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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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47
src/backend/commands/vacuum.c
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@@ -13,7 +13,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.377 2008/09/11 14:01:09 alvherre Exp $
* $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.378 2008/09/30 10:52:12 heikki Exp $
*
*-------------------------------------------------------------------------
*/
@@ -505,14 +505,6 @@ vacuum(VacuumStmt *vacstmt, Oid relid, bool do_toast,
* (autovacuum.c does this for itself.)
*/
vac_update_datfrozenxid();
/*
* If it was a database-wide VACUUM, print FSM usage statistics (we
* don't make you be superuser to see these). We suppress this in
* autovacuum, too.
*/
if (all_rels)
PrintFreeSpaceMapStatistics(elevel);
}
/*
@@ -1272,8 +1264,9 @@ full_vacuum_rel(Relation onerel, VacuumStmt *vacstmt)
}
}
/* update shared free space map with final free space info */
/* update thefree space map with final free space info, and vacuum it */
vac_update_fsm(onerel, &fraged_pages, vacrelstats->rel_pages);
FreeSpaceMapVacuum(onerel);
/* update statistics in pg_class */
vac_update_relstats(RelationGetRelid(onerel), vacrelstats->rel_pages,
@@ -2849,6 +2842,7 @@ repair_frag(VRelStats *vacrelstats, Relation onerel,
/* Truncate relation, if needed */
if (blkno < nblocks)
{
FreeSpaceMapTruncateRel(onerel, blkno);
RelationTruncate(onerel, blkno);
vacrelstats->rel_pages = blkno; /* set new number of blocks */
}
@@ -3243,6 +3237,7 @@ vacuum_heap(VRelStats *vacrelstats, Relation onerel, VacPageList vacuum_pages)
(errmsg("\"%s\": truncated %u to %u pages",
RelationGetRelationName(onerel),
vacrelstats->rel_pages, relblocks)));
FreeSpaceMapTruncateRel(onerel, relblocks);
RelationTruncate(onerel, relblocks);
vacrelstats->rel_pages = relblocks; /* set new number of blocks */
}
@@ -3475,8 +3470,8 @@ tid_reaped(ItemPointer itemptr, void *state)
}
/*
* Update the shared Free Space Map with the info we now have about
* free space in the relation, discarding any old info the map may have.
* Update the Free Space Map with the info we now have about free space in
* the relation.
*/
static void
vac_update_fsm(Relation onerel, VacPageList fraged_pages,
@@ -3484,26 +3479,8 @@ vac_update_fsm(Relation onerel, VacPageList fraged_pages,
{
int nPages = fraged_pages->num_pages;
VacPage *pagedesc = fraged_pages->pagedesc;
Size threshold;
FSMPageData *pageSpaces;
int outPages;
int i;
/*
* We only report pages with free space at least equal to the average
* request size --- this avoids cluttering FSM with uselessly-small bits
* of space. Although FSM would discard pages with little free space
* anyway, it's important to do this prefiltering because (a) it reduces
* the time spent holding the FSM lock in RecordRelationFreeSpace, and (b)
* FSM uses the number of pages reported as a statistic for guiding space
* management. If we didn't threshold our reports the same way
* vacuumlazy.c does, we'd be skewing that statistic.
*/
threshold = GetAvgFSMRequestSize(&onerel->rd_node);
pageSpaces = (FSMPageData *) palloc(nPages * sizeof(FSMPageData));
outPages = 0;
for (i = 0; i < nPages; i++)
{
/*
@@ -3514,17 +3491,9 @@ vac_update_fsm(Relation onerel, VacPageList fraged_pages,
if (pagedesc[i]->blkno >= rel_pages)
break;
if (pagedesc[i]->free >= threshold)
{
FSMPageSetPageNum(&pageSpaces[outPages], pagedesc[i]->blkno);
FSMPageSetSpace(&pageSpaces[outPages], pagedesc[i]->free);
outPages++;
}
RecordPageWithFreeSpace(onerel, pagedesc[i]->blkno, pagedesc[i]->free);
}
RecordRelationFreeSpace(&onerel->rd_node, outPages, outPages, pageSpaces);
pfree(pageSpaces);
}
/* Copy a VacPage structure */