Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1Yaj8D-0004XY-UU for pgsql-admin@arkaria.postgresql.org; Wed, 25 Mar 2015 11:05:54 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.80) (envelope-from ) id 1Yaj8C-00051x-AD for pgsql-admin@arkaria.postgresql.org; Wed, 25 Mar 2015 11:05:52 +0000 Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29]) by malur.postgresql.org with esmtps (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1Yaj8B-00051k-6l for pgsql-admin@postgresql.org; Wed, 25 Mar 2015 11:05:51 +0000 Received: from plane.gmane.org ([80.91.229.3]) by magus.postgresql.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:256) (Exim 4.80) (envelope-from ) id 1Yaj81-0003YA-F9 for pgsql-admin@postgresql.org; Wed, 25 Mar 2015 11:05:49 +0000 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1Yaj7w-00082g-0H for pgsql-admin@postgresql.org; Wed, 25 Mar 2015 12:05:36 +0100 Received: from 185.40.248.10 ([185.40.248.10]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 25 Mar 2015 12:05:35 +0100 Received: from spam_eater by 185.40.248.10 with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 25 Mar 2015 12:05:35 +0100 X-Injected-Via-Gmane: http://gmane.org/ To: pgsql-admin@postgresql.org From: Thomas Kellerer Subject: Re: Postgres 9 : - How to interpret the EXPLAIN query results Date: Wed, 25 Mar 2015 12:05:28 +0100 Lines: 15 Message-ID: References: <80b319b3f6696a7f1672a4640f55e803@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: 185.40.248.10 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: <80b319b3f6696a7f1672a4640f55e803@mail.gmail.com> X-Pg-Spam-Score: 0.5 (/) List-Archive: List-Help: List-ID: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: X-Mailing-List: pgsql-admin Precedence: bulk Sender: pgsql-admin-owner@postgresql.org Khangelani Gama schrieb am 25.03.2015 um 11:28: > Thanks to all, but if this total cost is the total time it will take to retrieve the output then is it in minutes or milliseconds? > If it’s in milliseconds does it mean that it take about 213 hrs for a total of 768375132.77 No. The cost is not the total time. Quote from the manual measured in cost units that are arbitrary, but conventionally mean disk page fetches In general you can _assume_ that a query with a higher cost is likely to run longer than an equivalent query with lower costs. If you want the runtime of each step you need to use "explain (analyze)" - again this is documented in the manual. Thomas -- Sent via pgsql-admin mailing list (pgsql-admin@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-admin