1. Fix for elog(ERROR, "EvalPlanQual: t_xmin is uncommitted ?!")

   and possibly for other cases too:

   DO NOT cache status of transaction in unknown state
   (i.e. non-committed and non-aborted ones)

   Example:
   T1 reads row updated/inserted by running T2 and cache T2 status.
   T2 commits.
   Now T1 reads a row updated by T2 and with HEAP_XMAX_COMMITTED
   in t_infomask (so cached T2 status is not changed).
   Now T1 EvalPlanQual gets updated row version without HEAP_XMIN_COMMITTED
   -> TransactionIdDidCommit(t_xmin) and TransactionIdDidAbort(t_xmin)
   return FALSE and T2 decides that t_xmin is not committed and gets
   ERROR above.

   It's too late to find more smart way to handle such cases and so
   I just changed xact status caching and got rid TransactionIdFlushCache()
   from code.

   Changed: transam.c, xact.c, lmgr.c and transam.h - last three
   just because of TransactionIdFlushCache() is removed.

2. heapam.c:

   T1 marked a row for update. T2 waits for T1 commit/abort.
   T1 commits. T3 updates the row before T2 locks row page.
   Now T2 sees that new row t_xmax is different from xact id (T1)
   T2 was waiting for. Old code did Assert here. New one goes to
   HeapTupleSatisfiesUpdate. Obvious changes too.

3. Added Assert to vacuum.c
4. bufmgr.c: break
   Assert(buf->r_locks == 0 && !buf->ri_lock)
   into two Asserts.

diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 1ea78ec86333c7fa347b7656e9fb6911f0e62d7b..39f6d223ebd3e345b31c4fa8c0de5413089c9811 100644 (file)
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/access/heap/heapam.c,v 1.43 1999/05/25 16:07:04 momjian Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/access/heap/heapam.c,v 1.44 1999/06/10 14:17:05 vadim Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -1152,8 +1152,13 @@ l1:
                LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
                if (TransactionIdDidAbort(xwait))
                        goto l1;
-               /* concurrent xact committed */
-               Assert(tp.t_data->t_xmax == xwait);
+               /* 
+                * xwait is committed but if xwait had just marked
+                * the tuple for update then some other xaction could 
+                * update this tuple before we got to this point.
+                */
+               if (tp.t_data->t_xmax != xwait)
+                       goto l1;
                if (!(tp.t_data->t_infomask & HEAP_XMAX_COMMITTED))
                {
                        tp.t_data->t_infomask |= HEAP_XMAX_COMMITTED;
@@ -1242,8 +1247,13 @@ l2:
                LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
                if (TransactionIdDidAbort(xwait))
                        goto l2;
-               /* concurrent xact committed */
-               Assert(oldtup.t_data->t_xmax == xwait);
+               /* 
+                * xwait is committed but if xwait had just marked
+                * the tuple for update then some other xaction could 
+                * update this tuple before we got to this point.
+                */
+               if (oldtup.t_data->t_xmax != xwait)
+                       goto l2;
                if (!(oldtup.t_data->t_infomask & HEAP_XMAX_COMMITTED))
                {
                        oldtup.t_data->t_infomask |= HEAP_XMAX_COMMITTED;
@@ -1359,8 +1369,13 @@ l3:
                LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE);
                if (TransactionIdDidAbort(xwait))
                        goto l3;
-               /* concurrent xact committed */
-               Assert(tuple->t_data->t_xmax == xwait);
+               /* 
+                * xwait is committed but if xwait had just marked
+                * the tuple for update then some other xaction could 
+                * update this tuple before we got to this point.
+                */
+               if (tuple->t_data->t_xmax != xwait)
+                       goto l3;
                if (!(tuple->t_data->t_infomask & HEAP_XMAX_COMMITTED))
                {
                        tuple->t_data->t_infomask |= HEAP_XMAX_COMMITTED;

diff --git a/src/backend/access/transam/transam.c b/src/backend/access/transam/transam.c
index fe1d57d769c0945d1e30137727eb5b4a35b1e4c0..03bb786f4b068eb4f93c083583bf1e8eaad4ce07 100644 (file)
--- a/src/backend/access/transam/transam.c
+++ b/src/backend/access/transam/transam.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/access/transam/transam.c,v 1.26 1999/05/25 16:07:45 momjian Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/access/transam/transam.c,v 1.27 1999/06/10 14:17:06 vadim Exp $
  *
  * NOTES
  *       This file contains the high level access-method interface to the
@@ -172,8 +172,14 @@ TransactionLogTest(TransactionId transactionId, /* transaction id to test */
 
        if (!fail)
        {
-               TransactionIdStore(transactionId, &cachedTestXid);
-               cachedTestXidStatus = xidstatus;
+               /*
+                * DO NOT cache status for transactions in unknown state !!!
+                */
+               if (xidstatus == XID_COMMIT || xidstatus == XID_ABORT)
+               {
+                       TransactionIdStore(transactionId, &cachedTestXid);
+                       cachedTestXidStatus = xidstatus;
+               }
                return (bool) (status == xidstatus);
        }
 
@@ -576,12 +582,3 @@ TransactionIdAbort(TransactionId transactionId)
 
        TransactionLogUpdate(transactionId, XID_ABORT);
 }
-
-void
-TransactionIdFlushCache()
-{
-
-       TransactionIdStore(AmiTransactionId, &cachedTestXid);
-       cachedTestXidStatus = XID_COMMIT;
-
-}

diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index d03136b5085f350d5dd371f293fb462eedbc6958..4689a2f82ea0047cdbebd46c369435313ed33fa7 100644 (file)
--- 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 1.40 1999/06/06 20:19:34 vadim Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.41 1999/06/10 14:17:06 vadim Exp $
  *
  * NOTES
  *             Transaction aborts can now occur two ways:
@@ -514,8 +514,6 @@ CommandCounterIncrement()
        AtCommit_Cache();
        AtStart_Cache();
 
-       TransactionIdFlushCache();
-
 }
 
 void
@@ -822,7 +820,6 @@ StartTransaction()
 {
        TransactionState s = CurrentTransactionState;
 
-       TransactionIdFlushCache();
        FreeXactSnapshot();
        XactIsoLevel = DefaultXactIsoLevel;
 

diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index 7c1a8cd600125dbacd670a76989c4d8df22d4284..bfc9094b4827a661b6a36ecc5c163d8f616be1f9 100644 (file)
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.107 1999/06/06 20:19:34 vadim Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.108 1999/06/10 14:17:07 vadim Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1351,6 +1351,8 @@ vc_rpfheap(VRelStats *vacrelstats, Relation onerel,
                                                if (!ItemIdIsUsed(Pitemid))
                                                        elog(ERROR, "Parent itemid marked as unused");
                                                Ptp.t_data = (HeapTupleHeader) PageGetItem(Ppage, Pitemid);
+                                               Assert(ItemPointerEquals(&(vtld.new_tid),
+                                                                                               &(Ptp.t_data->t_ctid)));
                                                Assert(Ptp.t_data->t_xmax == tp.t_data->t_xmin);
 
 #ifdef NOT_USED                        /* I'm not sure that this will wotk properly... */

diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 9b7a41b4cb822f846efd8821b2e4ad57c740745b..f0b397dbea447719258f7aa0927ffb0d22d45a7d 100644 (file)
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/storage/buffer/bufmgr.c,v 1.53 1999/05/29 03:58:43 tgl Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/storage/buffer/bufmgr.c,v 1.54 1999/06/10 14:17:09 vadim Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2007,7 +2007,8 @@ LockBuffer(Buffer buffer, int mode)
                else if (BufferLocks[buffer - 1] & BL_W_LOCK)
                {
                        Assert(buf->w_lock);
-                       Assert(buf->r_locks == 0 && !buf->ri_lock);
+                       Assert(buf->r_locks == 0);
+                       Assert(!buf->ri_lock);
                        Assert(!(BufferLocks[buffer - 1] & (BL_R_LOCK | BL_RI_LOCK)))
                                buf->w_lock = false;
                        BufferLocks[buffer - 1] &= ~BL_W_LOCK;

diff --git a/src/backend/storage/lmgr/lmgr.c b/src/backend/storage/lmgr/lmgr.c
index f7ab4acffb4cf2850d40f1c8bbd4f42abca0de71..58ee47fe611bf4b600098b67a6ffc89cbcd708db 100644 (file)
--- a/src/backend/storage/lmgr/lmgr.c
+++ b/src/backend/storage/lmgr/lmgr.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lmgr.c,v 1.26 1999/05/31 01:48:13 vadim Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lmgr.c,v 1.27 1999/06/10 14:17:11 vadim Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -324,8 +324,6 @@ XactLockTableWait(TransactionId xid)
        LockAcquire(LockTableId, &tag, ShareLock);
        LockRelease(LockTableId, &tag, ShareLock);
 
-       TransactionIdFlushCache();
-
        /*
         * Transaction was committed/aborted/crashed - we have to update
         * pg_log if transaction is still marked as running.

diff --git a/src/include/access/transam.h b/src/include/access/transam.h
index 23fc2b59f0bbdb00c82f5c4ac85958b13dd79af5..2551278f12965f0017b5349eb4c36401b07f2f8d 100644 (file)
--- a/src/include/access/transam.h
+++ b/src/include/access/transam.h
@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: transam.h,v 1.21 1999/05/25 22:42:35 momjian Exp $
+ * $Id: transam.h,v 1.22 1999/06/10 14:17:12 vadim Exp $
  *
  *      NOTES
  *             Transaction System Version 101 now support proper oid
@@ -145,7 +145,6 @@ extern bool TransactionIdDidCommit(TransactionId transactionId);
 extern bool TransactionIdDidAbort(TransactionId transactionId);
 extern void TransactionIdCommit(TransactionId transactionId);
 extern void TransactionIdAbort(TransactionId transactionId);
-extern void TransactionIdFlushCache(void);
 
 /* in transam/transsup.c */
 extern void AmiTransactionOverride(bool flag);