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07cefdfb7a
Partially revert the previous patch I installed and replace it with a more general fix: any time a snapshot is pushed as Active, we need to ensure that it will not be modified in the future. This means that if the same snapshot is used as CurrentSnapshot, it needs to be copied separately. This affects serializable transactions only, because CurrentSnapshot has already been copied by RegisterSnapshot and so PushActiveSnapshot does not think it needs another copy. However, CommandCounterIncrement would modify CurrentSnapshot, whereas ActiveSnapshots must not have their command counters incremented. I say "partially" because the regression test I added for the previous bug has been kept. (This restores 8.3 behavior, because before snapmgr.c existed, any snapshot set as Active was copied.) Per bug report from Stuart Bishop in 6bc73d4c0910042358k3d1adff3qa36f8df75198ecea@mail.gmail.com
47 lines
1.5 KiB
C
47 lines
1.5 KiB
C
/*-------------------------------------------------------------------------
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*
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* snapmgr.h
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* POSTGRES snapshot manager
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*
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* Portions Copyright (c) 1996-2009, 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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* $PostgreSQL: pgsql/src/include/utils/snapmgr.h,v 1.7 2009/10/07 16:27:18 alvherre Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef SNAPMGR_H
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#define SNAPMGR_H
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#include "utils/resowner.h"
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#include "utils/snapshot.h"
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extern bool FirstSnapshotSet;
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extern TransactionId TransactionXmin;
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extern TransactionId RecentXmin;
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extern TransactionId RecentGlobalXmin;
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extern Snapshot GetTransactionSnapshot(void);
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extern Snapshot GetLatestSnapshot(void);
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extern void SnapshotSetCommandId(CommandId curcid);
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extern void PushActiveSnapshot(Snapshot snapshot);
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extern void PushUpdatedSnapshot(Snapshot snapshot);
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extern void PopActiveSnapshot(void);
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extern Snapshot GetActiveSnapshot(void);
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extern bool ActiveSnapshotSet(void);
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extern Snapshot RegisterSnapshot(Snapshot snapshot);
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extern void UnregisterSnapshot(Snapshot snapshot);
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extern Snapshot RegisterSnapshotOnOwner(Snapshot snapshot, ResourceOwner owner);
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extern void UnregisterSnapshotFromOwner(Snapshot snapshot, ResourceOwner owner);
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extern void AtSubCommit_Snapshot(int level);
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extern void AtSubAbort_Snapshot(int level);
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extern void AtEarlyCommit_Snapshot(void);
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extern void AtEOXact_Snapshot(bool isCommit);
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#endif /* SNAPMGR_H */
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