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Remove unnecessary calls of FlushRelationBuffers: there is no need

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to write out data that we are about to tell the filesystem to drop.
smgr_internal_unlink already had a DropRelFileNodeBuffers call to
get rid of dead buffers without a write after it's no longer possible
to roll back the deleting transaction.  Adding a similar call in
smgrtruncate simplifies callers and makes the overall division of
labor clearer.  This patch removes the former behavior that VACUUM
would write all dirty buffers of a relation unconditionally.
This commit is contained in:
Tom Lane
2005-03-20 22:00:54 +00:00
parent 683f60da3d
commit 354049c709
10 changed files with 91 additions and 236 deletions
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38
src/backend/commands/vacuum.c
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@@ -13,7 +13,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.304 2005/03/16 21:38:05 tgl Exp $
* $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.305 2005/03/20 22:00:52 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -1138,16 +1138,6 @@ full_vacuum_rel(Relation onerel, VacuumStmt *vacstmt)
/* Clean pages from vacuum_pages list */
vacuum_heap(vacrelstats, onerel, &vacuum_pages);
}
else
{
/*
* Flush dirty pages out to disk. We must do this even if we
* didn't do anything else, because we want to ensure that all
* tuples have correct on-row commit status on disk (see
* bufmgr.c's comments for FlushRelationBuffers()).
*/
FlushRelationBuffers(onerel, vacrelstats->rel_pages);
}
}
/* update shared free space map with final free space info */
@@ -2420,15 +2410,7 @@ repair_frag(VRelStats *vacrelstats, Relation onerel,
pfree(Nvacpagelist.pagedesc);
}
/*
* Flush dirty pages out to disk. We do this unconditionally, even if
* we don't need to truncate, because we want to ensure that all
* tuples have correct on-row commit status on disk (see bufmgr.c's
* comments for FlushRelationBuffers()).
*/
FlushRelationBuffers(onerel, blkno);
/* truncate relation, if needed */
/* Truncate relation, if needed */
if (blkno < nblocks)
{
RelationTruncate(onerel, blkno);
@@ -2818,27 +2800,17 @@ vacuum_heap(VRelStats *vacrelstats, Relation onerel, VacPageList vacuum_pages)
}
}
/*
* Flush dirty pages out to disk. We do this unconditionally, even if
* we don't need to truncate, because we want to ensure that all
* tuples have correct on-row commit status on disk (see bufmgr.c's
* comments for FlushRelationBuffers()).
*/
/* Truncate relation if there are some empty end-pages */
Assert(vacrelstats->rel_pages >= vacuum_pages->empty_end_pages);
relblocks = vacrelstats->rel_pages - vacuum_pages->empty_end_pages;
FlushRelationBuffers(onerel, relblocks);
/* truncate relation if there are some empty end-pages */
if (vacuum_pages->empty_end_pages > 0)
{
relblocks = vacrelstats->rel_pages - vacuum_pages->empty_end_pages;
ereport(elevel,
(errmsg("\"%s\": truncated %u to %u pages",
RelationGetRelationName(onerel),
vacrelstats->rel_pages, relblocks)));
RelationTruncate(onerel, relblocks);
vacrelstats->rel_pages = relblocks; /* set new number of
* blocks */
vacrelstats->rel_pages = relblocks; /* set new number of blocks */
}
}