Line data    Source code

       1              : /*-------------------------------------------------------------------------
       2              :  *
       3              :  * indexfsm.c
       4              :  *    POSTGRES free space map for quickly finding free pages in relations
       5              :  *
       6              :  *
       7              :  * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
       8              :  * Portions Copyright (c) 1994, Regents of the University of California
       9              :  *
      10              :  * IDENTIFICATION
      11              :  *    src/backend/storage/freespace/indexfsm.c
      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 0 to denote used pages, and (BLCKSZ - 1) for unused.
      20              :  *
      21              :  *-------------------------------------------------------------------------
      22              :  */
      23              : #include "postgres.h"
      24              : 
      25              : #include "storage/freespace.h"
      26              : #include "storage/indexfsm.h"
      27              : 
      28              : /*
      29              :  * Exported routines
      30              :  */
      31              : 
      32              : /*
      33              :  * GetFreeIndexPage - return a free page from the FSM
      34              :  *
      35              :  * As a side effect, the page is marked as used in the FSM.
      36              :  */
      37              : BlockNumber
      38        39886 : GetFreeIndexPage(Relation rel)
      39              : {
      40        39886 :     BlockNumber blkno = GetPageWithFreeSpace(rel, BLCKSZ / 2);
      41              : 
      42        39886 :     if (blkno != InvalidBlockNumber)
      43          277 :         RecordUsedIndexPage(rel, blkno);
      44              : 
      45        39886 :     return blkno;
      46              : }
      47              : 
      48              : /*
      49              :  * RecordFreeIndexPage - mark a page as free in the FSM
      50              :  */
      51              : void
      52         5310 : RecordFreeIndexPage(Relation rel, BlockNumber freeBlock)
      53              : {
      54         5310 :     RecordPageWithFreeSpace(rel, freeBlock, BLCKSZ - 1);
      55         5310 : }
      56              : 
      57              : 
      58              : /*
      59              :  * RecordUsedIndexPage - mark a page as used in the FSM
      60              :  */
      61              : void
      62          277 : RecordUsedIndexPage(Relation rel, BlockNumber usedBlock)
      63              : {
      64          277 :     RecordPageWithFreeSpace(rel, usedBlock, 0);
      65          277 : }
      66              : 
      67              : /*
      68              :  * IndexFreeSpaceMapVacuum - scan and fix any inconsistencies in the FSM
      69              :  */
      70              : void
      71          122 : IndexFreeSpaceMapVacuum(Relation rel)
      72              : {
      73          122 :     FreeSpaceMapVacuum(rel);
      74          122 : }