bool ignoreVacuum)
 	 * are no xacts running at all, that will be the subtrans truncation
 	 * point!)
 	 */
-	if (IsTransactionState())
-		result = GetTopTransactionId();
-	else
+	result = GetTopTransactionId();
+	if (!TransactionIdIsValid(result))
 		result = ReadNewTransactionId();
 
 	LWLockAcquire(ProcArrayLock, LW_SHARED);