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Implement prefetching via posix_fadvise() for bitmap index scans. A new

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GUC variable effective_io_concurrency controls how many concurrent block
prefetch requests will be issued.

(The best way to handle this for plain index scans is still under debate,
so that part is not applied yet --- tgl)

Greg Stark
This commit is contained in:
Tom Lane
2009-01-12 05:10:45 +00:00
parent 1a37056a74
commit b7b8f0b609
15 changed files with 422 additions and 17 deletions
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15
src/backend/storage/smgr/smgr.c
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@@ -11,7 +11,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/smgr/smgr.c,v 1.115 2009/01/01 17:23:48 momjian Exp $
* $PostgreSQL: pgsql/src/backend/storage/smgr/smgr.c,v 1.116 2009/01/12 05:10:44 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -48,6 +48,8 @@ typedef struct f_smgr
bool isRedo);
void (*smgr_extend) (SMgrRelation reln, ForkNumber forknum,
BlockNumber blocknum, char *buffer, bool isTemp);
void (*smgr_prefetch) (SMgrRelation reln, ForkNumber forknum,
BlockNumber blocknum);
void (*smgr_read) (SMgrRelation reln, ForkNumber forknum,
BlockNumber blocknum, char *buffer);
void (*smgr_write) (SMgrRelation reln, ForkNumber forknum,
@@ -65,7 +67,7 @@ typedef struct f_smgr
static const f_smgr smgrsw[] = {
/* magnetic disk */
{mdinit, NULL, mdclose, mdcreate, mdexists, mdunlink, mdextend,
mdread, mdwrite, mdnblocks, mdtruncate, mdimmedsync,
mdprefetch, mdread, mdwrite, mdnblocks, mdtruncate, mdimmedsync,
mdpreckpt, mdsync, mdpostckpt
}
};
@@ -375,6 +377,15 @@ smgrextend(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
buffer, isTemp);
}
/*
* smgrprefetch() -- Initiate asynchronous read of the specified block of a relation.
*/
void
smgrprefetch(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum)
{
(*(smgrsw[reln->smgr_which].smgr_prefetch)) (reln, forknum, blocknum);
}
/*
* smgrread() -- read a particular block from a relation into the supplied
* buffer.