Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1YBxaU-0002Vh-KM for pgsql-performance@arkaria.postgresql.org; Fri, 16 Jan 2015 03:28:42 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.80) (envelope-from ) id 1YBxaU-0003IC-5N for pgsql-performance@arkaria.postgresql.org; Fri, 16 Jan 2015 03:28:42 +0000 Received: from makus.postgresql.org ([2001:4800:1501:1::229]) by malur.postgresql.org with esmtps (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1YBxaS-0003I4-V5 for pgsql-performance@postgresql.org; Fri, 16 Jan 2015 03:28:41 +0000 Received: from mx-out.zmailcloud.com ([192.198.85.98] helo=mx-out-1.zmailcloud.com) by makus.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1YBxaP-0002zs-Kh for pgsql-performance@postgresql.org; Fri, 16 Jan 2015 03:28:39 +0000 Received: from smtp.01.com (smtp.01.com [10.10.0.43]) by mx-out-1.zmailcloud.com (Postfix) with ESMTP id 1040E564B4D; Thu, 15 Jan 2015 21:28:37 -0600 (CST) Received: from localhost (localhost [127.0.0.1]) by smtp-out-1.01.com (Postfix) with ESMTP id 07D3BA0422; Thu, 15 Jan 2015 21:28:37 -0600 (CST) X-Virus-Scanned: amavisd-new at smtp-out-1.01.com Received: from smtp.01.com ([127.0.0.1]) by localhost (smtp-out-1.01.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id QkZ3Mnus8STa; Thu, 15 Jan 2015 21:28:36 -0600 (CST) Received: from smtp.01.com (localhost [127.0.0.1]) by smtp-out-1.01.com (Postfix) with ESMTP id DC46CA0425; Thu, 15 Jan 2015 21:28:36 -0600 (CST) Received: from localhost (localhost [127.0.0.1]) by smtp-out-1.01.com (Postfix) with ESMTP id BEB90A0424; Thu, 15 Jan 2015 21:28:36 -0600 (CST) X-Virus-Scanned: amavisd-new at smtp-out-1.01.com Received: from smtp.01.com ([127.0.0.1]) by localhost (smtp-out-1.01.com [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id zBOxGzu0Jr6T; Thu, 15 Jan 2015 21:28:36 -0600 (CST) Received: from [172.24.244.13] (wireless-nat-23-linuxconf2015.auckland.ac.nz [130.216.30.134]) by smtp-out-1.01.com (Postfix) with ESMTPSA id 0BDBBA0422; Thu, 15 Jan 2015 21:28:35 -0600 (CST) Message-ID: <54B88562.4040500@agliodbs.com> Date: Fri, 16 Jan 2015 16:28:34 +1300 From: Josh Berkus Organization: PostgreSQL Experts Inc. User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: Mark Kirkwood , postgres performance list Subject: Re: Strange choice of general index over partial index References: <54B83F70.7080004@agliodbs.com> <54B85D32.7090106@catalyst.net.nz> <54B87820.3090101@catalyst.net.nz> <54B88032.7020206@catalyst.net.nz> <54B882B8.2050303@catalyst.net.nz> In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Pg-Spam-Score: -1.9 (-) 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 On 01/16/2015 04:17 PM, Mark Kirkwood wrote: > On 16/01/15 16:06, Mark Kirkwood wrote: > >> A bit more poking about shows that the major factor (which this fake >> dataset anyway) is the default for effective_cache_size (changes from >> 128MB to 4GB in 9.4). Increasing this makes 9.2 start using the >> files_in_flight index in a plain index scan too. >> > > Arrg - misread the planner output....in 9.2 what changes is a plan that > uses an index scan on the *file_state* index (not > files_in_flight)...which appears much faster than the bitmap scan on > file_state. Apologies for the confusion. > > I'm thinking that I'm seeing the effect Tom has just mentioned. It's not using a bitmapscan in either case; it's a straight indexscan. -- Josh Berkus PostgreSQL Experts Inc. http://pgexperts.com -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance