Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA384:256) (Exim 4.89) (envelope-from ) id 1ezRBq-0006ja-2N for pgsql-performance@arkaria.postgresql.org; Fri, 23 Mar 2018 18:13:22 +0000 Received: from localhost ([127.0.0.1] helo=malur.postgresql.org) by malur.postgresql.org with esmtp (Exim 4.89) (envelope-from ) id 1ezRBp-0003Tu-30 for pgsql-performance@arkaria.postgresql.org; Fri, 23 Mar 2018 18:13:21 +0000 Received: from makus.postgresql.org ([2001:4800:1501:1::229]) by malur.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA384:256) (Exim 4.89) (envelope-from ) id 1ezRBo-0003Te-Oo for pgsql-performance@lists.postgresql.org; Fri, 23 Mar 2018 18:13:20 +0000 Received: from uucp.dinoex.sub.de ([2001:1440:5001:1::2]) by makus.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA384:256) (Exim 4.89) (envelope-from ) id 1ezRBl-0002JF-5I for pgsql-performance@lists.postgresql.org; Fri, 23 Mar 2018 18:13:19 +0000 Received: from uucp.dinoex.sub.de (uucp.dinoex.sub.de [194.45.71.2]) by uucp.dinoex.sub.de (8.15.2/8.15.2) with ESMTPS id w2NID3fR087882 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Fri, 23 Mar 2018 19:13:04 +0100 (CET) (envelope-from pmc@citylink.dinoex.sub.org) Received: from citylink.dinoex.sub.org (uucp@localhost) by uucp.dinoex.sub.de (8.15.2/8.15.2/Submit) with UUCP id w2NID3vY087881; Fri, 23 Mar 2018 19:13:03 +0100 (CET) (envelope-from pmc@citylink.dinoex.sub.org) Received: from gate.oper.dinoex.org (gate-e [192.168.98.2]) by citylink.dinoex.sub.de (8.15.2/8.15.2) with ESMTP id w2NHdKj9058918; Fri, 23 Mar 2018 18:39:20 +0100 (CET) (envelope-from peter@gate.oper.dinoex.org) Received: from gate.oper.dinoex.org (gate-e [192.168.98.2]) by gate.oper.dinoex.org (8.15.2/8.15.2) with ESMTP id w2NHawB3058589; Fri, 23 Mar 2018 18:36:59 +0100 (CET) (envelope-from peter@gate.oper.dinoex.org) Received: (from peter@localhost) by gate.oper.dinoex.org (8.15.2/8.15.2/Submit) id w2NHawWn058588; Fri, 23 Mar 2018 18:36:58 +0100 (CET) (envelope-from peter) Date: Fri, 23 Mar 2018 18:36:58 +0100 From: Peter To: Tom Lane Cc: Laurenz Albe , pgsql-performance@lists.postgresql.org Subject: Re: Should from_collapse be switched off? (queries 10 times faster) Message-ID: <20180323173658.GA58069@gate.oper.dinoex.org> References: <20180323100308.GA1188@gate.oper.dinoex.org> <1521805295.2471.40.camel@cybertec.at> <18405.1521814459@sss.pgh.pa.us> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <18405.1521814459@sss.pgh.pa.us> User-Agent: Mutt/1.8.3 (2017-05-23) X-Milter: Spamilter (Reciever: uucp.dinoex.sub.de; Sender-ip: 194.45.71.2; Sender-helo: uucp.dinoex.sub.de;) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (uucp.dinoex.sub.de [194.45.71.2]); Fri, 23 Mar 2018 19:13:05 +0100 (CET) List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Precedence: bulk On Fri, Mar 23, 2018 at 10:14:19AM -0400, Tom Lane wrote: ! It's conceivable that the OP's problem is actually planning time ! (if the query joins sufficiently many tables) and that restricting ! the cost of the join plan search is really what he needs to do. Negative. Plnning time 10 to 27 ms. Execution time 600 to 6300 ms. ! Lacking any further information about the problem, we can't say. ! We can, however, point to ! https://wiki.postgresql.org/wiki/Slow_Query_Questions ! concerning how to ask this type of question effectively. I strongly hope the data that I sent as followup will now suffice Your expectations. rgds, PMc