From: Alvaro Herrera <alvherre@commandprompt.com>
To: Scott Marlowe <scott.marlowe@gmail.com>
Cc: Mikko Partio <mpartio@gmail.com>
Cc: ruben@rentalia.com <ruben@rentalia.com>
Cc: Decibel! <decibel@decibel.org>
Cc: db@zigo.dhs.org
Cc: pgsql-performance@postgresql.org
Subject: Re: [Again] Postgres performance problem
Date: Wed, 12 Sep 2007 15:40:36 -0400
Message-ID: <20070912194036.GE2244@alvh.no-ip.org> (raw)
In-Reply-To: <dcc563d10709121207q66f09c33ldcd181e4a2876904@mail.gmail.com>
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>
Scott Marlowe escribió:
> > Aren't you mixing up REINDEX and CLUSTER?
>
> I don't think so. reindex (which runs on tables and indexes, so the
> name is a bit confusing, I admit) basically was originally a "repair"
> operation that rewrote the whole relation and wasn't completely
> transaction safe (way back, 7.2 days or so I think). Due to the
> issues with vacuum full bloating indexes, and being slowly replaced by
> regular vacuum, reindex received some attention to make it transaction
> / crash safe and has kind of take the place of vacuum full in terms of
> "how to fix bloated objects".
Hmm, REINDEX does not rewrite tables. If there are dead tuples, they
will still be there after REINDEX.
> cluster, otoh, rewrites the table into index order.
... excluding dead tuples, and then rewrites all the indexes.
--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.
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Cc: alvherre@commandprompt.com, scott.marlowe@gmail.com, mpartio@gmail.com, ruben@rentalia.com, decibel@decibel.org, db@zigo.dhs.org
Subject: Re: [Again] Postgres performance problem
In-Reply-To: <20070912194036.GE2244@alvh.no-ip.org>
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