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Re: O_DIRECT setting

From: Mark Wong <markw(at)osdl(dot)org>
To: Guy Thornley <guy(at)esphion(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: O_DIRECT setting
Date: 2004-09-30 16:33:34
Message-ID: 20040930093334.C11282@osdl.org (view raw or flat)
Thread:
Lists: pgsql-performance
On Thu, Sep 30, 2004 at 07:02:32PM +1200, Guy Thornley wrote:
> Sorry about the belated reply, its been busy around here.
> 
> > > Incidentally, postgres heap files suffer really, really bad fragmentation,
> > > which affects sequential scan operations (VACUUM, ANALYZE, REINDEX ...)
> > > quite drastically. We have in-house patches that somewhat alleiviate this,
> > > but they are not release quality. Has anybody else suffered this?
> > > 
> > 
> > Any chance I could give those patches a try?  I'm interested in seeing
> > how they may affect our DBT-3 workload, which execute DSS type queries.
> 
> Like I said, the patches are not release quality... if you run them on a
> metadata journalling filesystem, without an 'ordered write' mode, its
> possible to end up with corrupt heaps after a crash because of garbage data
> in the extended files.
> 
> If/when we move to postgres 8 I'll try to ensure the patches get re-done
> with releasable quality
> 
> Guy Thornley

That's ok, we like to help test and proof things, we don't need patches to be
release quality.

Mark

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