granicus.if.org Git - postgresql/blob - src/include/utils/tqual.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * tqual.h
   4  *        POSTGRES "time qualification" definitions, ie, tuple visibility rules.
   5  *
   6  *        Should be moved/renamed...    - vadim 07/28/98
   7  *
   8  * Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
   9  * Portions Copyright (c) 1994, Regents of the University of California
  10  *
  11  * src/include/utils/tqual.h
  12  *
  13  *-------------------------------------------------------------------------
  14  */
  15 #ifndef TQUAL_H
  16 #define TQUAL_H
  17
  18 #include "utils/snapshot.h"
  19
  20
  21 /* Static variables representing various special snapshot semantics */
  22 extern PGDLLIMPORT SnapshotData SnapshotSelfData;
  23 extern PGDLLIMPORT SnapshotData SnapshotAnyData;
  24 extern PGDLLIMPORT SnapshotData SnapshotToastData;
  25
  26 #define SnapshotSelf            (&SnapshotSelfData)
  27 #define SnapshotAny                     (&SnapshotAnyData)
  28 #define SnapshotToast           (&SnapshotToastData)
  29
  30 /*
  31  * We don't provide a static SnapshotDirty variable because it would be
  32  * non-reentrant.  Instead, users of that snapshot type should declare a
  33  * local variable of type SnapshotData, and initialize it with this macro.
  34  */
  35 #define InitDirtySnapshot(snapshotdata)  \
  36         ((snapshotdata).satisfies = HeapTupleSatisfiesDirty)
  37
  38 /* This macro encodes the knowledge of which snapshots are MVCC-safe */
  39 #define IsMVCCSnapshot(snapshot)  \
  40         ((snapshot)->satisfies == HeapTupleSatisfiesMVCC)
  41
  42 /*
  43  * HeapTupleSatisfiesVisibility
  44  *              True iff heap tuple satisfies a time qual.
  45  *
  46  * Notes:
  47  *      Assumes heap tuple is valid.
  48  *      Beware of multiple evaluations of snapshot argument.
  49  *      Hint bits in the HeapTuple's t_infomask may be updated as a side effect;
  50  *      if so, the indicated buffer is marked dirty.
  51  */
  52 #define HeapTupleSatisfiesVisibility(tuple, snapshot, buffer) \
  53         ((*(snapshot)->satisfies) (tuple, snapshot, buffer))
  54
  55 /* Result codes for HeapTupleSatisfiesVacuum */
  56 typedef enum
  57 {
  58         HEAPTUPLE_DEAD,                         /* tuple is dead and deletable */
  59         HEAPTUPLE_LIVE,                         /* tuple is live (committed, no deleter) */
  60         HEAPTUPLE_RECENTLY_DEAD,        /* tuple is dead, but not deletable yet */
  61         HEAPTUPLE_INSERT_IN_PROGRESS,           /* inserting xact is still in progress */
  62         HEAPTUPLE_DELETE_IN_PROGRESS    /* deleting xact is still in progress */
  63 } HTSV_Result;
  64
  65 /* These are the "satisfies" test routines for the various snapshot types */
  66 extern bool HeapTupleSatisfiesMVCC(HeapTuple htup,
  67                                            Snapshot snapshot, Buffer buffer);
  68 extern bool HeapTupleSatisfiesSelf(HeapTuple htup,
  69                                            Snapshot snapshot, Buffer buffer);
  70 extern bool HeapTupleSatisfiesAny(HeapTuple htup,
  71                                           Snapshot snapshot, Buffer buffer);
  72 extern bool HeapTupleSatisfiesToast(HeapTuple htup,
  73                                                 Snapshot snapshot, Buffer buffer);
  74 extern bool HeapTupleSatisfiesDirty(HeapTuple htup,
  75                                                 Snapshot snapshot, Buffer buffer);
  76
  77 /* Special "satisfies" routines with different APIs */
  78 extern HTSU_Result HeapTupleSatisfiesUpdate(HeapTuple htup,
  79                                                  CommandId curcid, Buffer buffer);
  80 extern HTSV_Result HeapTupleSatisfiesVacuum(HeapTuple htup,
  81                                                  TransactionId OldestXmin, Buffer buffer);
  82 extern bool HeapTupleIsSurelyDead(HeapTuple htup,
  83                                           TransactionId OldestXmin);
  84
  85 extern void HeapTupleSetHintBits(HeapTupleHeader tuple, Buffer buffer,
  86                                          uint16 infomask, TransactionId xid);
  87 extern bool HeapTupleHeaderIsOnlyLocked(HeapTupleHeader tuple);
  88
  89 #endif   /* TQUAL_H */