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Re: seqscan for 100 out of 3M rows, index present - Mailing list pgsql-performance

From ktm@rice.edu
Subject Re: seqscan for 100 out of 3M rows, index present
Date
Msg-id 20130626204804.GC3264@aart.rice.edu
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In response to Re: seqscan for 100 out of 3M rows, index present  (Willy-Bas Loos <willybas@gmail.com>)
List pgsql-performance
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On Wed, Jun 26, 2013 at 10:36:10PM +0200, Willy-Bas Loos wrote:
> On Wed, Jun 26, 2013 at 10:31 PM, Jeff Janes <jeff.janes@gmail.com> wrote:
>
> >
> > Why is it retrieving 3.1 million, when it only needs 17?
> >
> >
> > that's because of the sequential scan, it reads all the data.
>
> cheers,
>
> willy-bas

Well, the two plans timings were pretty close together. Maybe your
cost model is off. Try adjusting the various cost parameters to
favor random I/O more.

Regards,
Ken

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