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139 lines
4.6 KiB
C
139 lines
4.6 KiB
C
/*-------------------------------------------------------------------------
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*
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* tqual.h
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* POSTGRES "time qualification" definitions, ie, tuple visibility rules.
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*
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* Should be moved/renamed... - vadim 07/28/98
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*
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* Portions Copyright (c) 1996-2005, 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/tqual.h,v 1.56 2005/03/20 23:40:34 neilc Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef TQUAL_H
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#define TQUAL_H
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#include "access/htup.h"
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#include "access/xact.h"
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#include "storage/buf.h"
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/*
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* "Regular" snapshots are pointers to a SnapshotData structure.
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*
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* We also have some "special" snapshot values that have fixed meanings
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* and don't need any backing SnapshotData. These are encoded by small
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* integer values, which of course is a gross violation of ANSI C, but
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* it works fine on all known platforms.
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*
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* SnapshotDirty is an even more special case: its semantics are fixed,
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* but there is a backing SnapshotData struct for it. That struct is
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* actually used as *output* data from tqual.c, not input into it.
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* (But hey, SnapshotDirty ought to have a dirty implementation, no? ;-))
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*/
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typedef struct SnapshotData
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{
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TransactionId xmin; /* XID < xmin are visible to me */
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TransactionId xmax; /* XID >= xmax are invisible to me */
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uint32 xcnt; /* # of xact ids in xip[] */
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TransactionId *xip; /* array of xact IDs in progress */
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/* note: all ids in xip[] satisfy xmin <= xip[i] < xmax */
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CommandId curcid; /* in my xact, CID < curcid are visible */
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ItemPointerData tid; /* required for Dirty snapshot -:( */
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} SnapshotData;
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typedef SnapshotData *Snapshot;
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/* Special snapshot values: */
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#define InvalidSnapshot ((Snapshot) 0x0) /* same as NULL */
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#define SnapshotNow ((Snapshot) 0x1)
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#define SnapshotSelf ((Snapshot) 0x2)
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#define SnapshotAny ((Snapshot) 0x3)
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#define SnapshotToast ((Snapshot) 0x4)
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extern DLLIMPORT Snapshot SnapshotDirty;
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extern DLLIMPORT Snapshot SerializableSnapshot;
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extern DLLIMPORT Snapshot LatestSnapshot;
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extern DLLIMPORT Snapshot ActiveSnapshot;
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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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/*
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* HeapTupleSatisfiesVisibility
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* True iff heap tuple satisfies a time qual.
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*
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* Notes:
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* Assumes heap tuple is valid.
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* Beware of multiple evaluations of snapshot argument.
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*/
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#define HeapTupleSatisfiesVisibility(tuple, snapshot, buffer) \
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((snapshot) == SnapshotNow ? \
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HeapTupleSatisfiesNow((tuple)->t_data, buffer) \
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: \
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((snapshot) == SnapshotSelf ? \
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HeapTupleSatisfiesItself((tuple)->t_data, buffer) \
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: \
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((snapshot) == SnapshotAny ? \
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true \
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: \
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((snapshot) == SnapshotToast ? \
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HeapTupleSatisfiesToast((tuple)->t_data, buffer) \
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: \
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((snapshot) == SnapshotDirty ? \
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HeapTupleSatisfiesDirty((tuple)->t_data, buffer) \
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: \
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HeapTupleSatisfiesSnapshot((tuple)->t_data, snapshot, buffer) \
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) \
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) \
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) \
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) \
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)
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/* Result codes for HeapTupleSatisfiesUpdate */
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typedef enum
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{
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HeapTupleMayBeUpdated,
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HeapTupleInvisible,
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HeapTupleSelfUpdated,
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HeapTupleUpdated,
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HeapTupleBeingUpdated
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} HTSU_Result;
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/* Result codes for HeapTupleSatisfiesVacuum */
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typedef enum
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{
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HEAPTUPLE_DEAD, /* tuple is dead and deletable */
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HEAPTUPLE_LIVE, /* tuple is live (committed, no deleter) */
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HEAPTUPLE_RECENTLY_DEAD, /* tuple is dead, but not deletable yet */
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HEAPTUPLE_INSERT_IN_PROGRESS, /* inserting xact is still in progress */
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HEAPTUPLE_DELETE_IN_PROGRESS /* deleting xact is still in progress */
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} HTSV_Result;
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extern bool HeapTupleSatisfiesItself(HeapTupleHeader tuple, Buffer buffer);
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extern bool HeapTupleSatisfiesNow(HeapTupleHeader tuple, Buffer buffer);
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extern bool HeapTupleSatisfiesDirty(HeapTupleHeader tuple, Buffer buffer);
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extern bool HeapTupleSatisfiesToast(HeapTupleHeader tuple, Buffer buffer);
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extern bool HeapTupleSatisfiesSnapshot(HeapTupleHeader tuple,
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Snapshot snapshot, Buffer buffer);
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extern HTSU_Result HeapTupleSatisfiesUpdate(HeapTupleHeader tuple,
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CommandId curcid, Buffer buffer);
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extern HTSV_Result HeapTupleSatisfiesVacuum(HeapTupleHeader tuple,
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TransactionId OldestXmin, Buffer buffer);
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extern Snapshot GetTransactionSnapshot(void);
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extern Snapshot GetLatestSnapshot(void);
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extern Snapshot CopySnapshot(Snapshot snapshot);
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extern void FreeSnapshot(Snapshot snapshot);
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extern void FreeXactSnapshot(void);
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/* in sinval.c; declared here to avoid including tqual.h in sinval.h: */
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extern Snapshot GetSnapshotData(Snapshot snapshot, bool serializable);
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#endif /* TQUAL_H */
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