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/*-------------------------------------------------------------------------
*
* tqual.h--
* POSTGRES "time" qualification definitions.
*
* Should be moved/renamed... - vadim 07/28/98
*
* Copyright (c) 1994, Regents of the University of California
*
* $Id: tqual.h,v 1.14 1998/09/01 04:39:35 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef TQUAL_H
#define TQUAL_H
#include <access/htup.h>
typedef struct SnapshotData
{
TransactionId xmin; /* XID < xmin are visible to me */
TransactionId xmax; /* XID > xmax are invisible to me */
TransactionId *xip; /* array of xacts in progress */
} SnapshotData;
typedef SnapshotData *Snapshot;
#define IsSnapshotNow(snapshot) ((Snapshot) snapshot == (Snapshot) 0x0)
#define IsSnapshotSelf(snapshot) ((Snapshot) snapshot == (Snapshot) 0x1)
#define SnapshotNow ((Snapshot) 0x0)
#define SnapshotSelf ((Snapshot) 0x1)
extern TransactionId HeapSpecialTransactionId;
extern CommandId HeapSpecialCommandId;
/*
* HeapTupleSatisfiesVisibility --
* True iff heap tuple satsifies a time qual.
*
* Note:
* Assumes heap tuple is valid.
*/
#define HeapTupleSatisfiesVisibility(tuple, snapshot) \
( \
TransactionIdEquals((tuple)->t_xmax, AmiTransactionId) ? \
false \
: \
( \
(IsSnapshotSelf(snapshot) || heapisoverride()) ? \
HeapTupleSatisfiesItself(tuple) \
: \
HeapTupleSatisfiesNow(tuple) \
) \
)
#define heapisoverride() \
( \
(!TransactionIdIsValid(HeapSpecialTransactionId)) ? \
false \
: \
( \
(!TransactionIdEquals(GetCurrentTransactionId(), \
HeapSpecialTransactionId) || \
GetCurrentCommandId() != HeapSpecialCommandId) ? \
( \
HeapSpecialTransactionId = InvalidTransactionId, \
false \
) \
: \
true \
) \
)
extern bool HeapTupleSatisfiesItself(HeapTuple tuple);
extern bool HeapTupleSatisfiesNow(HeapTuple tuple);
extern void setheapoverride(bool on);
#endif /* TQUAL_H */
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