1. Additional fix against ERROR: Child itemid marked as unused

   in CommitTransaction().
2. Changes in GetSnapshotData().

1 files changed, 23 insertions, 13 deletions

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6884e635904..6bde05733ac 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.38 1999/06/03 04:41:41 vadim Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.39 1999/06/03 13:33:12 vadim Exp $
  *
  * NOTES
  *		Transaction aborts can now occur two ways:
@@ -646,18 +646,6 @@ RecordTransactionCommit()
 	FlushBufferPool(!TransactionFlushEnabled());
 	if (leak)
 		ResetBufferPool();
-
-	/*
-	 * Let others know about no transaction in progress.
-	 * Note that this must be done _before_ releasing locks
-	 * we hold or bad (too high) XmaxRecent value might be
-	 * used by vacuum.
-	 */
-	if (MyProc != (PROC *) NULL)
-	{
-		MyProc->xid = InvalidTransactionId;
-		MyProc->xmin = InvalidTransactionId;
-	}
 }
 
 
@@ -950,6 +938,28 @@ CommitTransaction()
 	DestroyNoNameRels();
 	AtEOXact_portals();
 	RecordTransactionCommit();
+
+	/*
+	 * Let others know about no transaction in progress by me.
+	 * Note that this must be done _before_ releasing locks we hold 
+	 * and SpinAcquire(ShmemIndexLock) is required - or bad (too high) 
+	 * XmaxRecent value might be used by vacuum: UPDATE with xid 0 is 
+	 * blocked by xid 1' UPDATE, xid 1 is doing commit while xid 2 
+	 * gets snapshot - if xid 2' GetSnapshotData sees xid 1 as running
+	 * then it must see xid 0 as running as well or XmaxRecent = 1
+	 * might be used by concurrent vacuum causing
+	 *         ERROR:  Child itemid marked as unused
+	 * This bug was reported by Hiroshi Inoue and I was able to reproduce
+	 * it with 3 sessions and gdb.	- vadim 06/03/99
+	 */
+	if (MyProc != (PROC *) NULL)
+	{
+		SpinAcquire(ShmemIndexLock);
+		MyProc->xid = InvalidTransactionId;
+		MyProc->xmin = InvalidTransactionId;
+		SpinRelease(ShmemIndexLock);
+	}
+
 	RelationPurgeLocalRelation(true);
 	AtCommit_Cache();
 	AtCommit_Locks();