From: Scott Marlowe <scott.marlowe@gmail.com>
To: Frank Schoep <frank@ffnn.nl>
Cc: pgsql-performance@postgresql.org
Subject: Re: [Again] Postgres performance problem
Date: Wed, 12 Sep 2007 14:27:14 -0500
Message-ID: <dcc563d10709121227j523937d9v3e6cf7fe8b5236d8@mail.gmail.com> (raw)
In-Reply-To: <A9ADD88B-83D8-43FC-A58F-A7D2D38B9311@ffnn.nl>
References: <46E636CB.8080008@rentalia.com>
<43393.192.121.104.48.1189495883.squirrel@zigo.dhs.org>
<46E64891.9080005@rentalia.com>
<20070911225242.GG38801@decibel.org>
<46E79865.906@rentalia.com>
<dcc563d10709121128o1e5883a9n96b1f9ed74901be9@mail.gmail.com>
<2ca799770709121156l7ddbb20agf8086e8bfcbc881a@mail.gmail.com>
<dcc563d10709121207q66f09c33ldcd181e4a2876904@mail.gmail.com>
<A9ADD88B-83D8-43FC-A58F-A7D2D38B9311@ffnn.nl>
On 9/12/07, Frank Schoep <frank@ffnn.nl> wrote:
> On Sep 12, 2007, at 9:07 PM, Scott Marlowe wrote:
> > On 9/12/07, Mikko Partio <mpartio@gmail.com> wrote:
> >> …
> >> Aren't you mixing up REINDEX and CLUSTER?
> >
> > …
> > Either one does what a vacuum full did / does, but generally does
> > it better.
>
> On topic of REINDEX / VACUUM FULL versus a CLUSTER / VACUUM ANALYZE
> I'd like to ask if CLUSTER is safe to run on a table that is in
> active use.
>
> After updating my maintenance scripts from a VACUUM FULL (add me to
> the list) to CLUSTER (which improves performance a lot) I noticed I
> was getting "could not open relation …" errors in the log while the
> scripts ran so I reverted the change. This was on 8.1.9.
>
> Am I hitting a corner case or is it generally not a good idea to
> CLUSTER tables which are being queried? I haven't had problems with
> the REINDEX / VACUUM FULL combination while CLUSTER / VACUUM ANALYZE
> resulted in errors on the first run.
>
> Can the "could not open relation…" error bring down the whole
> database server? I'm really interested in using CLUSTER regularly as
> it speeds up my system by a factor of two because of more efficient I/O.
No, it won't bring it down. Basically the query lost the relation is
was operating against because it disappeared when the cluster command
runs.
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To: pgsql-performance@postgresql.org
Cc: scott.marlowe@gmail.com, frank@ffnn.nl
Subject: Re: [Again] Postgres performance problem
In-Reply-To: <dcc563d10709121227j523937d9v3e6cf7fe8b5236d8@mail.gmail.com>
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