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Rewrite the FSM. Instead of relying on a fixed-size shared memory segment, the

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free space information is stored in a dedicated FSM relation fork, with each
relation (except for hash indexes; they don't use FSM).

This eliminates the max_fsm_relations and max_fsm_pages GUC options; remove any
trace of them from the backend, initdb, and documentation.

Rewrite contrib/pg_freespacemap to match the new FSM implementation. Also
introduce a new variant of the get_raw_page(regclass, int4, int4) function in
contrib/pageinspect that let's you to return pages from any relation fork, and
a new fsm_page_contents() function to inspect the new FSM pages.
This commit is contained in:
Heikki Linnakangas
2008-09-30 10:52:14 +00:00
parent 2dbc0ca937
commit 15c121b3ed
53 changed files with 1844 additions and 2720 deletions
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92
src/backend/storage/freespace/indexfsm.c Normal file
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/*-------------------------------------------------------------------------
*
* indexfsm.c
* POSTGRES free space map for quickly finding free pages in relations
*
*
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/freespace/indexfsm.c,v 1.1 2008/09/30 10:52:13 heikki Exp $
*
*
* NOTES:
*
* This is similar to the FSM used for heap, in freespace.c, but instead
* of tracking the amount of free space on pages, we only track whether
* pages are completely free or in-use. We use the same FSM implementation
* as for heaps, using BLCKSZ - 1 to denote used pages, and 0 for unused.
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "storage/freespace.h"
#include "storage/indexfsm.h"
#include "storage/smgr.h"
/*
* Exported routines
*/
/*
* InitIndexFreeSpaceMap - Create or reset the FSM fork for relation.
*/
void
InitIndexFreeSpaceMap(Relation rel)
{
/* Create FSM fork if it doesn't exist yet, or truncate it if it does */
RelationOpenSmgr(rel);
if (!smgrexists(rel->rd_smgr, FSM_FORKNUM))
smgrcreate(rel->rd_smgr, FSM_FORKNUM, rel->rd_istemp, false);
else
smgrtruncate(rel->rd_smgr, FSM_FORKNUM, 0, rel->rd_istemp);
}
/*
* GetFreeIndexPage - return a free page from the FSM
*
* As a side effect, the page is marked as used in the FSM.
*/
BlockNumber
GetFreeIndexPage(Relation rel)
{
BlockNumber blkno = GetPageWithFreeSpace(rel, BLCKSZ/2);
if (blkno != InvalidBlockNumber)
RecordUsedIndexPage(rel, blkno);
return blkno;
}
/*
* RecordFreeIndexPage - mark a page as free in the FSM
*/
void
RecordFreeIndexPage(Relation rel, BlockNumber freeBlock)
{
RecordPageWithFreeSpace(rel, freeBlock, BLCKSZ - 1);
}
/*
* RecordUsedIndexPage - mark a page as used in the FSM
*/
void
RecordUsedIndexPage(Relation rel, BlockNumber usedBlock)
{
RecordPageWithFreeSpace(rel, usedBlock, 0);
}
/*
* IndexFreeSpaceMapTruncate - adjust for truncation of a relation.
*
* We need to delete any stored data past the new relation length, so that
* we don't bogusly return removed block numbers.
*/
void
IndexFreeSpaceMapTruncate(Relation rel, BlockNumber nblocks)
{
FreeSpaceMapTruncateRel(rel, nblocks);
}