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Re: increasing shared buffer slow downs query performance. - Mailing list pgsql-performance

From Andreas Kretschmer
Subject Re: increasing shared buffer slow downs query performance.
Date
Msg-id 20080324100718.GA7822@KanotixBox
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In response to increasing shared buffer slow downs query performance.  ("petchimuthu lingam" <spmlingam@gmail.com>)
Responses Re: increasing shared buffer slow downs query performance.  ("Pavan Deolasee" <pavan.deolasee@gmail.com>)
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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
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