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   1  /*-------------------------------------------------------------------------
   2  *
   3  * htup.h
   4  *        POSTGRES heap tuple definitions.
   5  *
   6  *
   7  * Copyright (c) 1994, Regents of the University of California
   8  *
   9  * $Id: htup.h,v 1.27 1999/12/21 00:06:42 wieck Exp $
  10  *
  11  *-------------------------------------------------------------------------
  12  */
  13 #ifndef HTUP_H
  14 #define HTUP_H
  15
  16 #include "storage/bufpage.h"
  17
  18 #define MinHeapTupleBitmapSize  32              /* 8 * 4 */
  19
  20 /* check these, they are likely to be more severely limited by t_hoff */
  21
  22 #define MaxHeapAttributeNumber  1600    /* 8 * 200 */
  23
  24 /*
  25  * to avoid wasting space, the attributes should be layed out in such a
  26  * way to reduce structure padding.
  27  */
  28 typedef struct HeapTupleHeaderData
  29 {
  30         Oid                     t_oid;                  /* OID of this tuple -- 4 bytes */
  31
  32         CommandId       t_cmin;                 /* insert CID stamp -- 4 bytes each */
  33         CommandId       t_cmax;                 /* delete CommandId stamp */
  34
  35         TransactionId t_xmin;           /* insert XID stamp -- 4 bytes each */
  36         TransactionId t_xmax;           /* delete XID stamp */
  37
  38         ItemPointerData t_ctid;         /* current TID of this or newer tuple */
  39
  40         int16           t_natts;                /* number of attributes */
  41
  42         uint16          t_infomask;             /* various infos */
  43
  44         uint8           t_hoff;                 /* sizeof tuple header */
  45
  46         bits8           t_bits[MinHeapTupleBitmapSize / 8];
  47         /* bit map of domains */
  48
  49         /* MORE DATA FOLLOWS AT END OF STRUCT */
  50 } HeapTupleHeaderData;
  51
  52 typedef HeapTupleHeaderData *HeapTupleHeader;
  53
  54 #define MinTupleSize    (MAXALIGN(sizeof (PageHeaderData)) + \
  55                                                  MAXALIGN(sizeof(HeapTupleHeaderData)) + \
  56                                                  MAXALIGN(sizeof(char)))
  57
  58 #define MaxTupleSize    (BLCKSZ - MinTupleSize)
  59
  60 #define MaxAttrSize             (MaxTupleSize - MAXALIGN(sizeof(HeapTupleHeaderData)))
  61
  62 #define SelfItemPointerAttributeNumber                  (-1)
  63 #define ObjectIdAttributeNumber                                 (-2)
  64 #define MinTransactionIdAttributeNumber                 (-3)
  65 #define MinCommandIdAttributeNumber                             (-4)
  66 #define MaxTransactionIdAttributeNumber                 (-5)
  67 #define MaxCommandIdAttributeNumber                             (-6)
  68 #define FirstLowInvalidHeapAttributeNumber              (-7)
  69
  70 /* If you make any changes above, the order off offsets in this must change */
  71 extern long heap_sysoffset[];
  72
  73 /*
  74  * This new HeapTuple for version >= 6.5 and this is why it was changed:
  75  *
  76  * 1. t_len moved off on-disk tuple data - ItemIdData is used to get len;
  77  * 2. t_ctid above is not self tuple TID now - it may point to
  78  *        updated version of tuple (required by MVCC);
  79  * 3. someday someone let tuple to cross block boundaries -
  80  *        he have to add something below...
  81  *
  82  * Change for 7.0:
  83  *    Up to now t_data could be NULL, the memory location directly following
  84  *    HeapTupleData or pointing into a buffer. Now, it could also point to
  85  *    a separate allocation that was done in the t_datamcxt memory context.
  86  */
  87 typedef struct HeapTupleData
  88 {
  89         uint32          t_len;                  /* length of *t_data */
  90         ItemPointerData t_self;         /* SelfItemPointer */
  91         MemoryContext   t_datamcxt; /* */
  92         HeapTupleHeader t_data;         /* */
  93 } HeapTupleData;
  94
  95 typedef HeapTupleData *HeapTuple;
  96
  97 #define HEAPTUPLESIZE   MAXALIGN(sizeof(HeapTupleData))
  98
  99
 100 /* ----------------
 101  *              support macros
 102  * ----------------
 103  */
 104 #define GETSTRUCT(TUP) (((char *)((HeapTuple)(TUP))->t_data) + \
 105                                                 ((HeapTuple)(TUP))->t_data->t_hoff)
 106
 107
 108 /*
 109  * BITMAPLEN(NATTS) -
 110  *              Computes minimum size of bitmap given number of domains.
 111  */
 112 #define BITMAPLEN(NATTS) \
 113                 ((((((int)(NATTS) - 1) >> 3) + 4 - (MinHeapTupleBitmapSize >> 3)) \
 114                   & ~03) + (MinHeapTupleBitmapSize >> 3))
 115
 116 /*
 117  * HeapTupleIsValid
 118  *              True iff the heap tuple is valid.
 119  */
 120 #define HeapTupleIsValid(tuple) PointerIsValid(tuple)
 121
 122 /*
 123  * information stored in t_infomask:
 124  */
 125 #define HEAP_HASNULL                    0x0001  /* has null attribute(s) */
 126 #define HEAP_HASVARLENA                 0x0002  /* has variable length
 127                                                                                  * attribute(s) */
 128 #define HEAP_HASEXTERNAL                0x0004  /* has external stored */
 129                                                                                 /* attribute(s) */
 130 #define HEAP_HASCOMPRESSED              0x0008  /* has compressed stored */
 131                                                                                 /* attribute(s) */
 132 #define HEAP_HASEXTENDED                0x000C  /* the two above combined */
 133 #define HEAP_XMIN_COMMITTED             0x0100  /* t_xmin committed */
 134 #define HEAP_XMIN_INVALID               0x0200  /* t_xmin invalid/aborted */
 135 #define HEAP_XMAX_COMMITTED             0x0400  /* t_xmax committed */
 136 #define HEAP_XMAX_INVALID               0x0800  /* t_xmax invalid/aborted */
 137 #define HEAP_MARKED_FOR_UPDATE  0x1000  /* marked for UPDATE */
 138 #define HEAP_UPDATED                    0x2000  /* this is UPDATEd version of row */
 139 #define HEAP_MOVED_OFF                  0x4000  /* removed or moved to another
 140                                                                                  * place by vacuum */
 141 #define HEAP_MOVED_IN                   0x8000  /* moved from another place by
 142                                                                                  * vacuum */
 143
 144 #define HEAP_XACT_MASK                  0xFF00  /* */
 145
 146 #define HeapTupleNoNulls(tuple) \
 147                 (!(((HeapTuple) (tuple))->t_data->t_infomask & HEAP_HASNULL))
 148
 149 #define HeapTupleAllFixed(tuple) \
 150                 (!(((HeapTuple) (tuple))->t_data->t_infomask & HEAP_HASVARLENA))
 151
 152 #define HeapTupleHasExternal(tuple) \
 153                 ((((HeapTuple)(tuple))->t_data->t_infomask & HEAP_HASEXTERNAL) != 0)
 154
 155 #define HeapTupleHasCompressed(tuple) \
 156                 ((((HeapTuple)(tuple))->t_data->t_infomask & HEAP_HASCOMPRESSED) != 0)
 157
 158 #define HeapTupleHasExtended(tuple) \
 159                 ((((HeapTuple)(tuple))->t_data->t_infomask & HEAP_HASEXTENDED) != 0)
 160
 161 #endif   /* HTUP_H */