Received: from makus.postgresql.org (makus.postgresql.org [98.129.198.125]) by mail.postgresql.org (Postfix) with ESMTP id 1B4E21F727DB for ; Thu, 9 Feb 2012 00:40:09 -0400 (AST) Received: from zql.com ([206.222.31.58]) by makus.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1RvLnj-0007gn-Iz for pgsql-performance@postgresql.org; Thu, 09 Feb 2012 04:40:08 +0000 Received: from localhost.localdomain ([127.0.0.1] helo=localhost) by zql.com with smtp (Exim 4.68) (envelope-from ) id 1RvLnS-0002pM-6Y; Wed, 08 Feb 2012 23:39:50 -0500 From: "Greg Sabino Mullane" To: pgsql-performance@postgresql.org Cc: Scott Marlowe , Josh Berkus , Marcos Ortiz Valmaseda CC: Scott Marlowe , Josh Berkus , Marcos Ortiz Valmaseda Subject: Re: random_page_cost = 2.0 on Heroku Postgres X-PGP-Key: 2529 DF6A B8F7 9407 E944 45B4 BC9B 9067 1496 4AC8 X-Request-PGP: http://www.biglumber.com/x/web?pk=2529DF6AB8F79407E94445B4BC9B906714964AC8 In-Reply-To: <4F3329DF.2060805@uci.cu> Date: Thu, 9 Feb 2012 04:39:50 -0000 X-Mailer: JoyMail 2.4.0 Message-ID: <00198dd656e4228cb66aa53a68ca0e14@biglumber.com> X-Pg-Spam-Score: -1.9 (-) X-Archive-Number: 201202/71 X-Sequence-Number: 46243 -----BEGIN PGP SIGNED MESSAGE----- Hash: RIPEMD160 > You can execute several queries with the three different values provided > by Scott and Josh. > - SET random_page_cost = 2.0 > First execution of the queries with EXPLAIN ANALYZE > - SET random_page_cost = 1.4 > Second execution of the queries with EXPLAIN ANALYZE > - SET random_page_cost = 1.2 > Second execution of the queries with EXPLAIN ANALYZE Well, such a tool would ideally be smarter than that, such that you would run EXPLAIN and compare to the previous plan and only run EXPLAIN ANALYZE if the plan changed. One could even decrement rpc slowly and find out at one points it changes, which would be more interesting than testing arbitrary numbers. Would lead to some really sweet graphs as well. :) - -- Greg Sabino Mullane greg@turnstep.com End Point Corporation http://www.endpoint.com/ PGP Key: 0x14964AC8 201202082338 http://biglumber.com/x/web?pk=2529DF6AB8F79407E94445B4BC9B906714964AC8 -----BEGIN PGP SIGNATURE----- iEYEAREDAAYFAk8zTewACgkQvJuQZxSWSsiprACfTlYKiC4SS1UnERU+1N/2EGhJ s9AAoIXLJk88hoNHEkWKhUTqikDBtC/B =S65l -----END PGP SIGNATURE-----