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93 lines
2.3 KiB
93 lines
2.3 KiB
17 years ago
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/*-------------------------------------------------------------------------
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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) 1996-2008, 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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* $PostgreSQL: pgsql/src/backend/storage/freespace/indexfsm.c,v 1.1 2008/09/30 10:52:13 heikki Exp $
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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 BLCKSZ - 1 to denote used pages, and 0 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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#include "storage/smgr.h"
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/*
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* Exported routines
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*/
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/*
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* InitIndexFreeSpaceMap - Create or reset the FSM fork for relation.
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*/
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void
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InitIndexFreeSpaceMap(Relation rel)
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{
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/* Create FSM fork if it doesn't exist yet, or truncate it if it does */
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RelationOpenSmgr(rel);
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if (!smgrexists(rel->rd_smgr, FSM_FORKNUM))
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smgrcreate(rel->rd_smgr, FSM_FORKNUM, rel->rd_istemp, false);
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else
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smgrtruncate(rel->rd_smgr, FSM_FORKNUM, 0, rel->rd_istemp);
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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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* IndexFreeSpaceMapTruncate - adjust for truncation of a relation.
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*
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* We need to delete any stored data past the new relation length, so that
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* we don't bogusly return removed block numbers.
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*/
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void
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IndexFreeSpaceMapTruncate(Relation rel, BlockNumber nblocks)
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{
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FreeSpaceMapTruncateRel(rel, nblocks);
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}
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