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Re: Forcing the right queryplan

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Maybe you can extract stuff like IP addresses and words like 'error'
and put it in a separate column in the table. Full text search is not
a solution for data that is in a wrong format.

On Fri, Sep 10, 2010 at 10:27 AM, Henk van Lingen <H.G.K.vanLingen@xxxxx> wrote:
> On Thu, Sep 09, 2010 at 11:16:36AM -0400, Tom Lane wrote:
>  > Henk van Lingen <H.G.K.vanLingen@xxxxx> writes:
>  > > On Thu, Sep 09, 2010 at 10:50:52AM -0400, Tom Lane wrote:
>  > >>>> Well, there's your problem: the planner is off by a factor of about 500
>  > >>>> on its estimate of the number of rows matching this query, and that's
>  > >>>> what's causing it to pick the wrong plan.  What you need to look into
>  > >>>> is getting that estimate to be more in sync with reality.  Probably
>  > >>>> increasing the stats target for the message column would help.
>  >
>  > >   But how can I get sane estimates for syslog data? Some searchstrings will
>  > >   result in only a few hits, others in thousands of records or more.
>  >
>  > That's what ANALYZE is for ...
>
>  Yes, off course. But I don't see how the most_common_vals & freqs and the
>  histogram_bounds for a text field with syslog data make any sense when
>  doing doing a search for a substring. Increasing the number of entries in
>  those stats lists doesn't make any sense also, i presume.
>
>  Those stats should be based on analysis of the to_tsvector index, to have
>  any meaning, i think.
>
>  Today I will look into the multicolumn index suggestion.
>
>  Regards,
>
> --
> Henk van Lingen, ICT-SC Netwerk & Telefonie,                  (o-      -+
> Universiteit Utrecht, Jenalaan 18a, room 0.12                 /\        |
> phone: +31-30-2538453                                         v_/_      |
> http://henk.vanlingen.net/             http://www.tuxtown.net/netiquette/
>
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