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@xxxxxxxxxxxxx] Envoyé : mercredi, 31. mai 2006 16:39 À : Philippe Lang Cc : pgsql-general@xxxxxxxxxxxxxx Objet : Re: [GENERAL] PGSQL 7.4 -> 8.1 migration & performance problem "Philippe Lang" <philippe.lang@xxxxxxxxxxxxxx> 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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