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Adjust time qual checking code so that we always check TransactionIdIsInProgress

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before we check commit/abort status.  Formerly this was done in some paths
but not all, with the result that a transaction might be considered
committed for some purposes before it became committed for others.
Per example found by Jan Wieck.
This commit is contained in:
Tom Lane
2005-05-07 21:23:24 +00:00
parent 07e3879c95
commit 4beb9cd5eb
1 changed files with 81 additions and 56 deletions
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137
src/backend/utils/time/tqual.c
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@@ -11,12 +11,26 @@
* containing the tuple. (VACUUM FULL assumes it's sufficient to have
* exclusive lock on the containing relation, instead.)
*
* NOTE: must check TransactionIdIsInProgress (which looks in PGPROC array)
* before TransactionIdDidCommit/TransactionIdDidAbort (which look in
* pg_clog). Otherwise we have a race condition: we might decide that a
* just-committed transaction crashed, because none of the tests succeed.
* xact.c is careful to record commit/abort in pg_clog before it unsets
* MyProc->xid in PGPROC array. That fixes that problem, but it also
* means there is a window where TransactionIdIsInProgress and
* TransactionIdDidCommit will both return true. If we check only
* TransactionIdDidCommit, we could consider a tuple committed when a
* later GetSnapshotData call will still think the originating transaction
* is in progress, which leads to application-level inconsistency. The
* upshot is that we gotta check TransactionIdIsInProgress first in all
* code paths.
*
*
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/time/tqual.c,v 1.61 2002/10/08 17:17:19 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/time/tqual.c,v 1.61.2.1 2005/05/07 21:23:24 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -112,14 +126,16 @@ HeapTupleSatisfiesItself(HeapTupleHeader tuple)
return false;
}
else if (!TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
else if (TransactionIdIsInProgress(HeapTupleHeaderGetXmin(tuple)))
return false;
else if (TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
else
{
if (TransactionIdDidAbort(HeapTupleHeaderGetXmin(tuple)))
tuple->t_infomask |= HEAP_XMIN_INVALID; /* aborted */
/* it must have aborted or crashed */
tuple->t_infomask |= HEAP_XMIN_INVALID;
return false;
}
else
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
}
/* by here, the inserting transaction has committed */
@@ -141,10 +157,13 @@ HeapTupleSatisfiesItself(HeapTupleHeader tuple)
return false;
}
if (TransactionIdIsInProgress(HeapTupleHeaderGetXmax(tuple)))
return true;
if (!TransactionIdDidCommit(HeapTupleHeaderGetXmax(tuple)))
{
if (TransactionIdDidAbort(HeapTupleHeaderGetXmax(tuple)))
tuple->t_infomask |= HEAP_XMAX_INVALID; /* aborted */
/* it must have aborted or crashed */
tuple->t_infomask |= HEAP_XMAX_INVALID;
return true;
}
@@ -254,14 +273,16 @@ HeapTupleSatisfiesNow(HeapTupleHeader tuple)
else
return false; /* deleted before scan started */
}
else if (!TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
else if (TransactionIdIsInProgress(HeapTupleHeaderGetXmin(tuple)))
return false;
else if (TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
else
{
if (TransactionIdDidAbort(HeapTupleHeaderGetXmin(tuple)))
tuple->t_infomask |= HEAP_XMIN_INVALID; /* aborted */
/* it must have aborted or crashed */
tuple->t_infomask |= HEAP_XMIN_INVALID;
return false;
}
else
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
}
/* by here, the inserting transaction has committed */
@@ -286,10 +307,13 @@ HeapTupleSatisfiesNow(HeapTupleHeader tuple)
return false; /* deleted before scan started */
}
if (TransactionIdIsInProgress(HeapTupleHeaderGetXmax(tuple)))
return true;
if (!TransactionIdDidCommit(HeapTupleHeaderGetXmax(tuple)))
{
if (TransactionIdDidAbort(HeapTupleHeaderGetXmax(tuple)))
tuple->t_infomask |= HEAP_XMAX_INVALID; /* aborted */
/* it must have aborted or crashed */
tuple->t_infomask |= HEAP_XMAX_INVALID;
return true;
}
@@ -427,14 +451,16 @@ HeapTupleSatisfiesUpdate(HeapTuple htuple, CommandId curcid)
return HeapTupleInvisible; /* updated before scan
* started */
}
else if (!TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
else if (TransactionIdIsInProgress(HeapTupleHeaderGetXmin(tuple)))
return HeapTupleInvisible;
else if (TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
else
{
if (TransactionIdDidAbort(HeapTupleHeaderGetXmin(tuple)))
tuple->t_infomask |= HEAP_XMIN_INVALID; /* aborted */
/* it must have aborted or crashed */
tuple->t_infomask |= HEAP_XMIN_INVALID;
return HeapTupleInvisible;
}
else
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
}
/* by here, the inserting transaction has committed */
@@ -460,15 +486,14 @@ HeapTupleSatisfiesUpdate(HeapTuple htuple, CommandId curcid)
return HeapTupleInvisible; /* updated before scan started */
}
if (TransactionIdIsInProgress(HeapTupleHeaderGetXmax(tuple)))
return HeapTupleBeingUpdated;
if (!TransactionIdDidCommit(HeapTupleHeaderGetXmax(tuple)))
{
if (TransactionIdDidAbort(HeapTupleHeaderGetXmax(tuple)))
{
tuple->t_infomask |= HEAP_XMAX_INVALID; /* aborted */
return HeapTupleMayBeUpdated;
}
/* running xact */
return HeapTupleBeingUpdated; /* in updation by other */
/* it must have aborted or crashed */
tuple->t_infomask |= HEAP_XMAX_INVALID;
return HeapTupleMayBeUpdated;
}
/* xmax transaction committed */
@@ -549,19 +574,20 @@ HeapTupleSatisfiesDirty(HeapTupleHeader tuple)
return false;
}
else if (!TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
else if (TransactionIdIsInProgress(HeapTupleHeaderGetXmin(tuple)))
{
if (TransactionIdDidAbort(HeapTupleHeaderGetXmin(tuple)))
{
tuple->t_infomask |= HEAP_XMIN_INVALID;
return false;
}
SnapshotDirty->xmin = HeapTupleHeaderGetXmin(tuple);
/* XXX shouldn't we fall through to look at xmax? */
return true; /* in insertion by other */
}
else
else if (TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
else
{
/* it must have aborted or crashed */
tuple->t_infomask |= HEAP_XMIN_INVALID;
return false;
}
}
/* by here, the inserting transaction has committed */
@@ -584,16 +610,17 @@ HeapTupleSatisfiesDirty(HeapTupleHeader tuple)
return false;
}
if (TransactionIdIsInProgress(HeapTupleHeaderGetXmax(tuple)))
{
SnapshotDirty->xmax = HeapTupleHeaderGetXmax(tuple);
return true;
}
if (!TransactionIdDidCommit(HeapTupleHeaderGetXmax(tuple)))
{
if (TransactionIdDidAbort(HeapTupleHeaderGetXmax(tuple)))
{
tuple->t_infomask |= HEAP_XMAX_INVALID; /* aborted */
return true;
}
/* running xact */
SnapshotDirty->xmax = HeapTupleHeaderGetXmax(tuple);
return true; /* in updation by other */
/* it must have aborted or crashed */
tuple->t_infomask |= HEAP_XMAX_INVALID;
return true;
}
/* xmax transaction committed */
@@ -686,14 +713,16 @@ HeapTupleSatisfiesSnapshot(HeapTupleHeader tuple, Snapshot snapshot)
else
return false; /* deleted before scan started */
}
else if (!TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
else if (TransactionIdIsInProgress(HeapTupleHeaderGetXmin(tuple)))
return false;
else if (TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
else
{
if (TransactionIdDidAbort(HeapTupleHeaderGetXmin(tuple)))
tuple->t_infomask |= HEAP_XMIN_INVALID;
/* it must have aborted or crashed */
tuple->t_infomask |= HEAP_XMIN_INVALID;
return false;
}
else
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
}
/*
@@ -733,10 +762,13 @@ HeapTupleSatisfiesSnapshot(HeapTupleHeader tuple, Snapshot snapshot)
return false; /* deleted before scan started */
}
if (TransactionIdIsInProgress(HeapTupleHeaderGetXmax(tuple)))
return true;
if (!TransactionIdDidCommit(HeapTupleHeaderGetXmax(tuple)))
{
if (TransactionIdDidAbort(HeapTupleHeaderGetXmax(tuple)))
tuple->t_infomask |= HEAP_XMAX_INVALID; /* aborted */
/* it must have aborted or crashed */
tuple->t_infomask |= HEAP_XMAX_INVALID;
return true;
}
@@ -785,13 +817,6 @@ HeapTupleSatisfiesVacuum(HeapTupleHeader tuple, TransactionId OldestXmin)
*
* If the inserting transaction aborted, then the tuple was never visible
* to any other transaction, so we can delete it immediately.
*
* NOTE: must check TransactionIdIsInProgress (which looks in PROC array)
* before TransactionIdDidCommit/TransactionIdDidAbort (which look in
* pg_clog). Otherwise we have a race condition where we might decide
* that a just-committed transaction crashed, because none of the
* tests succeed. xact.c is careful to record commit/abort in pg_clog
* before it unsets MyProc->xid in PROC array.
*/
if (!(tuple->t_infomask & HEAP_XMIN_COMMITTED))
{