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e5cf186277
The implementation of FSM for indexes is simpler than heap, where 0 is used to track if a page is in-use and (BLCKSZ - 1) if a page is free. One comment in indexfsm.c and one description in the documentation of pg_freespacemap were incorrect about that. Author: Alex Friedman <alexf01@gmail.com> Discussion: https://postgr.es/m/71eef655-c192-453f-ac45-2772fec2cb04@gmail.com Backpatch-through: 13
75 lines
1.7 KiB
C
75 lines
1.7 KiB
C
/*-------------------------------------------------------------------------
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*
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* indexfsm.c
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* POSTGRES free space map for quickly finding free pages in relations
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*
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*
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* Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* src/backend/storage/freespace/indexfsm.c
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*
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*
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* NOTES:
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*
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* This is similar to the FSM used for heap, in freespace.c, but instead
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* of tracking the amount of free space on pages, we only track whether
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* pages are completely free or in-use. We use the same FSM implementation
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* as for heaps, using 0 to denote used pages, and (BLCKSZ - 1) for unused.
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "storage/freespace.h"
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#include "storage/indexfsm.h"
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/*
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* Exported routines
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*/
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/*
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* GetFreeIndexPage - return a free page from the FSM
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*
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* As a side effect, the page is marked as used in the FSM.
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*/
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BlockNumber
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GetFreeIndexPage(Relation rel)
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{
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BlockNumber blkno = GetPageWithFreeSpace(rel, BLCKSZ / 2);
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if (blkno != InvalidBlockNumber)
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RecordUsedIndexPage(rel, blkno);
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return blkno;
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}
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/*
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* RecordFreeIndexPage - mark a page as free in the FSM
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*/
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void
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RecordFreeIndexPage(Relation rel, BlockNumber freeBlock)
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{
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RecordPageWithFreeSpace(rel, freeBlock, BLCKSZ - 1);
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}
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/*
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* RecordUsedIndexPage - mark a page as used in the FSM
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*/
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void
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RecordUsedIndexPage(Relation rel, BlockNumber usedBlock)
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{
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RecordPageWithFreeSpace(rel, usedBlock, 0);
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}
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/*
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* IndexFreeSpaceMapVacuum - scan and fix any inconsistencies in the FSM
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*/
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void
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IndexFreeSpaceMapVacuum(Relation rel)
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{
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FreeSpaceMapVacuum(rel);
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}
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