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) 1996-2009, 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  * GetFreeIndexPage - return a free page from the FSM
  35  *
  36  * As a side effect, the page is marked as used in the FSM.
  37  */
  38 BlockNumber
  39 GetFreeIndexPage(Relation rel)
  40 {
  41         BlockNumber blkno = GetPageWithFreeSpace(rel, BLCKSZ / 2);
  42
  43         if (blkno != InvalidBlockNumber)
  44                 RecordUsedIndexPage(rel, blkno);
  45
  46         return blkno;
  47 }
  48
  49 /*
  50  * RecordFreeIndexPage - mark a page as free in the FSM
  51  */
  52 void
  53 RecordFreeIndexPage(Relation rel, BlockNumber freeBlock)
  54 {
  55         RecordPageWithFreeSpace(rel, freeBlock, BLCKSZ - 1);
  56 }
  57
  58
  59 /*
  60  * RecordUsedIndexPage - mark a page as used in the FSM
  61  */
  62 void
  63 RecordUsedIndexPage(Relation rel, BlockNumber usedBlock)
  64 {
  65         RecordPageWithFreeSpace(rel, usedBlock, 0);
  66 }
  67
  68 /*
  69  * IndexFreeSpaceMapVacuum - scan and fix any inconsistencies in the FSM
  70  */
  71 void
  72 IndexFreeSpaceMapVacuum(Relation rel)
  73 {
  74         FreeSpaceMapVacuum(rel);
  75 }