Re: [Bizgres-general] WAL bypass for INSERT, UPDATE and

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Rick Gigger <rick(at)alpinenetworking(dot)com>
Cc: Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Martijn van Oosterhout <kleptog(at)svana(dot)org>, Greg Stark <gsstark(at)mit(dot)edu>, Rod Taylor <pg(at)rbt(dot)ca>, Qingqing Zhou <zhouqq(at)cs(dot)toronto(dot)edu>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: [Bizgres-general] WAL bypass for INSERT, UPDATE and
Date: 2006-02-07 04:13:59
Message-ID: 200602070413.k174DxY07346@candle.pha.pa.us
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Rick Gigger wrote:
> I was thinking the exact same thing. Except the "and just fsync()
> dirty pages on commit" part. Wouldn't that actually make the
> situation worse? I thought the whole point of WAL was that it was
> more efficient to fsync all of the changes in one sequential write in
> one file rather than fsyncing all of the separate dirty pages.

Uh, supposedly the WAL traffic is not as efficient as fsyncing whole
pages if you are doing lots of full pages.

---------------------------------------------------------------------------

>
> On Feb 6, 2006, at 7:24 PM, Christopher Kings-Lynne wrote:
>
> >> * Allow WAL logging to be turned off for a table, but the table
> >> might be dropped or truncated during crash recovery [walcontrol]
> >>
> >> Allow tables to bypass WAL writes and just fsync() dirty pages on
> >> commit. This should be implemented using ALTER TABLE, e.g. ALTER
> >> TABLE PERSISTENCE [ DROP | TRUNCATE | DEFAULT ]. Tables using
> >> non-default logging should not use referential integrity with
> >> default-logging tables. A table without dirty buffers during a
> >> crash could perhaps avoid the drop/truncate.
> >
> > This would be such a sweet feature for website session tables...
> >
> > Chris
> >
> >
> > ---------------------------(end of
> > broadcast)---------------------------
> > TIP 2: Don't 'kill -9' the postmaster
> >
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 4: Have you searched our list archives?
>
> http://archives.postgresql.org
>

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
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