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) 1996-2000, PostgreSQL, Inc
   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 1.21 2000/07/05 23:11:35 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 LDELIM                  '('
  25 #define RDELIM                  ')'
  26 #define DELIM                   ','
  27 #define NTIDARGS                2
  28
  29 /* ----------------------------------------------------------------
  30  *              tidin
  31  * ----------------------------------------------------------------
  32  */
  33 ItemPointer
  34 tidin(const char *str)
  35 {
  36         const char *p,
  37                            *coord[NTIDARGS];
  38         int                     i;
  39         ItemPointer result;
  40
  41         BlockNumber blockNumber;
  42         OffsetNumber offsetNumber;
  43
  44         if (str == NULL)
  45                 return NULL;
  46
  47         for (i = 0, p = str; *p && i < NTIDARGS && *p != RDELIM; p++)
  48                 if (*p == DELIM || (*p == LDELIM && !i))
  49                         coord[i++] = p + 1;
  50
  51         /* if (i < NTIDARGS - 1) */
  52         if (i < NTIDARGS)
  53         {
  54                 elog(ERROR, "%s invalid tid format", str);
  55                 return NULL;
  56         }
  57
  58         blockNumber = (BlockNumber) atoi(coord[0]);
  59         offsetNumber = (OffsetNumber) atoi(coord[1]);
  60
  61         result = (ItemPointer) palloc(sizeof(ItemPointerData));
  62
  63         ItemPointerSet(result, blockNumber, offsetNumber);
  64
  65         return result;
  66 }
  67
  68 /* ----------------------------------------------------------------
  69  *              tidout
  70  * ----------------------------------------------------------------
  71  */
  72 char *
  73 tidout(ItemPointer itemPtr)
  74 {
  75         BlockNumber blockNumber;
  76         OffsetNumber offsetNumber;
  77         BlockId         blockId;
  78         char            buf[32];
  79         char       *str;
  80         static char *invalidTid = "()";
  81
  82         if (!itemPtr || !ItemPointerIsValid(itemPtr))
  83         {
  84                 str = palloc(strlen(invalidTid));
  85                 strcpy(str, invalidTid);
  86                 return str;
  87         }
  88
  89         blockId = &(itemPtr->ip_blkid);
  90
  91         blockNumber = BlockIdGetBlockNumber(blockId);
  92         offsetNumber = itemPtr->ip_posid;
  93
  94         sprintf(buf, "(%d,%d)", blockNumber, offsetNumber);
  95
  96         str = (char *) palloc(strlen(buf) + 1);
  97         strcpy(str, buf);
  98
  99         return str;
 100 }
 101
 102 /*****************************************************************************
 103  *       PUBLIC ROUTINES                                                                                                                 *
 104  *****************************************************************************/
 105
 106 bool
 107 tideq(ItemPointer arg1, ItemPointer arg2)
 108 {
 109         if ((!arg1) || (!arg2))
 110                 return false;
 111
 112         return (BlockIdGetBlockNumber(&(arg1->ip_blkid)) ==
 113                         BlockIdGetBlockNumber(&(arg2->ip_blkid)) &&
 114                         arg1->ip_posid == arg2->ip_posid);
 115 }
 116
 117 #ifdef NOT_USED
 118 bool
 119 tidne(ItemPointer arg1, ItemPointer arg2)
 120 {
 121         if ((!arg1) || (!arg2))
 122                 return false;
 123         return (BlockIdGetBlockNumber(&(arg1->ip_blkid)) !=
 124                         BlockIdGetBlockNumber(&(arg2->ip_blkid)) ||
 125                         arg1->ip_posid != arg2->ip_posid);
 126 }
 127 #endif
 128
 129 /*
 130  *      Functions to get latest tid of a specified tuple.
 131  *
 132  *      Maybe these implementations should be moved to another place
 133  */
 134 Datum
 135 currtid_byreloid(PG_FUNCTION_ARGS)
 136 {
 137         Oid                             reloid = PG_GETARG_OID(0);
 138         ItemPointer             tid = (ItemPointer) PG_GETARG_POINTER(1);
 139         ItemPointer             result,
 140                                         ret;
 141         Relation                rel;
 142
 143         result = (ItemPointer) palloc(sizeof(ItemPointerData));
 144         ItemPointerSetInvalid(result);
 145         if ((rel = heap_open(reloid, AccessShareLock)) != NULL)
 146         {
 147                 ret = heap_get_latest_tid(rel, SnapshotNow, tid);
 148                 if (ret)
 149                         ItemPointerCopy(ret, result);
 150                 heap_close(rel, AccessShareLock);
 151         }
 152         else
 153                 elog(ERROR, "Relation %u not found", reloid);
 154
 155         PG_RETURN_POINTER(result);
 156 }
 157
 158 Datum
 159 currtid_byrelname(PG_FUNCTION_ARGS)
 160 {
 161         text               *relname = PG_GETARG_TEXT_P(0);
 162         ItemPointer             tid = (ItemPointer) PG_GETARG_POINTER(1);
 163         ItemPointer             result,
 164                                         ret;
 165         char               *str;
 166         Relation                rel;
 167
 168         str = DatumGetCString(DirectFunctionCall1(textout,
 169                                                                                           PointerGetDatum(relname)));
 170
 171         result = (ItemPointer) palloc(sizeof(ItemPointerData));
 172         ItemPointerSetInvalid(result);
 173         if ((rel = heap_openr(str, AccessShareLock)) != NULL)
 174         {
 175                 ret = heap_get_latest_tid(rel, SnapshotNow, tid);
 176                 if (ret)
 177                         ItemPointerCopy(ret, result);
 178                 heap_close(rel, AccessShareLock);
 179         }
 180         else
 181                 elog(ERROR, "Relation %s not found", str);
 182
 183         pfree(str);
 184
 185         PG_RETURN_POINTER(result);
 186 }