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 1.29 2002/03/30 01:02:41 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 "catalog/namespace.h"
  23 #include "utils/builtins.h"
  24
  25 #define DatumGetItemPointer(X)   ((ItemPointer) DatumGetPointer(X))
  26 #define ItemPointerGetDatum(X)   PointerGetDatum(X)
  27 #define PG_GETARG_ITEMPOINTER(n) DatumGetItemPointer(PG_GETARG_DATUM(n))
  28 #define PG_RETURN_ITEMPOINTER(x) return ItemPointerGetDatum(x)
  29
  30 #define LDELIM                  '('
  31 #define RDELIM                  ')'
  32 #define DELIM                   ','
  33 #define NTIDARGS                2
  34
  35 /* ----------------------------------------------------------------
  36  *              tidin
  37  * ----------------------------------------------------------------
  38  */
  39 Datum
  40 tidin(PG_FUNCTION_ARGS)
  41 {
  42         char       *str = PG_GETARG_CSTRING(0);
  43         char       *p,
  44                            *coord[NTIDARGS];
  45         int                     i;
  46         ItemPointer result;
  47         BlockNumber blockNumber;
  48         OffsetNumber offsetNumber;
  49
  50         for (i = 0, p = str; *p && i < NTIDARGS && *p != RDELIM; p++)
  51                 if (*p == DELIM || (*p == LDELIM && !i))
  52                         coord[i++] = p + 1;
  53
  54         if (i < NTIDARGS)
  55                 elog(ERROR, "invalid tid format: '%s'", str);
  56
  57         blockNumber = (BlockNumber) atoi(coord[0]);
  58         offsetNumber = (OffsetNumber) atoi(coord[1]);
  59
  60         result = (ItemPointer) palloc(sizeof(ItemPointerData));
  61
  62         ItemPointerSet(result, blockNumber, offsetNumber);
  63
  64         PG_RETURN_ITEMPOINTER(result);
  65 }
  66
  67 /* ----------------------------------------------------------------
  68  *              tidout
  69  * ----------------------------------------------------------------
  70  */
  71 Datum
  72 tidout(PG_FUNCTION_ARGS)
  73 {
  74         ItemPointer itemPtr = PG_GETARG_ITEMPOINTER(0);
  75         BlockId         blockId;
  76         BlockNumber blockNumber;
  77         OffsetNumber offsetNumber;
  78         char            buf[32];
  79         static char *invalidTid = "()";
  80
  81         if (!ItemPointerIsValid(itemPtr))
  82                 PG_RETURN_CSTRING(pstrdup(invalidTid));
  83
  84         blockId = &(itemPtr->ip_blkid);
  85
  86         blockNumber = BlockIdGetBlockNumber(blockId);
  87         offsetNumber = itemPtr->ip_posid;
  88
  89         sprintf(buf, "(%d,%d)", (int) blockNumber, (int) offsetNumber);
  90
  91         PG_RETURN_CSTRING(pstrdup(buf));
  92 }
  93
  94 /*****************************************************************************
  95  *       PUBLIC ROUTINES                                                                                                                 *
  96  *****************************************************************************/
  97
  98 Datum
  99 tideq(PG_FUNCTION_ARGS)
 100 {
 101         ItemPointer arg1 = PG_GETARG_ITEMPOINTER(0);
 102         ItemPointer arg2 = PG_GETARG_ITEMPOINTER(1);
 103
 104         PG_RETURN_BOOL(BlockIdGetBlockNumber(&(arg1->ip_blkid)) ==
 105                                    BlockIdGetBlockNumber(&(arg2->ip_blkid)) &&
 106                                    arg1->ip_posid == arg2->ip_posid);
 107 }
 108
 109 #ifdef NOT_USED
 110 Datum
 111 tidne(PG_FUNCTION_ARGS)
 112 {
 113         ItemPointer arg1 = PG_GETARG_ITEMPOINTER(0);
 114         ItemPointer arg2 = PG_GETARG_ITEMPOINTER(1);
 115
 116         PG_RETURN_BOOL(BlockIdGetBlockNumber(&(arg1->ip_blkid)) !=
 117                                    BlockIdGetBlockNumber(&(arg2->ip_blkid)) ||
 118                                    arg1->ip_posid != arg2->ip_posid);
 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
 151         rel = heap_open(reloid, AccessShareLock);
 152
 153         ItemPointerCopy(tid, result);
 154         heap_get_latest_tid(rel, SnapshotNow, result);
 155
 156         heap_close(rel, AccessShareLock);
 157
 158         PG_RETURN_ITEMPOINTER(result);
 159 }
 160
 161 Datum
 162 currtid_byrelname(PG_FUNCTION_ARGS)
 163 {
 164         text       *relname = PG_GETARG_TEXT_P(0);
 165         ItemPointer tid = PG_GETARG_ITEMPOINTER(1);
 166         ItemPointer result;
 167         RangeVar   *relrv;
 168         Relation        rel;
 169
 170         relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname,
 171                                                                                                                 "currtid_byrelname"));
 172         rel = heap_openrv(relrv, AccessShareLock);
 173
 174         result = (ItemPointer) palloc(sizeof(ItemPointerData));
 175         ItemPointerCopy(tid, result);
 176
 177         heap_get_latest_tid(rel, SnapshotNow, result);
 178
 179         heap_close(rel, AccessShareLock);
 180
 181         PG_RETURN_ITEMPOINTER(result);
 182 }