granicus.if.org Git - postgresql/blob - src/backend/utils/adt/tid.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * tid.c
   4  *        Functions for the built-in type tuple id
   5  *
   6  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        $Header: /cvsroot/pgsql/src/backend/utils/adt/tid.c,v 1.27 2001/09/17 00:29:10 tgl Exp $
  12  *
  13  * NOTES
  14  *        input routine largely stolen from boxin().
  15  *
  16  *-------------------------------------------------------------------------
  17  */
  18
  19 #include "postgres.h"
  20
  21 #include "access/heapam.h"
  22 #include "utils/builtins.h"
  23
  24 #define DatumGetItemPointer(X)   ((ItemPointer) DatumGetPointer(X))
  25 #define ItemPointerGetDatum(X)   PointerGetDatum(X)
  26 #define PG_GETARG_ITEMPOINTER(n) DatumGetItemPointer(PG_GETARG_DATUM(n))
  27 #define PG_RETURN_ITEMPOINTER(x) return ItemPointerGetDatum(x)
  28
  29 #define LDELIM                  '('
  30 #define RDELIM                  ')'
  31 #define DELIM                   ','
  32 #define NTIDARGS                2
  33
  34 /* ----------------------------------------------------------------
  35  *              tidin
  36  * ----------------------------------------------------------------
  37  */
  38 Datum
  39 tidin(PG_FUNCTION_ARGS)
  40 {
  41         char       *str = PG_GETARG_CSTRING(0);
  42         char       *p,
  43                            *coord[NTIDARGS];
  44         int                     i;
  45         ItemPointer result;
  46         BlockNumber blockNumber;
  47         OffsetNumber offsetNumber;
  48
  49         for (i = 0, p = str; *p && i < NTIDARGS && *p != RDELIM; p++)
  50                 if (*p == DELIM || (*p == LDELIM && !i))
  51                         coord[i++] = p + 1;
  52
  53         if (i < NTIDARGS)
  54                 elog(ERROR, "invalid tid format: '%s'", str);
  55
  56         blockNumber = (BlockNumber) atoi(coord[0]);
  57         offsetNumber = (OffsetNumber) atoi(coord[1]);
  58
  59         result = (ItemPointer) palloc(sizeof(ItemPointerData));
  60
  61         ItemPointerSet(result, blockNumber, offsetNumber);
  62
  63         PG_RETURN_ITEMPOINTER(result);
  64 }
  65
  66 /* ----------------------------------------------------------------
  67  *              tidout
  68  * ----------------------------------------------------------------
  69  */
  70 Datum
  71 tidout(PG_FUNCTION_ARGS)
  72 {
  73         ItemPointer itemPtr = PG_GETARG_ITEMPOINTER(0);
  74         BlockId         blockId;
  75         BlockNumber blockNumber;
  76         OffsetNumber offsetNumber;
  77         char            buf[32];
  78         static char *invalidTid = "()";
  79
  80         if (!ItemPointerIsValid(itemPtr))
  81                 PG_RETURN_CSTRING(pstrdup(invalidTid));
  82
  83         blockId = &(itemPtr->ip_blkid);
  84
  85         blockNumber = BlockIdGetBlockNumber(blockId);
  86         offsetNumber = itemPtr->ip_posid;
  87
  88         sprintf(buf, "(%d,%d)", (int) blockNumber, (int) offsetNumber);
  89
  90         PG_RETURN_CSTRING(pstrdup(buf));
  91 }
  92
  93 /*****************************************************************************
  94  *       PUBLIC ROUTINES                                                                                                                 *
  95  *****************************************************************************/
  96
  97 Datum
  98 tideq(PG_FUNCTION_ARGS)
  99 {
 100         ItemPointer arg1 = PG_GETARG_ITEMPOINTER(0);
 101         ItemPointer arg2 = PG_GETARG_ITEMPOINTER(1);
 102
 103         PG_RETURN_BOOL(BlockIdGetBlockNumber(&(arg1->ip_blkid)) ==
 104                                    BlockIdGetBlockNumber(&(arg2->ip_blkid)) &&
 105                                    arg1->ip_posid == arg2->ip_posid);
 106 }
 107
 108 #ifdef NOT_USED
 109 Datum
 110 tidne(PG_FUNCTION_ARGS)
 111 {
 112         ItemPointer arg1 = PG_GETARG_ITEMPOINTER(0);
 113         ItemPointer arg2 = PG_GETARG_ITEMPOINTER(1);
 114
 115         PG_RETURN_BOOL(BlockIdGetBlockNumber(&(arg1->ip_blkid)) !=
 116                                    BlockIdGetBlockNumber(&(arg2->ip_blkid)) ||
 117                                    arg1->ip_posid != arg2->ip_posid);
 118 }
 119
 120 #endif
 121
 122 /*
 123  *      Functions to get latest tid of a specified tuple.
 124  *
 125  *      Maybe these implementations should be moved to another place
 126  */
 127
 128 static  ItemPointerData Current_last_tid = { {0, 0}, 0};
 129
 130 void
 131 setLastTid(const ItemPointer tid)
 132 {
 133         Current_last_tid = *tid;
 134 }
 135
 136 Datum
 137 currtid_byreloid(PG_FUNCTION_ARGS)
 138 {
 139         Oid                     reloid = PG_GETARG_OID(0);
 140         ItemPointer tid = PG_GETARG_ITEMPOINTER(1);
 141         ItemPointer result;
 142         Relation        rel;
 143
 144         result = (ItemPointer) palloc(sizeof(ItemPointerData));
 145         if (!reloid)
 146         {
 147                 *result = Current_last_tid;
 148                 PG_RETURN_ITEMPOINTER(result);
 149         }
 150         ItemPointerCopy(tid, result);
 151         if ((rel = heap_open(reloid, AccessShareLock)) != NULL)
 152         {
 153                 heap_get_latest_tid(rel, SnapshotNow, result);
 154                 heap_close(rel, AccessShareLock);
 155         }
 156         else
 157                 elog(ERROR, "Relation %u not found", reloid);
 158
 159         PG_RETURN_ITEMPOINTER(result);
 160 }
 161
 162 Datum
 163 currtid_byrelname(PG_FUNCTION_ARGS)
 164 {
 165         text       *relname = PG_GETARG_TEXT_P(0);
 166         ItemPointer tid = PG_GETARG_ITEMPOINTER(1);
 167         ItemPointer result;
 168         char       *str;
 169         Relation        rel;
 170
 171         str = DatumGetCString(DirectFunctionCall1(textout,
 172                                                                                           PointerGetDatum(relname)));
 173
 174         result = (ItemPointer) palloc(sizeof(ItemPointerData));
 175         ItemPointerCopy(tid, result);
 176         if ((rel = heap_openr(str, AccessShareLock)) != NULL)
 177         {
 178                 heap_get_latest_tid(rel, SnapshotNow, result);
 179                 heap_close(rel, AccessShareLock);
 180         }
 181         else
 182                 elog(ERROR, "Relation %s not found", str);
 183
 184         pfree(str);
 185
 186         PG_RETURN_ITEMPOINTER(result);
 187 }