Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1XZ0MB-0006fe-AJ for pgsql-performance@arkaria.postgresql.org; Tue, 30 Sep 2014 16:32:55 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.80) (envelope-from ) id 1XZ0MA-0002Zi-HR for pgsql-performance@arkaria.postgresql.org; Tue, 30 Sep 2014 16:32:54 +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 1XZ0M9-0002Za-C3 for pgsql-performance@postgresql.org; Tue, 30 Sep 2014 16:32:53 +0000 Received: from sss.pgh.pa.us ([66.207.139.130]) by magus.postgresql.org with esmtps (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1XZ0M5-0001Yc-8F for pgsql-performance@postgresql.org; Tue, 30 Sep 2014 16:32:52 +0000 Received: from sss1.sss.pgh.pa.us (localhost [127.0.0.1]) by sss.pgh.pa.us (8.14.4/8.14.4) with ESMTP id s8UGWb1P010322; Tue, 30 Sep 2014 12:32:37 -0400 From: Tom Lane To: "Graeme B. Bell" cc: Simon Riggs , Merlin Moncure , "Josh Berkus" , postgres performance list Subject: Re: Yet another abort-early plan disaster on 9.3 In-reply-to: <9E62E5EE-3E0E-4871-84B4-34E82E1C8AC9@skogoglandskap.no> References: <541A2335.3060100@agliodbs.com> <541C7891.7000902@agliodbs.com> <541DC87F.3030800@agliodbs.com> <5420B71C.6010208@agliodbs.com> <13982.1412031637@sss.pgh.pa.us> <9E62E5EE-3E0E-4871-84B4-34E82E1C8AC9@skogoglandskap.no> Comments: In-reply-to "Graeme B. Bell" message dated "Tue, 30 Sep 2014 11:34:48 -0000" Date: Tue, 30 Sep 2014 12:32:37 -0400 Message-ID: <10321.1412094757@sss.pgh.pa.us> X-Pg-Spam-Score: -2.6 (--) List-Archive: List-Help: List-ID: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: X-Mailing-List: pgsql-performance Precedence: bulk Sender: pgsql-performance-owner@postgresql.org "Graeme B. Bell" writes: > Every year or two the core count goes up. Can/should/does postgres ever attempt two strategies in parallel, in cases where strategy A is generally good but strategy B prevents bad worst case behaviour? Kind of like a Schrödinger's Cat approach to scheduling. What problems would it raise? You can't run two plans and have them both returning rows to the client, or performing inserts/updates/deletes as the case may be. regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance