| From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | Ragnar Kjørstad <postgres(at)ragnark(dot)vestdata(dot)no> |
| Cc: | Gaetano Mendola <mendola(at)bigfoot(dot)com>, pgsql-admin(at)postgresql(dot)org |
| Subject: | Re: fsync or fdatasync |
| Date: | 2002-09-10 17:17:56 |
| Message-ID: | 200209101717.g8AHHuV29296@candle.pha.pa.us |
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| Lists: | pgsql-admin |
Ragnar Kjrstad wrote:
> On Tue, Sep 10, 2002 at 11:40:24AM -0400, Bruce Momjian wrote:
> >
> > The original poster was wrong about the default.
> >
> > We use fdatasync where available, and fsync when it is not.
>
> Makes sense.
>
> > We also use
> > O_SYNC on open if it is available.
>
> Why? That will slow tings down...
Actually, no, we are only O_SYNC'ing the WAL writes and sometimes that
is faster because you are not writing then fsyncing, you are just
writing. The fdatasync only is better than O_SYNC when you are doing
multiple WAL writes before an fdatasync and we normally don't do that.
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
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