Received: from makus.postgresql.org (makus.postgresql.org [98.129.198.125]) by mail.postgresql.org (Postfix) with ESMTP id BC931989B4E for ; Wed, 11 Jan 2012 11:40:49 -0400 (AST) Received: from sss.pgh.pa.us ([66.207.139.130]) by makus.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1Rl0I9-0005JX-HH for pgsql-sql@postgresql.org; Wed, 11 Jan 2012 15:40:49 +0000 Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.14.2/8.14.2) with ESMTP id q0BFeSpq020153; Wed, 11 Jan 2012 10:40:28 -0500 (EST) To: Gerardo Herzig cc: pgsql-sql@postgresql.org Subject: Re: amount of join's and sequential access to the tables involved In-reply-to: <1326296192.24629.12.camel@inca.fmed.uba.ar> References: <1326296192.24629.12.camel@inca.fmed.uba.ar> Comments: In-reply-to Gerardo Herzig message dated "Wed, 11 Jan 2012 12:36:32 -0300" Date: Wed, 11 Jan 2012 10:40:28 -0500 Message-ID: <20152.1326296428@sss.pgh.pa.us> From: Tom Lane X-Pg-Spam-Score: -1.9 (-) X-Archive-Number: 201201/38 X-Sequence-Number: 36209 Gerardo Herzig writes: > Hi all. Im working on a 'simple' query with 7, 8 left joins. After the > 9nth join or so, explain analyze became to show the plan with many > tables being read in sequential fashion. Of course, this slows down the > query response in a factor on 10. increase join_collapse_limit, perhaps? regards, tom lane