Message-ID: <4EFB59BC.9000208@beccati.com>
Date: Wed, 28 Dec 2011 19:02:36 +0100
From: Matteo Beccati <php@beccati.com>
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To: Tom Lane <tgl@sss.pgh.pa.us>
CC: =?UTF-8?B?U8O2cmVuIE1leWVyLUVwcGxlcg==?= <soerenme@google.com>,
	pgsql-performance@postgresql.org
Subject: Re: PostgreSQL 9.0.4 blocking in lseek?
References: <4EA82B7C.1040008@google.com> <9398.1319761978@sss.pgh.pa.us>
	<4EFAE7F6.30603@beccati.com>
In-Reply-To: <4EFAE7F6.30603@beccati.com>
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Hi,

> A rather long import process is stuck since ~12hrs on a query that
> normally returns in a few seconds or minutes. Kust like to OP there's
> almost no activity on the box, only a single postgres process at 100% CPU.
> 
> Two separate queries, (although similar) have triggered the issue, and
> they are run one after another. Also, the import is also not always
> failing, I think it happened twice in about 10 runs. We're expected to
> go live in about two weeks so these were only test runs.
> 
> The explain looks like this:
> http://explain.depesz.com/s/TqD

The query eventually completed in more than 18h. For comparison a normal
run doesn't take more than 1m for that specific step.

Do you think that bad stats and suboptimal plan alone could explain such
a behaviour?


Cheers
-- 
Matteo Beccati

Development & Consulting - http://www.beccati.com/