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/*-------------------------------------------------------------------------
*
* tqual.h
* POSTGRES "time qualification" definitions, ie, tuple visibility rules.
*
* Should be moved/renamed... - vadim 07/28/98
*
* Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/utils/tqual.h
*
*-------------------------------------------------------------------------
*/
#ifndef TQUAL_H
#define TQUAL_H
#include "utils/snapshot.h"
#include "access/xlogdefs.h"
/* Static variables representing various special snapshot semantics */
extern PGDLLIMPORT SnapshotData SnapshotSelfData;
extern PGDLLIMPORT SnapshotData SnapshotAnyData;
extern PGDLLIMPORT SnapshotData CatalogSnapshotData;
#define SnapshotSelf (&SnapshotSelfData)
#define SnapshotAny (&SnapshotAnyData)
/* This macro encodes the knowledge of which snapshots are MVCC-safe */
#define IsMVCCSnapshot(snapshot) \
((snapshot)->satisfies == HeapTupleSatisfiesMVCC || \
(snapshot)->satisfies == HeapTupleSatisfiesHistoricMVCC)
/*
* HeapTupleSatisfiesVisibility
* True iff heap tuple satisfies a time qual.
*
* Notes:
* Assumes heap tuple is valid.
* Beware of multiple evaluations of snapshot argument.
* Hint bits in the HeapTuple's t_infomask may be updated as a side effect;
* if so, the indicated buffer is marked dirty.
*/
#define HeapTupleSatisfiesVisibility(tuple, snapshot, buffer) \
((*(snapshot)->satisfies) (tuple, snapshot, buffer))
/* Result codes for HeapTupleSatisfiesVacuum */
typedef enum
{
HEAPTUPLE_DEAD, /* tuple is dead and deletable */
HEAPTUPLE_LIVE, /* tuple is live (committed, no deleter) */
HEAPTUPLE_RECENTLY_DEAD, /* tuple is dead, but not deletable yet */
HEAPTUPLE_INSERT_IN_PROGRESS, /* inserting xact is still in progress */
HEAPTUPLE_DELETE_IN_PROGRESS /* deleting xact is still in progress */
} HTSV_Result;
/* These are the "satisfies" test routines for the various snapshot types */
extern bool HeapTupleSatisfiesMVCC(HeapTuple htup,
Snapshot snapshot, Buffer buffer);
extern bool HeapTupleSatisfiesSelf(HeapTuple htup,
Snapshot snapshot, Buffer buffer);
extern bool HeapTupleSatisfiesAny(HeapTuple htup,
Snapshot snapshot, Buffer buffer);
extern bool HeapTupleSatisfiesToast(HeapTuple htup,
Snapshot snapshot, Buffer buffer);
extern bool HeapTupleSatisfiesDirty(HeapTuple htup,
Snapshot snapshot, Buffer buffer);
extern bool HeapTupleSatisfiesHistoricMVCC(HeapTuple htup,
Snapshot snapshot, Buffer buffer);
/* Special "satisfies" routines with different APIs */
extern HTSU_Result HeapTupleSatisfiesUpdate(HeapTuple htup,
CommandId curcid, Buffer buffer);
extern HTSV_Result HeapTupleSatisfiesVacuum(HeapTuple htup,
TransactionId OldestXmin, Buffer buffer);
extern bool HeapTupleIsSurelyDead(HeapTuple htup,
TransactionId OldestXmin);
extern bool XidInMVCCSnapshot(TransactionId xid, Snapshot snapshot);
extern void HeapTupleSetHintBits(HeapTupleHeader tuple, Buffer buffer,
uint16 infomask, TransactionId xid);
extern bool HeapTupleHeaderIsOnlyLocked(HeapTupleHeader tuple);
/*
* To avoid leaking too much knowledge about reorderbuffer implementation
* details this is implemented in reorderbuffer.c not tqual.c.
*/
struct HTAB;
extern bool ResolveCminCmaxDuringDecoding(struct HTAB *tuplecid_data,
Snapshot snapshot,
HeapTuple htup,
Buffer buffer,
CommandId *cmin, CommandId *cmax);
/*
* We don't provide a static SnapshotDirty variable because it would be
* non-reentrant. Instead, users of that snapshot type should declare a
* local variable of type SnapshotData, and initialize it with this macro.
*/
#define InitDirtySnapshot(snapshotdata) \
((snapshotdata).satisfies = HeapTupleSatisfiesDirty)
/*
* Similarly, some initialization is required for SnapshotToast. We need
* to set lsn and whenTaken correctly to support snapshot_too_old.
*/
#define InitToastSnapshot(snapshotdata, l, w) \
((snapshotdata).satisfies = HeapTupleSatisfiesToast, \
(snapshotdata).lsn = (l), \
(snapshotdata).whenTaken = (w))
#endif /* TQUAL_H */
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