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9ffc8ed58b
http://archives.postgresql.org/pgsql-hackers/2004-10/msg00464.php. This fix is intended to be permanent: it moves the responsibility for calling SetBufferCommitInfoNeedsSave() into the tqual.c routines, eliminating the requirement for callers to test whether t_infomask changed. Also, tighten validity checking on buffer IDs in bufmgr.c --- several routines were paranoid about out-of-range shared buffer numbers but not about out-of-range local ones, which seems a tad pointless.
1251 lines
35 KiB
C
1251 lines
35 KiB
C
/*-------------------------------------------------------------------------
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*
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* tqual.c
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* POSTGRES "time" qualification code, ie, tuple visibility rules.
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*
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* The caller must hold at least a shared buffer context lock on the buffer
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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: all the HeapTupleSatisfies routines will update the tuple's
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* "hint" status bits if we see that the inserting or deleting transaction
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* has now committed or aborted.
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*
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*
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* Portions Copyright (c) 1996-2004, 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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* $PostgreSQL: pgsql/src/backend/utils/time/tqual.c,v 1.80 2004/10/15 22:40:16 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "access/subtrans.h"
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#include "storage/sinval.h"
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#include "utils/tqual.h"
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/*
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* These SnapshotData structs are static to simplify memory allocation
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* (see the hack in GetSnapshotData to avoid repeated malloc/free).
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*/
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static SnapshotData SnapshotDirtyData;
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static SnapshotData SerializableSnapshotData;
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static SnapshotData LatestSnapshotData;
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/* Externally visible pointers to valid snapshots: */
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Snapshot SnapshotDirty = &SnapshotDirtyData;
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Snapshot SerializableSnapshot = NULL;
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Snapshot LatestSnapshot = NULL;
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/*
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* This pointer is not maintained by this module, but it's convenient
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* to declare it here anyway. Callers typically assign a copy of
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* GetTransactionSnapshot's result to ActiveSnapshot.
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*/
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Snapshot ActiveSnapshot = NULL;
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/* These are updated by GetSnapshotData: */
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TransactionId TransactionXmin = InvalidTransactionId;
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TransactionId RecentXmin = InvalidTransactionId;
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TransactionId RecentGlobalXmin = InvalidTransactionId;
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/*
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* HeapTupleSatisfiesItself
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* True iff heap tuple is valid "for itself".
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*
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* Here, we consider the effects of:
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* all committed transactions (as of the current instant)
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* previous commands of this transaction
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* changes made by the current command
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*
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* Note:
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* Assumes heap tuple is valid.
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*
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* The satisfaction of "itself" requires the following:
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*
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* ((Xmin == my-transaction && the row was updated by the current transaction, and
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* (Xmax is null it was not deleted
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* [|| Xmax != my-transaction)]) [or it was deleted by another transaction]
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* ||
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*
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* (Xmin is committed && the row was modified by a committed transaction, and
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* (Xmax is null || the row has not been deleted, or
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* (Xmax != my-transaction && the row was deleted by another transaction
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* Xmax is not committed))) that has not been committed
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*/
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bool
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HeapTupleSatisfiesItself(HeapTupleHeader tuple, Buffer buffer)
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{
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if (!(tuple->t_infomask & HEAP_XMIN_COMMITTED))
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{
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if (tuple->t_infomask & HEAP_XMIN_INVALID)
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return false;
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if (tuple->t_infomask & HEAP_MOVED_OFF)
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{
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TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
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if (TransactionIdIsCurrentTransactionId(xvac))
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return false;
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if (!TransactionIdIsInProgress(xvac))
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{
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if (TransactionIdDidCommit(xvac))
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{
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tuple->t_infomask |= HEAP_XMIN_INVALID;
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SetBufferCommitInfoNeedsSave(buffer);
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return false;
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}
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tuple->t_infomask |= HEAP_XMIN_COMMITTED;
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SetBufferCommitInfoNeedsSave(buffer);
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}
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}
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else if (tuple->t_infomask & HEAP_MOVED_IN)
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{
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TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
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if (!TransactionIdIsCurrentTransactionId(xvac))
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{
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if (TransactionIdIsInProgress(xvac))
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return false;
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if (TransactionIdDidCommit(xvac))
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{
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tuple->t_infomask |= HEAP_XMIN_COMMITTED;
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SetBufferCommitInfoNeedsSave(buffer);
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}
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else
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{
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tuple->t_infomask |= HEAP_XMIN_INVALID;
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SetBufferCommitInfoNeedsSave(buffer);
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return false;
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}
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}
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}
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else if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(tuple)))
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{
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if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid */
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return true;
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/* deleting subtransaction aborted */
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if (TransactionIdDidAbort(HeapTupleHeaderGetXmax(tuple)))
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{
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tuple->t_infomask |= HEAP_XMAX_INVALID;
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SetBufferCommitInfoNeedsSave(buffer);
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return true;
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}
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Assert(TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)));
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if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
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return true;
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return false;
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}
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else if (!TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
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{
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if (TransactionIdDidAbort(HeapTupleHeaderGetXmin(tuple)))
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{
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tuple->t_infomask |= HEAP_XMIN_INVALID;
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SetBufferCommitInfoNeedsSave(buffer);
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}
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return false;
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}
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else
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{
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tuple->t_infomask |= HEAP_XMIN_COMMITTED;
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SetBufferCommitInfoNeedsSave(buffer);
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}
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}
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/* by here, the inserting transaction has committed */
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if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid or aborted */
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return true;
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if (tuple->t_infomask & HEAP_XMAX_COMMITTED)
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{
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if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
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return true;
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return false; /* updated by other */
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}
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if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)))
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{
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if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
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return true;
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return false;
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}
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if (!TransactionIdDidCommit(HeapTupleHeaderGetXmax(tuple)))
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{
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if (TransactionIdDidAbort(HeapTupleHeaderGetXmax(tuple)))
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{
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tuple->t_infomask |= HEAP_XMAX_INVALID;
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SetBufferCommitInfoNeedsSave(buffer);
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}
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return true;
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}
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/* xmax transaction committed */
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if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
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{
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tuple->t_infomask |= HEAP_XMAX_INVALID;
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SetBufferCommitInfoNeedsSave(buffer);
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return true;
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}
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tuple->t_infomask |= HEAP_XMAX_COMMITTED;
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SetBufferCommitInfoNeedsSave(buffer);
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return false;
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}
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/*
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* HeapTupleSatisfiesNow
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* True iff heap tuple is valid "now".
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*
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* Here, we consider the effects of:
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* all committed transactions (as of the current instant)
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* previous commands of this transaction
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*
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* Note we do _not_ include changes made by the current command. This
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* solves the "Halloween problem" wherein an UPDATE might try to re-update
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* its own output tuples.
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*
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* Note:
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* Assumes heap tuple is valid.
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*
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* The satisfaction of "now" requires the following:
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*
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* ((Xmin == my-transaction && changed by the current transaction
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* Cmin != my-command && but not by this command, and
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* (Xmax is null || the row has not been deleted, or
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* (Xmax == my-transaction && it was deleted by the current transaction
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* Cmax != my-command))) but not by this command,
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* || or
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*
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* (Xmin is committed && the row was modified by a committed transaction, and
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* (Xmax is null || the row has not been deleted, or
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* (Xmax == my-transaction && the row is being deleted by this command, or
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* Cmax == my-command) ||
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* (Xmax is not committed && the row was deleted by another transaction
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* Xmax != my-transaction)))) that has not been committed
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*
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* mao says 17 march 1993: the tests in this routine are correct;
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* if you think they're not, you're wrong, and you should think
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* about it again. i know, it happened to me. we don't need to
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* check commit time against the start time of this transaction
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* because 2ph locking protects us from doing the wrong thing.
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* if you mess around here, you'll break serializability. the only
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* problem with this code is that it does the wrong thing for system
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* catalog updates, because the catalogs aren't subject to 2ph, so
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* the serializability guarantees we provide don't extend to xacts
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* that do catalog accesses. this is unfortunate, but not critical.
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*/
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bool
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HeapTupleSatisfiesNow(HeapTupleHeader tuple, Buffer buffer)
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{
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if (!(tuple->t_infomask & HEAP_XMIN_COMMITTED))
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{
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if (tuple->t_infomask & HEAP_XMIN_INVALID)
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return false;
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if (tuple->t_infomask & HEAP_MOVED_OFF)
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{
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TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
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if (TransactionIdIsCurrentTransactionId(xvac))
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return false;
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if (!TransactionIdIsInProgress(xvac))
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{
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if (TransactionIdDidCommit(xvac))
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{
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tuple->t_infomask |= HEAP_XMIN_INVALID;
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SetBufferCommitInfoNeedsSave(buffer);
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return false;
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}
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tuple->t_infomask |= HEAP_XMIN_COMMITTED;
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SetBufferCommitInfoNeedsSave(buffer);
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}
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}
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else if (tuple->t_infomask & HEAP_MOVED_IN)
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{
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TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
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if (!TransactionIdIsCurrentTransactionId(xvac))
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{
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if (TransactionIdIsInProgress(xvac))
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return false;
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if (TransactionIdDidCommit(xvac))
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{
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tuple->t_infomask |= HEAP_XMIN_COMMITTED;
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SetBufferCommitInfoNeedsSave(buffer);
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}
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else
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{
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tuple->t_infomask |= HEAP_XMIN_INVALID;
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SetBufferCommitInfoNeedsSave(buffer);
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return false;
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}
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}
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}
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else if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(tuple)))
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{
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if (HeapTupleHeaderGetCmin(tuple) >= GetCurrentCommandId())
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return false; /* inserted after scan started */
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if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid */
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return true;
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/* deleting subtransaction aborted */
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if (TransactionIdDidAbort(HeapTupleHeaderGetXmax(tuple)))
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{
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tuple->t_infomask |= HEAP_XMAX_INVALID;
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SetBufferCommitInfoNeedsSave(buffer);
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return true;
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}
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Assert(TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)));
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if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
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return true;
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if (HeapTupleHeaderGetCmax(tuple) >= GetCurrentCommandId())
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return true; /* deleted after scan started */
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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(HeapTupleHeaderGetXmin(tuple)))
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{
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if (TransactionIdDidAbort(HeapTupleHeaderGetXmin(tuple)))
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{
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tuple->t_infomask |= HEAP_XMIN_INVALID;
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SetBufferCommitInfoNeedsSave(buffer);
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}
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return false;
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}
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else
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{
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tuple->t_infomask |= HEAP_XMIN_COMMITTED;
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SetBufferCommitInfoNeedsSave(buffer);
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}
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}
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/* by here, the inserting transaction has committed */
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if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid or aborted */
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return true;
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if (tuple->t_infomask & HEAP_XMAX_COMMITTED)
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{
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if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
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return true;
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return false;
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}
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if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)))
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{
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if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
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return true;
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if (HeapTupleHeaderGetCmax(tuple) >= GetCurrentCommandId())
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return true; /* deleted after scan started */
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else
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return false; /* deleted before scan started */
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}
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if (!TransactionIdDidCommit(HeapTupleHeaderGetXmax(tuple)))
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{
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if (TransactionIdDidAbort(HeapTupleHeaderGetXmax(tuple)))
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{
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tuple->t_infomask |= HEAP_XMAX_INVALID;
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SetBufferCommitInfoNeedsSave(buffer);
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}
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return true;
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}
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/* xmax transaction committed */
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if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
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{
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tuple->t_infomask |= HEAP_XMAX_INVALID;
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SetBufferCommitInfoNeedsSave(buffer);
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return true;
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}
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tuple->t_infomask |= HEAP_XMAX_COMMITTED;
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SetBufferCommitInfoNeedsSave(buffer);
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return false;
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}
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/*
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* HeapTupleSatisfiesToast
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* True iff heap tuple is valid as a TOAST row.
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*
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* This is a simplified version that only checks for VACUUM moving conditions.
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* It's appropriate for TOAST usage because TOAST really doesn't want to do
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* its own time qual checks; if you can see the main table row that contains
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* a TOAST reference, you should be able to see the TOASTed value. However,
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* vacuuming a TOAST table is independent of the main table, and in case such
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* a vacuum fails partway through, we'd better do this much checking.
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*
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* Among other things, this means you can't do UPDATEs of rows in a TOAST
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* table.
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*/
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bool
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HeapTupleSatisfiesToast(HeapTupleHeader tuple, Buffer buffer)
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{
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if (!(tuple->t_infomask & HEAP_XMIN_COMMITTED))
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{
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if (tuple->t_infomask & HEAP_XMIN_INVALID)
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return false;
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if (tuple->t_infomask & HEAP_MOVED_OFF)
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{
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TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
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if (TransactionIdIsCurrentTransactionId(xvac))
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return false;
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if (!TransactionIdIsInProgress(xvac))
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{
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if (TransactionIdDidCommit(xvac))
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{
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tuple->t_infomask |= HEAP_XMIN_INVALID;
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SetBufferCommitInfoNeedsSave(buffer);
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return false;
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}
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tuple->t_infomask |= HEAP_XMIN_COMMITTED;
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SetBufferCommitInfoNeedsSave(buffer);
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}
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}
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else if (tuple->t_infomask & HEAP_MOVED_IN)
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{
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TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
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if (!TransactionIdIsCurrentTransactionId(xvac))
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{
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if (TransactionIdIsInProgress(xvac))
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return false;
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if (TransactionIdDidCommit(xvac))
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{
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tuple->t_infomask |= HEAP_XMIN_COMMITTED;
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SetBufferCommitInfoNeedsSave(buffer);
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}
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else
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{
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tuple->t_infomask |= HEAP_XMIN_INVALID;
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SetBufferCommitInfoNeedsSave(buffer);
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return false;
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}
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}
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}
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}
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/* otherwise assume the tuple is valid for TOAST. */
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return true;
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}
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|
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/*
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* HeapTupleSatisfiesUpdate
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*
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* Same logic as HeapTupleSatisfiesNow, but returns a more detailed result
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* code, since UPDATE needs to know more than "is it visible?". Also,
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* tuples of my own xact are tested against the passed CommandId not
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* CurrentCommandId.
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*/
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int
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HeapTupleSatisfiesUpdate(HeapTupleHeader tuple, CommandId curcid,
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Buffer buffer)
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{
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if (!(tuple->t_infomask & HEAP_XMIN_COMMITTED))
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{
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if (tuple->t_infomask & HEAP_XMIN_INVALID)
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return HeapTupleInvisible;
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|
|
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if (tuple->t_infomask & HEAP_MOVED_OFF)
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{
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|
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
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|
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if (TransactionIdIsCurrentTransactionId(xvac))
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return HeapTupleInvisible;
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if (!TransactionIdIsInProgress(xvac))
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|
{
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if (TransactionIdDidCommit(xvac))
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|
{
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tuple->t_infomask |= HEAP_XMIN_INVALID;
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SetBufferCommitInfoNeedsSave(buffer);
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return HeapTupleInvisible;
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}
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tuple->t_infomask |= HEAP_XMIN_COMMITTED;
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SetBufferCommitInfoNeedsSave(buffer);
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|
}
|
|
}
|
|
else if (tuple->t_infomask & HEAP_MOVED_IN)
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|
{
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|
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
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|
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if (!TransactionIdIsCurrentTransactionId(xvac))
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{
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if (TransactionIdIsInProgress(xvac))
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return HeapTupleInvisible;
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if (TransactionIdDidCommit(xvac))
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|
{
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tuple->t_infomask |= HEAP_XMIN_COMMITTED;
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SetBufferCommitInfoNeedsSave(buffer);
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|
}
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else
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{
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tuple->t_infomask |= HEAP_XMIN_INVALID;
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SetBufferCommitInfoNeedsSave(buffer);
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return HeapTupleInvisible;
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}
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}
|
|
}
|
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else if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(tuple)))
|
|
{
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if (HeapTupleHeaderGetCmin(tuple) >= curcid)
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return HeapTupleInvisible; /* inserted after scan
|
|
* started */
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|
if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid */
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|
return HeapTupleMayBeUpdated;
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|
|
/* deleting subtransaction aborted */
|
|
if (TransactionIdDidAbort(HeapTupleHeaderGetXmax(tuple)))
|
|
{
|
|
tuple->t_infomask |= HEAP_XMAX_INVALID;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
return HeapTupleMayBeUpdated;
|
|
}
|
|
|
|
Assert(TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)));
|
|
|
|
if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
|
|
return HeapTupleMayBeUpdated;
|
|
|
|
if (HeapTupleHeaderGetCmax(tuple) >= curcid)
|
|
return HeapTupleSelfUpdated; /* updated after scan
|
|
* started */
|
|
else
|
|
return HeapTupleInvisible; /* updated before scan
|
|
* started */
|
|
}
|
|
else if (!TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
|
|
{
|
|
if (TransactionIdDidAbort(HeapTupleHeaderGetXmin(tuple)))
|
|
{
|
|
tuple->t_infomask |= HEAP_XMIN_INVALID;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
}
|
|
return HeapTupleInvisible;
|
|
}
|
|
else
|
|
{
|
|
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
}
|
|
}
|
|
|
|
/* by here, the inserting transaction has committed */
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid or aborted */
|
|
return HeapTupleMayBeUpdated;
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_COMMITTED)
|
|
{
|
|
if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
|
|
return HeapTupleMayBeUpdated;
|
|
return HeapTupleUpdated; /* updated by other */
|
|
}
|
|
|
|
if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)))
|
|
{
|
|
if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
|
|
return HeapTupleMayBeUpdated;
|
|
if (HeapTupleHeaderGetCmax(tuple) >= curcid)
|
|
return HeapTupleSelfUpdated; /* updated after scan
|
|
* started */
|
|
else
|
|
return HeapTupleInvisible; /* updated before scan started */
|
|
}
|
|
|
|
if (!TransactionIdDidCommit(HeapTupleHeaderGetXmax(tuple)))
|
|
{
|
|
if (TransactionIdDidAbort(HeapTupleHeaderGetXmax(tuple)))
|
|
{
|
|
tuple->t_infomask |= HEAP_XMAX_INVALID;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
return HeapTupleMayBeUpdated;
|
|
}
|
|
/* running xact */
|
|
return HeapTupleBeingUpdated; /* in updation by other */
|
|
}
|
|
|
|
/* xmax transaction committed */
|
|
|
|
if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
|
|
{
|
|
tuple->t_infomask |= HEAP_XMAX_INVALID;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
return HeapTupleMayBeUpdated;
|
|
}
|
|
|
|
tuple->t_infomask |= HEAP_XMAX_COMMITTED;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
return HeapTupleUpdated; /* updated by other */
|
|
}
|
|
|
|
/*
|
|
* HeapTupleSatisfiesDirty
|
|
* True iff heap tuple is valid including effects of open transactions.
|
|
*
|
|
* Here, we consider the effects of:
|
|
* all committed and in-progress transactions (as of the current instant)
|
|
* previous commands of this transaction
|
|
* changes made by the current command
|
|
*
|
|
* This is essentially like HeapTupleSatisfiesItself as far as effects of
|
|
* the current transaction and committed/aborted xacts are concerned.
|
|
* However, we also include the effects of other xacts still in progress.
|
|
*
|
|
* Returns extra information in the global variable SnapshotDirty, namely
|
|
* xids of concurrent xacts that affected the tuple. Also, the tuple's
|
|
* t_ctid (forward link) is returned if it's being updated.
|
|
*/
|
|
bool
|
|
HeapTupleSatisfiesDirty(HeapTupleHeader tuple, Buffer buffer)
|
|
{
|
|
SnapshotDirty->xmin = SnapshotDirty->xmax = InvalidTransactionId;
|
|
ItemPointerSetInvalid(&(SnapshotDirty->tid));
|
|
|
|
if (!(tuple->t_infomask & HEAP_XMIN_COMMITTED))
|
|
{
|
|
if (tuple->t_infomask & HEAP_XMIN_INVALID)
|
|
return false;
|
|
|
|
if (tuple->t_infomask & HEAP_MOVED_OFF)
|
|
{
|
|
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
|
|
|
|
if (TransactionIdIsCurrentTransactionId(xvac))
|
|
return false;
|
|
if (!TransactionIdIsInProgress(xvac))
|
|
{
|
|
if (TransactionIdDidCommit(xvac))
|
|
{
|
|
tuple->t_infomask |= HEAP_XMIN_INVALID;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
return false;
|
|
}
|
|
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
}
|
|
}
|
|
else if (tuple->t_infomask & HEAP_MOVED_IN)
|
|
{
|
|
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
|
|
|
|
if (!TransactionIdIsCurrentTransactionId(xvac))
|
|
{
|
|
if (TransactionIdIsInProgress(xvac))
|
|
return false;
|
|
if (TransactionIdDidCommit(xvac))
|
|
{
|
|
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
}
|
|
else
|
|
{
|
|
tuple->t_infomask |= HEAP_XMIN_INVALID;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
return false;
|
|
}
|
|
}
|
|
}
|
|
else if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(tuple)))
|
|
{
|
|
if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid */
|
|
return true;
|
|
|
|
/* deleting subtransaction aborted */
|
|
if (TransactionIdDidAbort(HeapTupleHeaderGetXmax(tuple)))
|
|
{
|
|
tuple->t_infomask |= HEAP_XMAX_INVALID;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
return true;
|
|
}
|
|
|
|
Assert(TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)));
|
|
|
|
if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
else if (!TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
|
|
{
|
|
if (TransactionIdDidAbort(HeapTupleHeaderGetXmin(tuple)))
|
|
{
|
|
tuple->t_infomask |= HEAP_XMIN_INVALID;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
return false;
|
|
}
|
|
SnapshotDirty->xmin = HeapTupleHeaderGetXmin(tuple);
|
|
/* XXX shouldn't we fall through to look at xmax? */
|
|
return true; /* in insertion by other */
|
|
}
|
|
else
|
|
{
|
|
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
}
|
|
}
|
|
|
|
/* by here, the inserting transaction has committed */
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid or aborted */
|
|
return true;
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_COMMITTED)
|
|
{
|
|
if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
|
|
return true;
|
|
SnapshotDirty->tid = tuple->t_ctid;
|
|
return false; /* updated by other */
|
|
}
|
|
|
|
if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)))
|
|
{
|
|
if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
if (!TransactionIdDidCommit(HeapTupleHeaderGetXmax(tuple)))
|
|
{
|
|
if (TransactionIdDidAbort(HeapTupleHeaderGetXmax(tuple)))
|
|
{
|
|
tuple->t_infomask |= HEAP_XMAX_INVALID;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
return true;
|
|
}
|
|
/* running xact */
|
|
SnapshotDirty->xmax = HeapTupleHeaderGetXmax(tuple);
|
|
return true; /* in updation by other */
|
|
}
|
|
|
|
/* xmax transaction committed */
|
|
|
|
if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
|
|
{
|
|
tuple->t_infomask |= HEAP_XMAX_INVALID;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
return true;
|
|
}
|
|
|
|
tuple->t_infomask |= HEAP_XMAX_COMMITTED;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
SnapshotDirty->tid = tuple->t_ctid;
|
|
return false; /* updated by other */
|
|
}
|
|
|
|
/*
|
|
* HeapTupleSatisfiesSnapshot
|
|
* True iff heap tuple is valid for the given snapshot.
|
|
*
|
|
* Here, we consider the effects of:
|
|
* all transactions committed as of the time of the given snapshot
|
|
* previous commands of this transaction
|
|
*
|
|
* Does _not_ include:
|
|
* transactions shown as in-progress by the snapshot
|
|
* transactions started after the snapshot was taken
|
|
* changes made by the current command
|
|
*
|
|
* This is the same as HeapTupleSatisfiesNow, except that transactions that
|
|
* were in progress or as yet unstarted when the snapshot was taken will
|
|
* be treated as uncommitted, even if they have committed by now.
|
|
*
|
|
* (Notice, however, that the tuple status hint bits will be updated on the
|
|
* basis of the true state of the transaction, even if we then pretend we
|
|
* can't see it.)
|
|
*/
|
|
bool
|
|
HeapTupleSatisfiesSnapshot(HeapTupleHeader tuple, Snapshot snapshot,
|
|
Buffer buffer)
|
|
{
|
|
if (!(tuple->t_infomask & HEAP_XMIN_COMMITTED))
|
|
{
|
|
if (tuple->t_infomask & HEAP_XMIN_INVALID)
|
|
return false;
|
|
|
|
if (tuple->t_infomask & HEAP_MOVED_OFF)
|
|
{
|
|
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
|
|
|
|
if (TransactionIdIsCurrentTransactionId(xvac))
|
|
return false;
|
|
if (!TransactionIdIsInProgress(xvac))
|
|
{
|
|
if (TransactionIdDidCommit(xvac))
|
|
{
|
|
tuple->t_infomask |= HEAP_XMIN_INVALID;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
return false;
|
|
}
|
|
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
}
|
|
}
|
|
else if (tuple->t_infomask & HEAP_MOVED_IN)
|
|
{
|
|
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
|
|
|
|
if (!TransactionIdIsCurrentTransactionId(xvac))
|
|
{
|
|
if (TransactionIdIsInProgress(xvac))
|
|
return false;
|
|
if (TransactionIdDidCommit(xvac))
|
|
{
|
|
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
}
|
|
else
|
|
{
|
|
tuple->t_infomask |= HEAP_XMIN_INVALID;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
return false;
|
|
}
|
|
}
|
|
}
|
|
else if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(tuple)))
|
|
{
|
|
if (HeapTupleHeaderGetCmin(tuple) >= snapshot->curcid)
|
|
return false; /* inserted after scan started */
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid */
|
|
return true;
|
|
|
|
/* deleting subtransaction aborted */
|
|
/* FIXME -- is this correct w.r.t. the cmax of the tuple? */
|
|
if (TransactionIdDidAbort(HeapTupleHeaderGetXmax(tuple)))
|
|
{
|
|
tuple->t_infomask |= HEAP_XMAX_INVALID;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
return true;
|
|
}
|
|
|
|
Assert(TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)));
|
|
|
|
if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
|
|
return true;
|
|
|
|
if (HeapTupleHeaderGetCmax(tuple) >= snapshot->curcid)
|
|
return true; /* deleted after scan started */
|
|
else
|
|
return false; /* deleted before scan started */
|
|
}
|
|
else if (!TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
|
|
{
|
|
if (TransactionIdDidAbort(HeapTupleHeaderGetXmin(tuple)))
|
|
{
|
|
tuple->t_infomask |= HEAP_XMIN_INVALID;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
}
|
|
return false;
|
|
}
|
|
else
|
|
{
|
|
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* By here, the inserting transaction has committed - have to check
|
|
* when...
|
|
*
|
|
* Note that the provided snapshot contains only top-level XIDs, so we
|
|
* have to convert a subxact XID to its parent for comparison.
|
|
* However, we can make first-pass range checks with the given XID,
|
|
* because a subxact with XID < xmin has surely also got a parent with
|
|
* XID < xmin, while one with XID >= xmax must belong to a parent that
|
|
* was not yet committed at the time of this snapshot.
|
|
*/
|
|
if (TransactionIdFollowsOrEquals(HeapTupleHeaderGetXmin(tuple),
|
|
snapshot->xmin))
|
|
{
|
|
TransactionId parentXid;
|
|
|
|
if (TransactionIdFollowsOrEquals(HeapTupleHeaderGetXmin(tuple),
|
|
snapshot->xmax))
|
|
return false;
|
|
|
|
parentXid = SubTransGetTopmostTransaction(HeapTupleHeaderGetXmin(tuple));
|
|
|
|
if (TransactionIdFollowsOrEquals(parentXid, snapshot->xmin))
|
|
{
|
|
uint32 i;
|
|
|
|
/* no point in checking parentXid against xmax here */
|
|
|
|
for (i = 0; i < snapshot->xcnt; i++)
|
|
{
|
|
if (TransactionIdEquals(parentXid, snapshot->xip[i]))
|
|
return false;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid or aborted */
|
|
return true;
|
|
|
|
if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
|
|
return true;
|
|
|
|
if (!(tuple->t_infomask & HEAP_XMAX_COMMITTED))
|
|
{
|
|
if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)))
|
|
{
|
|
if (HeapTupleHeaderGetCmax(tuple) >= snapshot->curcid)
|
|
return true; /* deleted after scan started */
|
|
else
|
|
return false; /* deleted before scan started */
|
|
}
|
|
|
|
if (!TransactionIdDidCommit(HeapTupleHeaderGetXmax(tuple)))
|
|
{
|
|
if (TransactionIdDidAbort(HeapTupleHeaderGetXmax(tuple)))
|
|
{
|
|
tuple->t_infomask |= HEAP_XMAX_INVALID;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/* xmax transaction committed */
|
|
tuple->t_infomask |= HEAP_XMAX_COMMITTED;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
}
|
|
|
|
/*
|
|
* OK, the deleting transaction committed too ... but when?
|
|
*
|
|
* See notes for the similar tests on tuple xmin, above.
|
|
*/
|
|
if (TransactionIdFollowsOrEquals(HeapTupleHeaderGetXmax(tuple),
|
|
snapshot->xmin))
|
|
{
|
|
TransactionId parentXid;
|
|
|
|
if (TransactionIdFollowsOrEquals(HeapTupleHeaderGetXmax(tuple),
|
|
snapshot->xmax))
|
|
return true;
|
|
|
|
parentXid = SubTransGetTopmostTransaction(HeapTupleHeaderGetXmax(tuple));
|
|
|
|
if (TransactionIdFollowsOrEquals(parentXid, snapshot->xmin))
|
|
{
|
|
uint32 i;
|
|
|
|
/* no point in checking parentXid against xmax here */
|
|
|
|
for (i = 0; i < snapshot->xcnt; i++)
|
|
{
|
|
if (TransactionIdEquals(parentXid, snapshot->xip[i]))
|
|
return true;
|
|
}
|
|
}
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
|
|
/*
|
|
* HeapTupleSatisfiesVacuum
|
|
*
|
|
* Determine the status of tuples for VACUUM purposes. Here, what
|
|
* we mainly want to know is if a tuple is potentially visible to *any*
|
|
* running transaction. If so, it can't be removed yet by VACUUM.
|
|
*
|
|
* OldestXmin is a cutoff XID (obtained from GetOldestXmin()). Tuples
|
|
* deleted by XIDs >= OldestXmin are deemed "recently dead"; they might
|
|
* still be visible to some open transaction, so we can't remove them,
|
|
* even if we see that the deleting transaction has committed.
|
|
*/
|
|
HTSV_Result
|
|
HeapTupleSatisfiesVacuum(HeapTupleHeader tuple, TransactionId OldestXmin,
|
|
Buffer buffer)
|
|
{
|
|
/*
|
|
* Has inserting transaction committed?
|
|
*
|
|
* 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))
|
|
{
|
|
if (tuple->t_infomask & HEAP_XMIN_INVALID)
|
|
return HEAPTUPLE_DEAD;
|
|
else if (tuple->t_infomask & HEAP_MOVED_OFF)
|
|
{
|
|
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
|
|
|
|
if (TransactionIdIsCurrentTransactionId(xvac))
|
|
return HEAPTUPLE_DELETE_IN_PROGRESS;
|
|
if (TransactionIdIsInProgress(xvac))
|
|
return HEAPTUPLE_DELETE_IN_PROGRESS;
|
|
if (TransactionIdDidCommit(xvac))
|
|
{
|
|
tuple->t_infomask |= HEAP_XMIN_INVALID;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
return HEAPTUPLE_DEAD;
|
|
}
|
|
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
}
|
|
else if (tuple->t_infomask & HEAP_MOVED_IN)
|
|
{
|
|
TransactionId xvac = HeapTupleHeaderGetXvac(tuple);
|
|
|
|
if (TransactionIdIsCurrentTransactionId(xvac))
|
|
return HEAPTUPLE_INSERT_IN_PROGRESS;
|
|
if (TransactionIdIsInProgress(xvac))
|
|
return HEAPTUPLE_INSERT_IN_PROGRESS;
|
|
if (TransactionIdDidCommit(xvac))
|
|
{
|
|
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
}
|
|
else
|
|
{
|
|
tuple->t_infomask |= HEAP_XMIN_INVALID;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
return HEAPTUPLE_DEAD;
|
|
}
|
|
}
|
|
else if (TransactionIdIsInProgress(HeapTupleHeaderGetXmin(tuple)))
|
|
{
|
|
if (tuple->t_infomask & HEAP_XMAX_INVALID) /* xid invalid */
|
|
return HEAPTUPLE_INSERT_IN_PROGRESS;
|
|
if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
|
|
return HEAPTUPLE_INSERT_IN_PROGRESS;
|
|
/* inserted and then deleted by same xact */
|
|
return HEAPTUPLE_DELETE_IN_PROGRESS;
|
|
}
|
|
else if (TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
|
|
{
|
|
tuple->t_infomask |= HEAP_XMIN_COMMITTED;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
}
|
|
else
|
|
{
|
|
/*
|
|
* Not in Progress, Not Committed, so either Aborted or
|
|
* crashed
|
|
*/
|
|
tuple->t_infomask |= HEAP_XMIN_INVALID;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
return HEAPTUPLE_DEAD;
|
|
}
|
|
/* Should only get here if we set XMIN_COMMITTED */
|
|
Assert(tuple->t_infomask & HEAP_XMIN_COMMITTED);
|
|
}
|
|
|
|
/*
|
|
* Okay, the inserter committed, so it was good at some point. Now
|
|
* what about the deleting transaction?
|
|
*/
|
|
if (tuple->t_infomask & HEAP_XMAX_INVALID)
|
|
return HEAPTUPLE_LIVE;
|
|
|
|
if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
|
|
{
|
|
/*
|
|
* "Deleting" xact really only marked it for update, so the tuple
|
|
* is live in any case. However, we must make sure that either
|
|
* XMAX_COMMITTED or XMAX_INVALID gets set once the xact is gone;
|
|
* otherwise it is unsafe to recycle CLOG status after vacuuming.
|
|
*/
|
|
if (!(tuple->t_infomask & HEAP_XMAX_COMMITTED))
|
|
{
|
|
if (TransactionIdIsInProgress(HeapTupleHeaderGetXmax(tuple)))
|
|
return HEAPTUPLE_LIVE;
|
|
|
|
/*
|
|
* We don't really care whether xmax did commit, abort or
|
|
* crash. We know that xmax did mark the tuple for update, but
|
|
* it did not and will never actually update it.
|
|
*/
|
|
tuple->t_infomask |= HEAP_XMAX_INVALID;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
}
|
|
return HEAPTUPLE_LIVE;
|
|
}
|
|
|
|
if (!(tuple->t_infomask & HEAP_XMAX_COMMITTED))
|
|
{
|
|
if (TransactionIdIsInProgress(HeapTupleHeaderGetXmax(tuple)))
|
|
return HEAPTUPLE_DELETE_IN_PROGRESS;
|
|
else if (TransactionIdDidCommit(HeapTupleHeaderGetXmax(tuple)))
|
|
{
|
|
tuple->t_infomask |= HEAP_XMAX_COMMITTED;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
}
|
|
else
|
|
{
|
|
/*
|
|
* Not in Progress, Not Committed, so either Aborted or
|
|
* crashed
|
|
*/
|
|
tuple->t_infomask |= HEAP_XMAX_INVALID;
|
|
SetBufferCommitInfoNeedsSave(buffer);
|
|
return HEAPTUPLE_LIVE;
|
|
}
|
|
/* Should only get here if we set XMAX_COMMITTED */
|
|
Assert(tuple->t_infomask & HEAP_XMAX_COMMITTED);
|
|
}
|
|
|
|
/*
|
|
* Deleter committed, but check special cases.
|
|
*/
|
|
|
|
if (TransactionIdEquals(HeapTupleHeaderGetXmin(tuple),
|
|
HeapTupleHeaderGetXmax(tuple)))
|
|
{
|
|
/*
|
|
* inserter also deleted it, so it was never visible to anyone
|
|
* else
|
|
*/
|
|
return HEAPTUPLE_DEAD;
|
|
}
|
|
|
|
if (!TransactionIdPrecedes(HeapTupleHeaderGetXmax(tuple), OldestXmin))
|
|
{
|
|
/* deleting xact is too recent, tuple could still be visible */
|
|
return HEAPTUPLE_RECENTLY_DEAD;
|
|
}
|
|
|
|
/* Otherwise, it's dead and removable */
|
|
return HEAPTUPLE_DEAD;
|
|
}
|
|
|
|
|
|
/*
|
|
* GetTransactionSnapshot
|
|
* Get the appropriate snapshot for a new query in a transaction.
|
|
*
|
|
* The SerializableSnapshot is the first one taken in a transaction.
|
|
* In serializable mode we just use that one throughout the transaction.
|
|
* In read-committed mode, we take a new snapshot each time we are called.
|
|
*
|
|
* Note that the return value points at static storage that will be modified
|
|
* by future calls and by CommandCounterIncrement(). Callers should copy
|
|
* the result with CopySnapshot() if it is to be used very long.
|
|
*/
|
|
Snapshot
|
|
GetTransactionSnapshot(void)
|
|
{
|
|
/* First call in transaction? */
|
|
if (SerializableSnapshot == NULL)
|
|
{
|
|
SerializableSnapshot = GetSnapshotData(&SerializableSnapshotData, true);
|
|
return SerializableSnapshot;
|
|
}
|
|
|
|
if (IsXactIsoLevelSerializable)
|
|
return SerializableSnapshot;
|
|
|
|
LatestSnapshot = GetSnapshotData(&LatestSnapshotData, false);
|
|
|
|
return LatestSnapshot;
|
|
}
|
|
|
|
/*
|
|
* GetLatestSnapshot
|
|
* Get a snapshot that is up-to-date as of the current instant,
|
|
* even if we are executing in SERIALIZABLE mode.
|
|
*/
|
|
Snapshot
|
|
GetLatestSnapshot(void)
|
|
{
|
|
/* Should not be first call in transaction */
|
|
if (SerializableSnapshot == NULL)
|
|
elog(ERROR, "no snapshot has been set");
|
|
|
|
LatestSnapshot = GetSnapshotData(&LatestSnapshotData, false);
|
|
|
|
return LatestSnapshot;
|
|
}
|
|
|
|
/*
|
|
* CopySnapshot
|
|
* Copy the given snapshot.
|
|
*
|
|
* The copy is palloc'd in the current memory context.
|
|
*
|
|
* Note that this will not work on "special" snapshots.
|
|
*/
|
|
Snapshot
|
|
CopySnapshot(Snapshot snapshot)
|
|
{
|
|
Snapshot newsnap;
|
|
|
|
/* We allocate any XID array needed in the same palloc block. */
|
|
newsnap = (Snapshot) palloc(sizeof(SnapshotData) +
|
|
snapshot->xcnt * sizeof(TransactionId));
|
|
memcpy(newsnap, snapshot, sizeof(SnapshotData));
|
|
if (snapshot->xcnt > 0)
|
|
{
|
|
newsnap->xip = (TransactionId *) (newsnap + 1);
|
|
memcpy(newsnap->xip, snapshot->xip,
|
|
snapshot->xcnt * sizeof(TransactionId));
|
|
}
|
|
else
|
|
newsnap->xip = NULL;
|
|
|
|
return newsnap;
|
|
}
|
|
|
|
/*
|
|
* FreeSnapshot
|
|
* Free a snapshot previously copied with CopySnapshot.
|
|
*
|
|
* This is currently identical to pfree, but is provided for cleanliness.
|
|
*
|
|
* Do *not* apply this to the results of GetTransactionSnapshot or
|
|
* GetLatestSnapshot.
|
|
*/
|
|
void
|
|
FreeSnapshot(Snapshot snapshot)
|
|
{
|
|
pfree(snapshot);
|
|
}
|
|
|
|
/*
|
|
* FreeXactSnapshot
|
|
* Free snapshot(s) at end of transaction.
|
|
*/
|
|
void
|
|
FreeXactSnapshot(void)
|
|
{
|
|
/*
|
|
* We do not free the xip arrays for the static snapshot structs; they
|
|
* will be reused soon. So this is now just a state change to prevent
|
|
* outside callers from accessing the snapshots.
|
|
*/
|
|
SerializableSnapshot = NULL;
|
|
LatestSnapshot = NULL;
|
|
ActiveSnapshot = NULL; /* just for cleanliness */
|
|
}
|