Hi:
Just a hunch:
What about adding an index to the field
etapes_lignes_commandes(code_etape). Assuming your database
uses C locales. This might work for your particular query
since your filter is something like code_etape~~'COMP%'.
What about increasing the settings of work_mem, etc (check
http://www.powerpostgresql.com/PerfList) .
ludwig.
--- Philippe Lang <philippe.lang@attiksystem.ch> wrote:
> Hi,
>
> I have now disabled hyperthreading in /etc/grub.conf
> (added noht at the end
> of kernel lines), rebooted the server, run ANALYSE on the
> database again,
> and launched the query: things are even a little bit
> worse, it completes in
> 540 seconds now. So this is no ANALYSE or hyperthreading
> problem.
>
> Here are both EXPLAIN ANALYSE results, plus the query
> itself:
>
> Postgresql 7.4.5:
> http://www.attiksystem.ch/explain_analyze_74.txt
>
> Postgresql 8.1.4:
> http://www.attiksystem.ch/explain_analyze_81.txt
>
> Query is here: http://www.attiksystem.ch/big_query.txt
>
> The freebsd box, as far as I can remember, has not been
> specifically tuned.
> I did recompile a kernel with a few things inside, but
> really, I did not
> spend hours on that two years ago.
>
> Thanks,
>
> Philippe
>
>
> -----Message d'origine-----
> De : Tom Lane [mailto:tgl@sss.pgh.pa.us]
> Envoy�: mercredi, 31. mai 2006 16:39
> �: Philippe Lang
> Cc : pgsql-general@postgresql.org
> Objet : Re: [GENERAL] PGSQL 7.4 -> 8.1 migration &
> performance problem
>
> "Philippe Lang" <philippe.lang@attiksystem.ch> writes:
> > http://www.attiksystem.ch/postgresql-general.txt
>
> Please provide EXPLAIN ANALYZE, not just EXPLAIN, output
> ... and try to post
> it in an un-line-wrapped form.
>
> Also, as Ludwig mentioned, a common gotcha is to forget
> to ANALYZE your data
> after moving it to a new database.
>
> regards, tom lane
>
>
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