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Adjust time qual checking code so that we always check TransactionIdIsInProgress
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
parent
68ab4de905
commit
2e6482493a
@ -11,12 +11,26 @@
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* containing the tuple. (VACUUM FULL assumes it's sufficient to have
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* exclusive lock on the containing relation, instead.)
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*
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* NOTE: must check TransactionIdIsInProgress (which looks in PGPROC array)
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* before TransactionIdDidCommit/TransactionIdDidAbort (which look in
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* pg_clog). Otherwise we have a race condition: we might decide that a
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* just-committed transaction crashed, because none of the tests succeed.
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* xact.c is careful to record commit/abort in pg_clog before it unsets
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* MyProc->xid in PGPROC array. That fixes that problem, but it also
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* means there is a window where TransactionIdIsInProgress and
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* TransactionIdDidCommit will both return true. If we check only
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* TransactionIdDidCommit, we could consider a tuple committed when a
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* later GetSnapshotData call will still think the originating transaction
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* is in progress, which leads to application-level inconsistency. The
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* upshot is that we gotta check TransactionIdIsInProgress first in all
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* code paths.
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*
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*
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* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/utils/time/tqual.c,v 1.49 2002/01/16 23:51:56 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/utils/time/tqual.c,v 1.49.2.1 2005/05/07 21:23:49 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -109,14 +123,16 @@ HeapTupleSatisfiesItself(HeapTupleHeader tuple)
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return false;
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}
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else if (!TransactionIdDidCommit(tuple->t_xmin))
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else if (TransactionIdIsInProgress(tuple->t_xmin))
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return false;
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else if (TransactionIdDidCommit(tuple->t_xmin))
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tuple->t_infomask |= HEAP_XMIN_COMMITTED;
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else
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{
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if (TransactionIdDidAbort(tuple->t_xmin))
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tuple->t_infomask |= HEAP_XMIN_INVALID; /* aborted */
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/* it must have aborted or crashed */
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tuple->t_infomask |= HEAP_XMIN_INVALID;
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return false;
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}
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else
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tuple->t_infomask |= HEAP_XMIN_COMMITTED;
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}
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/* by here, the inserting transaction has committed */
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@ -138,10 +154,13 @@ HeapTupleSatisfiesItself(HeapTupleHeader tuple)
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return false;
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}
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if (TransactionIdIsInProgress(tuple->t_xmax))
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return true;
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if (!TransactionIdDidCommit(tuple->t_xmax))
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{
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if (TransactionIdDidAbort(tuple->t_xmax))
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tuple->t_infomask |= HEAP_XMAX_INVALID; /* aborted */
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/* it must have aborted or crashed */
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tuple->t_infomask |= HEAP_XMAX_INVALID;
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return true;
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}
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@ -254,14 +273,16 @@ HeapTupleSatisfiesNow(HeapTupleHeader tuple)
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else
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return false; /* deleted before scan started */
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}
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else if (!TransactionIdDidCommit(tuple->t_xmin))
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else if (TransactionIdIsInProgress(tuple->t_xmin))
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return false;
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else if (TransactionIdDidCommit(tuple->t_xmin))
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tuple->t_infomask |= HEAP_XMIN_COMMITTED;
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else
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{
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if (TransactionIdDidAbort(tuple->t_xmin))
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tuple->t_infomask |= HEAP_XMIN_INVALID; /* aborted */
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/* it must have aborted or crashed */
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tuple->t_infomask |= HEAP_XMIN_INVALID;
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return false;
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}
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else
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tuple->t_infomask |= HEAP_XMIN_COMMITTED;
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}
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/* by here, the inserting transaction has committed */
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@ -286,10 +307,13 @@ HeapTupleSatisfiesNow(HeapTupleHeader tuple)
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return false; /* deleted before scan started */
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}
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if (TransactionIdIsInProgress(tuple->t_xmax))
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return true;
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if (!TransactionIdDidCommit(tuple->t_xmax))
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{
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if (TransactionIdDidAbort(tuple->t_xmax))
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tuple->t_infomask |= HEAP_XMAX_INVALID; /* aborted */
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/* it must have aborted or crashed */
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tuple->t_infomask |= HEAP_XMAX_INVALID;
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return true;
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}
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@ -428,14 +452,16 @@ HeapTupleSatisfiesUpdate(HeapTuple htuple)
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return HeapTupleInvisible; /* updated before scan
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* started */
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}
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else if (!TransactionIdDidCommit(tuple->t_xmin))
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else if (TransactionIdIsInProgress(tuple->t_xmin))
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return HeapTupleInvisible;
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else if (TransactionIdDidCommit(tuple->t_xmin))
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tuple->t_infomask |= HEAP_XMIN_COMMITTED;
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else
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{
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if (TransactionIdDidAbort(tuple->t_xmin))
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tuple->t_infomask |= HEAP_XMIN_INVALID; /* aborted */
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/* it must have aborted or crashed */
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tuple->t_infomask |= HEAP_XMIN_INVALID;
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return HeapTupleInvisible;
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}
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else
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tuple->t_infomask |= HEAP_XMIN_COMMITTED;
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}
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/* by here, the inserting transaction has committed */
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@ -461,15 +487,14 @@ HeapTupleSatisfiesUpdate(HeapTuple htuple)
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return HeapTupleInvisible; /* updated before scan started */
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}
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if (TransactionIdIsInProgress(tuple->t_xmax))
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return HeapTupleBeingUpdated;
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if (!TransactionIdDidCommit(tuple->t_xmax))
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{
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if (TransactionIdDidAbort(tuple->t_xmax))
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{
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tuple->t_infomask |= HEAP_XMAX_INVALID; /* aborted */
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return HeapTupleMayBeUpdated;
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}
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/* running xact */
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return HeapTupleBeingUpdated; /* in updation by other */
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/* it must have aborted or crashed */
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tuple->t_infomask |= HEAP_XMAX_INVALID;
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return HeapTupleMayBeUpdated;
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}
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/* xmax transaction committed */
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@ -553,19 +578,20 @@ HeapTupleSatisfiesDirty(HeapTupleHeader tuple)
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return false;
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}
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else if (!TransactionIdDidCommit(tuple->t_xmin))
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else if (TransactionIdIsInProgress(tuple->t_xmin))
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{
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if (TransactionIdDidAbort(tuple->t_xmin))
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{
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tuple->t_infomask |= HEAP_XMIN_INVALID;
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return false;
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}
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SnapshotDirty->xmin = tuple->t_xmin;
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/* XXX shouldn't we fall through to look at xmax? */
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return true; /* in insertion by other */
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}
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else
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else if (TransactionIdDidCommit(tuple->t_xmin))
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tuple->t_infomask |= HEAP_XMIN_COMMITTED;
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else
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{
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/* it must have aborted or crashed */
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tuple->t_infomask |= HEAP_XMIN_INVALID;
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return false;
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}
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}
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/* by here, the inserting transaction has committed */
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@ -588,16 +614,17 @@ HeapTupleSatisfiesDirty(HeapTupleHeader tuple)
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return false;
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}
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if (TransactionIdIsInProgress(tuple->t_xmax))
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{
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SnapshotDirty->xmax = tuple->t_xmax;
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return true;
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}
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if (!TransactionIdDidCommit(tuple->t_xmax))
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{
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if (TransactionIdDidAbort(tuple->t_xmax))
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{
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tuple->t_infomask |= HEAP_XMAX_INVALID; /* aborted */
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return true;
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}
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/* running xact */
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SnapshotDirty->xmax = tuple->t_xmax;
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return true; /* in updation by other */
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/* it must have aborted or crashed */
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tuple->t_infomask |= HEAP_XMAX_INVALID;
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return true;
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}
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/* xmax transaction committed */
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@ -693,14 +720,16 @@ HeapTupleSatisfiesSnapshot(HeapTupleHeader tuple, Snapshot snapshot)
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else
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return false; /* deleted before scan started */
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}
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else if (!TransactionIdDidCommit(tuple->t_xmin))
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else if (TransactionIdIsInProgress(tuple->t_xmin))
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return false;
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else if (TransactionIdDidCommit(tuple->t_xmin))
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tuple->t_infomask |= HEAP_XMIN_COMMITTED;
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else
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{
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if (TransactionIdDidAbort(tuple->t_xmin))
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tuple->t_infomask |= HEAP_XMIN_INVALID;
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/* it must have aborted or crashed */
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tuple->t_infomask |= HEAP_XMIN_INVALID;
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return false;
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}
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else
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tuple->t_infomask |= HEAP_XMIN_COMMITTED;
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}
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/*
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@ -737,10 +766,13 @@ HeapTupleSatisfiesSnapshot(HeapTupleHeader tuple, Snapshot snapshot)
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return false; /* deleted before scan started */
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}
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if (TransactionIdIsInProgress(tuple->t_xmax))
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return true;
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if (!TransactionIdDidCommit(tuple->t_xmax))
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{
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if (TransactionIdDidAbort(tuple->t_xmax))
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tuple->t_infomask |= HEAP_XMAX_INVALID; /* aborted */
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/* it must have aborted or crashed */
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tuple->t_infomask |= HEAP_XMAX_INVALID;
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return true;
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}
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@ -785,13 +817,6 @@ HeapTupleSatisfiesVacuum(HeapTupleHeader tuple, TransactionId OldestXmin)
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*
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* If the inserting transaction aborted, then the tuple was never visible
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* to any other transaction, so we can delete it immediately.
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*
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* NOTE: must check TransactionIdIsInProgress (which looks in PROC array)
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* before TransactionIdDidCommit/TransactionIdDidAbort (which look in
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* pg_clog). Otherwise we have a race condition where we might decide
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* that a just-committed transaction crashed, because none of the
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* tests succeed. xact.c is careful to record commit/abort in pg_clog
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* before it unsets MyProc->xid in PROC array.
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*/
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if (!(tuple->t_infomask & HEAP_XMIN_COMMITTED))
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{
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@ -828,17 +853,9 @@ HeapTupleSatisfiesVacuum(HeapTupleHeader tuple, TransactionId OldestXmin)
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return HEAPTUPLE_INSERT_IN_PROGRESS;
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else if (TransactionIdDidCommit(tuple->t_xmin))
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tuple->t_infomask |= HEAP_XMIN_COMMITTED;
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else if (TransactionIdDidAbort(tuple->t_xmin))
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{
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tuple->t_infomask |= HEAP_XMIN_INVALID;
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return HEAPTUPLE_DEAD;
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}
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else
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{
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/*
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* Not in Progress, Not Committed, Not Aborted - so it's from
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* crashed process. - vadim 11/26/96
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*/
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/* it must be aborted or crashed */
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tuple->t_infomask |= HEAP_XMIN_INVALID;
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return HEAPTUPLE_DEAD;
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}
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@ -879,22 +896,12 @@ HeapTupleSatisfiesVacuum(HeapTupleHeader tuple, TransactionId OldestXmin)
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return HEAPTUPLE_DELETE_IN_PROGRESS;
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else if (TransactionIdDidCommit(tuple->t_xmax))
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tuple->t_infomask |= HEAP_XMAX_COMMITTED;
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else if (TransactionIdDidAbort(tuple->t_xmax))
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{
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tuple->t_infomask |= HEAP_XMAX_INVALID;
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return HEAPTUPLE_LIVE;
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}
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else
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{
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/*
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* Not in Progress, Not Committed, Not Aborted - so it's from
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* crashed process. - vadim 06/02/97
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*/
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/* it must be aborted or crashed */
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tuple->t_infomask |= HEAP_XMAX_INVALID;
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return HEAPTUPLE_LIVE;
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}
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/* Should only get here if we set XMAX_COMMITTED */
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Assert(tuple->t_infomask & HEAP_XMAX_COMMITTED);
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}
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/*
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