Received: from maia.hub.org (maia-3.hub.org [200.46.204.243]) by mail.postgresql.org (Postfix) with ESMTP id 6C3A51337BEF for ; Wed, 13 Apr 2011 17:16:45 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.243]) (amavisd-maia, port 10024) with ESMTP id 31707-01 for ; Wed, 13 Apr 2011 20:16:38 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from mail.gransy.com (mail.gransy.com [82.208.29.194]) by mail.postgresql.org (Postfix) with ESMTP id BED2D1337BE4 for ; Wed, 13 Apr 2011 17:16:37 -0300 (ADT) Received: from localhost (localhost [127.0.0.1]) by mail.gransy.com (Postfix) with ESMTP id D21022E5A0B1 for ; Wed, 13 Apr 2011 22:16:35 +0200 (CEST) Received: from mail.gransy.com ([127.0.0.1]) by localhost (nathalia.gransy.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id jnmTiAn09keY for ; Wed, 13 Apr 2011 22:16:35 +0200 (CEST) Received: from [192.168.1.221] (ip-94-112-0-189.net.upcbroadband.cz [94.112.0.189]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.gransy.com (Postfix) with ESMTPSA id BD1682E5A024 for ; Wed, 13 Apr 2011 22:16:35 +0200 (CEST) Message-ID: <4DA604A3.502@fuzzy.cz> Date: Wed, 13 Apr 2011 22:16:35 +0200 From: Tomas Vondra User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.13) Gecko/20101219 Lightning/1.0b3pre Thunderbird/3.1.7 MIME-Version: 1.0 To: pgsql-performance@postgresql.org Subject: Re: Slow query postgres 8.3 References: <945629628BB0174D86709AFE6D1CDEF5017A66C1@SP-EXCHMBC.sp.corp.collab.net> <50d8f2eb94b393c11221c9d5232d7326.squirrel@sq.gransy.com> <945629628BB0174D86709AFE6D1CDEF5017A66E3@SP-EXCHMBC.sp.corp.collab.net> <4DA2ED2F020000250003C657@gw.wicourts.gov> In-Reply-To: X-Enigmail-Version: 1.1.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-1.9 tagged_above=-10 required=5 tests=BAYES_00=-1.9 X-Spam-Level: X-Archive-Number: 201104/193 X-Sequence-Number: 43255 Dne 12.4.2011 09:33, Claudio Freire napsal(a): > I actually implemented a statistical system for measuring these kinds > of correlations. > > It's complex, but it might be adaptable to pgsql. Furthermore, one of > the latest projects of mine was to replace the purely statistical > approach with SVCs. You mean Support Vector Classifiers? Interesting idea, although I don't see how to apply that to query planning, especially with non-numeric inputs. Could you share more details on that statistical system and how do you think it could be applied in the pgsql world? > Too bad I won't be able to devote any time to that project before september. I've been working on cross column stats for some time, and although I had to put it aside for some time I'm going to devote more time to this issue soon. So interesting ideas/comments are very welcome. regards Tomas