src/include/utils/tqual.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * tqual.h
   4  *        POSTGRES "time" qualification definitions.
   5  *
   6  *        Should be moved/renamed...    - vadim 07/28/98
   7  *
   8  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
   9  * Portions Copyright (c) 1994, Regents of the University of California
  10  *
  11  * $Id: tqual.h,v 1.32 2001/07/12 04:11:13 tgl Exp $
  12  *
  13  *-------------------------------------------------------------------------
  14  */
  15 #ifndef TQUAL_H
  16 #define TQUAL_H
  17
  18 #include "access/htup.h"
  19 #include "access/xact.h"
  20
  21
  22 typedef struct SnapshotData
  23 {
  24         TransactionId xmin;                     /* XID < xmin are visible to me */
  25         TransactionId xmax;                     /* XID >= xmax are invisible to me */
  26         uint32          xcnt;                   /* # of xact ids in xip[] */
  27         TransactionId *xip;                     /* array of xact IDs in progress */
  28         /* note: all ids in xip[] satisfy xmin <= xip[i] < xmax */
  29         ItemPointerData tid;            /* required for Dirty snapshot -:( */
  30 } SnapshotData;
  31
  32 typedef SnapshotData *Snapshot;
  33
  34 #define SnapshotNow                                     ((Snapshot) 0x0)
  35 #define SnapshotSelf                            ((Snapshot) 0x1)
  36 #define SnapshotAny                                     ((Snapshot) 0x2)
  37
  38 extern DLLIMPORT Snapshot SnapshotDirty;
  39 extern DLLIMPORT Snapshot QuerySnapshot;
  40 extern DLLIMPORT Snapshot SerializableSnapshot;
  41
  42 extern bool ReferentialIntegritySnapshotOverride;
  43
  44 #define IsSnapshotNow(snapshot)         ((Snapshot) (snapshot) == SnapshotNow)
  45 #define IsSnapshotSelf(snapshot)        ((Snapshot) (snapshot) == SnapshotSelf)
  46 #define IsSnapshotAny(snapshot)         ((Snapshot) (snapshot) == SnapshotAny)
  47 #define IsSnapshotDirty(snapshot)       ((Snapshot) (snapshot) == SnapshotDirty)
  48
  49
  50 /*
  51  * HeapTupleSatisfiesVisibility
  52  *              True iff heap tuple satsifies a time qual.
  53  *
  54  * Notes:
  55  *              Assumes heap tuple is valid.
  56  *              Beware of multiple evaluations of arguments.
  57  */
  58 #define HeapTupleSatisfiesVisibility(tuple, snapshot) \
  59 ( \
  60         TransactionIdEquals((tuple)->t_data->t_xmax, AmiTransactionId) ? \
  61                 false \
  62         : \
  63         ( \
  64                 IsSnapshotAny(snapshot) ? \
  65                         true \
  66                 : \
  67                         (IsSnapshotSelf(snapshot) ? \
  68                                 HeapTupleSatisfiesItself((tuple)->t_data) \
  69                         : \
  70                                 (IsSnapshotNow(snapshot) ? \
  71                                         HeapTupleSatisfiesNow((tuple)->t_data) \
  72                                 : \
  73                                         (IsSnapshotDirty(snapshot) ? \
  74                                                 HeapTupleSatisfiesDirty((tuple)->t_data) \
  75                                         : \
  76                                                 HeapTupleSatisfiesSnapshot((tuple)->t_data, snapshot) \
  77                                         ) \
  78                         ) \
  79                 ) \
  80         ) \
  81 )
  82
  83 /* Result codes for HeapTupleSatisfiesUpdate */
  84 #define HeapTupleMayBeUpdated           0
  85 #define HeapTupleInvisible                      1
  86 #define HeapTupleSelfUpdated            2
  87 #define HeapTupleUpdated                        3
  88 #define HeapTupleBeingUpdated           4
  89
  90 /* Result codes for HeapTupleSatisfiesVacuum */
  91 typedef enum
  92 {
  93         HEAPTUPLE_DEAD,                         /* tuple is dead and deletable */
  94         HEAPTUPLE_LIVE,                         /* tuple is live (committed, no deleter) */
  95         HEAPTUPLE_RECENTLY_DEAD,        /* tuple is dead, but not deletable yet */
  96         HEAPTUPLE_INSERT_IN_PROGRESS, /* inserting xact is still in progress */
  97         HEAPTUPLE_DELETE_IN_PROGRESS /* deleting xact is still in progress */
  98 } HTSV_Result;
  99
 100 extern bool HeapTupleSatisfiesItself(HeapTupleHeader tuple);
 101 extern bool HeapTupleSatisfiesNow(HeapTupleHeader tuple);
 102 extern bool HeapTupleSatisfiesDirty(HeapTupleHeader tuple);
 103 extern bool HeapTupleSatisfiesSnapshot(HeapTupleHeader tuple,
 104                                                    Snapshot snapshot);
 105 extern int      HeapTupleSatisfiesUpdate(HeapTuple tuple);
 106 extern HTSV_Result HeapTupleSatisfiesVacuum(HeapTupleHeader tuple,
 107                                                                                         TransactionId XmaxRecent);
 108
 109 extern Snapshot GetSnapshotData(bool serializable);
 110 extern void SetQuerySnapshot(void);
 111 extern void FreeXactSnapshot(void);
 112
 113 #endif   /* TQUAL_H */