src/backend/storage/freespace/indexfsm.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * indexfsm.c
   4  *        POSTGRES free space map for quickly finding free pages in relations
   5  *
   6  *
   7  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
   8  * Portions Copyright (c) 1994, Regents of the University of California
   9  *
  10  * IDENTIFICATION
  11  *        $PostgreSQL$
  12  *
  13  *
  14  * NOTES:
  15  *
  16  *  This is similar to the FSM used for heap, in freespace.c, but instead
  17  *  of tracking the amount of free space on pages, we only track whether
  18  *  pages are completely free or in-use. We use the same FSM implementation
  19  *  as for heaps, using BLCKSZ - 1 to denote used pages, and 0 for unused.
  20  *
  21  *-------------------------------------------------------------------------
  22  */
  23 #include "postgres.h"
  24
  25 #include "storage/freespace.h"
  26 #include "storage/indexfsm.h"
  27 #include "storage/smgr.h"
  28
  29 /*
  30  * Exported routines
  31  */
  32
  33 /*
  34  * InitIndexFreeSpaceMap - Create or reset the FSM fork for relation.
  35  */
  36 void
  37 InitIndexFreeSpaceMap(Relation rel)
  38 {
  39         /* Create FSM fork if it doesn't exist yet, or truncate it if it does */
  40         RelationOpenSmgr(rel);
  41         if (!smgrexists(rel->rd_smgr, FSM_FORKNUM))
  42                 smgrcreate(rel->rd_smgr, FSM_FORKNUM, rel->rd_istemp, false);
  43         else
  44                 smgrtruncate(rel->rd_smgr, FSM_FORKNUM, 0, rel->rd_istemp);
  45 }
  46
  47 /*
  48  * GetFreeIndexPage - return a free page from the FSM
  49  *
  50  * As a side effect, the page is marked as used in the FSM.
  51  */
  52 BlockNumber
  53 GetFreeIndexPage(Relation rel)
  54 {
  55         BlockNumber blkno = GetPageWithFreeSpace(rel, BLCKSZ/2);
  56
  57         if (blkno != InvalidBlockNumber)
  58                 RecordUsedIndexPage(rel, blkno);
  59
  60         return blkno;
  61 }
  62
  63 /*
  64  * RecordFreeIndexPage - mark a page as free in the FSM
  65  */
  66 void
  67 RecordFreeIndexPage(Relation rel, BlockNumber freeBlock)
  68 {
  69         RecordPageWithFreeSpace(rel, freeBlock, BLCKSZ - 1);
  70 }
  71
  72
  73 /*
  74  * RecordUsedIndexPage - mark a page as used in the FSM
  75  */
  76 void
  77 RecordUsedIndexPage(Relation rel, BlockNumber usedBlock)
  78 {
  79         RecordPageWithFreeSpace(rel, usedBlock, 0);
  80 }
  81
  82 /*
  83  * IndexFreeSpaceMapTruncate - adjust for truncation of a relation.
  84  *
  85  * We need to delete any stored data past the new relation length, so that
  86  * we don't bogusly return removed block numbers.
  87  */
  88 void
  89 IndexFreeSpaceMapTruncate(Relation rel, BlockNumber nblocks)
  90 {
  91         FreeSpaceMapTruncateRel(rel, nblocks);
  92 }
  93
  94 /*
  95  * IndexFreeSpaceMapVacuum - scan and fix any inconsistencies in the FSM
  96  */
  97 void
  98 IndexFreeSpaceMapVacuum(Relation rel)
  99 {
 100         FreeSpaceMapVacuum(rel);
 101 }