Received: from maia.hub.org (maia-3.hub.org [200.46.204.243]) by mail.postgresql.org (Postfix) with ESMTP id D54DA1337B49 for ; Fri, 18 Mar 2011 08:14:26 -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 50242-02 for ; Fri, 18 Mar 2011 11:14:19 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from lo.gmane.org (lo.gmane.org [80.91.229.12]) by mail.postgresql.org (Postfix) with ESMTP id 06E021337B43 for ; Fri, 18 Mar 2011 08:14:18 -0300 (ADT) Received: from list by lo.gmane.org with local (Exim 4.69) (envelope-from ) id 1Q0XdJ-0006Cd-7J for pgsql-performance@postgresql.org; Fri, 18 Mar 2011 12:14:17 +0100 Received: from 217.110.94.67 ([217.110.94.67]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 18 Mar 2011 12:14:17 +0100 Received: from spam_eater by 217.110.94.67 with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 18 Mar 2011 12:14:17 +0100 X-Injected-Via-Gmane: http://gmane.org/ To: pgsql-performance@postgresql.org From: Thomas Kellerer Subject: Re: Disabling nested loops - worst case performance Date: Fri, 18 Mar 2011 12:14:05 +0100 Lines: 15 Message-ID: References: <4D8306A7.7020205@thl.fi> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Complaints-To: usenet@dough.gmane.org X-Gmane-NNTP-Posting-Host: 217.110.94.67 User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.23) Gecko/20090812 Thunderbird/2.0.0.23 Mnenhy/0.7.6.666 In-Reply-To: <4D8306A7.7020205@thl.fi> X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-0.735 tagged_above=-10 required=5 tests=BAYES_00=-1.9, FREEMAIL_FROM=0.001, RCVD_NUMERIC_HELO=1.164, T_RP_MATCHES_RCVD=-0.01, T_TO_NO_BRKTS_FREEMAIL=0.01 X-Spam-Level: X-Archive-Number: 201103/209 X-Sequence-Number: 42888 Anssi Kääriäinen, 18.03.2011 08:15: > Hello list, > > I am working on a Entity-Attribute-Value (EAV) database using > PostgreSQL 8.4.7. The basic problem is that when joining multiple > times different entities the planner thinks that there is vastly less > rows to join than there is in reality and decides to use multiple > nested loops for the join chain. Did you consider using hstore instead? I think in the PostgreSQL world, this is a better alternative than EAV and most probably faster as well. Regards Thomas