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Code Issues Releases Wiki Activity

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.
This commit is contained in:
Vadim B. Mikheev 1999-06-10 14:17:12 +00:00
parent c37ecaf8d5
commit 78f7ccc982
7 changed files with 40 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
src/backend/access/heap/heapam.c
View File

@ -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;

21
src/backend/access/transam/transam.c
View File

@ -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;
}

5
src/backend/access/transam/xact.c
View File

@ -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;

4
src/backend/commands/vacuum.c
View File

@ -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... */

5
src/backend/storage/buffer/bufmgr.c
View File

@ -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;

4
src/backend/storage/lmgr/lmgr.c
View File

@ -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.

3
src/include/access/transam.h
View File

@ -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);