| From: | Zeugswetter Andreas SB <ZeugswetterA(at)wien(dot)spardat(dot)at> |
|---|---|
| To: | "'Mikheev, Vadim'" <vmikheev(at)SECTORBASE(dot)COM>, "'Tom Lane'" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
| Cc: | Alfred Perlstein <bright(at)wintelcom(dot)net>, Tatsuo Ishii <t-ishii(at)sra(dot)co(dot)jp>, peter_e(at)gmx(dot)net, pgsql-hackers(at)postgresql(dot)org |
| Subject: | AW: RE: [COMMITTERS] pgsql/src/backend/access/transam ( xact.c xlog.c) |
| Date: | 2000-11-16 09:08:58 |
| Message-ID: | 11C1E6749A55D411A9670001FA687963368117@sdexcsrv1.f000.d0188.sd.spardat.at |
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| Lists: | pgsql-hackers |
> > Earlier, Vadim was talking about arranging to share fsyncs of the WAL
> > log file across transactions (after writing your commit record to the
> > log, sleep a few milliseconds to see if anyone else fsyncs before you
> > do; if not, issue the fsync yourself). That would offer less-than-
> > one-fsync-per-transaction performance without giving up any
> > guarantees.
> > If people feel a compulsion to have a tunable parameter, let 'em tune
> > the length of the pre-fsync sleep ...
>
> Already implemented (without ability to tune this parameter -
> xact.c:CommitDelay, - yet). Currently CommitDelay is 5, so
> backend sleeps 1/200 sec before checking/forcing log fsync.
Should definitely make that tuneable (per installation is imho sufficient),
no use in waiting if the dba knows there is only very little concurrency.
IIRC DB/2 defaults to not using this "commit pooling".
Andreas
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