From: Andreas Kretschmer <akretschmer@spamfence.net>
To: pgsql-performance@postgresql.org
Subject: Re: increasing shared buffer slow downs query performance.
Date: Mon, 24 Mar 2008 11:07:19 +0100
Message-ID: <20080324100718.GA7822@KanotixBox> (raw)
In-Reply-To: <cd233fc30803240227u7507f0c7wf67bb313c61f8a7@mail.gmail.com>
References: <cd233fc30803240227u7507f0c7wf67bb313c61f8a7@mail.gmail.com>
petchimuthu lingam <spmlingam@gmail.com> schrieb:
> Hi friends,
>
> I am using postgresql 8.1, I have shared_buffers = 50000, now i execute the
> query, it takes 18 seconds to do sequential scan, when i reduced to 5000, it
> takes one 10 seconds, Why.
Wild guess: the second time the data are in the filesystem cache.
>
> Can anyone explain what is the reason, ( any other configuration is needed in
> postgresql.conf)
Show us the EXPLAIN ANALYSE - Output.
Andreas
--
Really, I'm not out to destroy Microsoft. That will just be a completely
unintentional side effect. (Linus Torvalds)
"If I was god, I would recompile penguin with --enable-fly." (unknow)
Kaufbach, Saxony, Germany, Europe. N 51.05082°, E 13.56889°
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To: pgsql-performance@postgresql.org
Cc: akretschmer@spamfence.net
Subject: Re: increasing shared buffer slow downs query performance.
In-Reply-To: <20080324100718.GA7822@KanotixBox>
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