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) 1996-2015, 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 extern PGDLLIMPORT SnapshotData CatalogSnapshotData;
  26
  27 #define SnapshotSelf            (&SnapshotSelfData)
  28 #define SnapshotAny                     (&SnapshotAnyData)
  29 #define SnapshotToast           (&SnapshotToastData)
  30
  31 /*
  32  * We don't provide a static SnapshotDirty variable because it would be
  33  * non-reentrant.  Instead, users of that snapshot type should declare a
  34  * local variable of type SnapshotData, and initialize it with this macro.
  35  */
  36 #define InitDirtySnapshot(snapshotdata)  \
  37         ((snapshotdata).satisfies = HeapTupleSatisfiesDirty)
  38
  39 /* This macro encodes the knowledge of which snapshots are MVCC-safe */
  40 #define IsMVCCSnapshot(snapshot)  \
  41         ((snapshot)->satisfies == HeapTupleSatisfiesMVCC || \
  42          (snapshot)->satisfies == HeapTupleSatisfiesHistoricMVCC)
  43
  44 /*
  45  * HeapTupleSatisfiesVisibility
  46  *              True iff heap tuple satisfies a time qual.
  47  *
  48  * Notes:
  49  *      Assumes heap tuple is valid.
  50  *      Beware of multiple evaluations of snapshot argument.
  51  *      Hint bits in the HeapTuple's t_infomask may be updated as a side effect;
  52  *      if so, the indicated buffer is marked dirty.
  53  */
  54 #define HeapTupleSatisfiesVisibility(tuple, snapshot, buffer) \
  55         ((*(snapshot)->satisfies) (tuple, snapshot, buffer))
  56
  57 /* Result codes for HeapTupleSatisfiesVacuum */
  58 typedef enum
  59 {
  60         HEAPTUPLE_DEAD,                         /* tuple is dead and deletable */
  61         HEAPTUPLE_LIVE,                         /* tuple is live (committed, no deleter) */
  62         HEAPTUPLE_RECENTLY_DEAD,        /* tuple is dead, but not deletable yet */
  63         HEAPTUPLE_INSERT_IN_PROGRESS,           /* inserting xact is still in progress */
  64         HEAPTUPLE_DELETE_IN_PROGRESS    /* deleting xact is still in progress */
  65 } HTSV_Result;
  66
  67 /* These are the "satisfies" test routines for the various snapshot types */
  68 extern bool HeapTupleSatisfiesMVCC(HeapTuple htup,
  69                                            Snapshot snapshot, Buffer buffer);
  70 extern bool HeapTupleSatisfiesSelf(HeapTuple htup,
  71                                            Snapshot snapshot, Buffer buffer);
  72 extern bool HeapTupleSatisfiesAny(HeapTuple htup,
  73                                           Snapshot snapshot, Buffer buffer);
  74 extern bool HeapTupleSatisfiesToast(HeapTuple htup,
  75                                                 Snapshot snapshot, Buffer buffer);
  76 extern bool HeapTupleSatisfiesDirty(HeapTuple htup,
  77                                                 Snapshot snapshot, Buffer buffer);
  78 extern bool HeapTupleSatisfiesHistoricMVCC(HeapTuple htup,
  79                                                            Snapshot snapshot, Buffer buffer);
  80
  81 /* Special "satisfies" routines with different APIs */
  82 extern HTSU_Result HeapTupleSatisfiesUpdate(HeapTuple htup,
  83                                                  CommandId curcid, Buffer buffer);
  84 extern HTSV_Result HeapTupleSatisfiesVacuum(HeapTuple htup,
  85                                                  TransactionId OldestXmin, Buffer buffer);
  86 extern bool HeapTupleIsSurelyDead(HeapTuple htup,
  87                                           TransactionId OldestXmin);
  88
  89 extern void HeapTupleSetHintBits(HeapTupleHeader tuple, Buffer buffer,
  90                                          uint16 infomask, TransactionId xid);
  91 extern bool HeapTupleHeaderIsOnlyLocked(HeapTupleHeader tuple);
  92
  93 /*
  94  * To avoid leaking too much knowledge about reorderbuffer implementation
  95  * details this is implemented in reorderbuffer.c not tqual.c.
  96  */
  97 extern bool ResolveCminCmaxDuringDecoding(struct HTAB *tuplecid_data,
  98                                                           Snapshot snapshot,
  99                                                           HeapTuple htup,
 100                                                           Buffer buffer,
 101                                                           CommandId *cmin, CommandId *cmax);
 102 #endif   /* TQUAL_H */