Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1YvVcJ-0000lV-KD for pgsql-performance@arkaria.postgresql.org; Thu, 21 May 2015 18:54:51 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.80) (envelope-from ) id 1YvVcJ-0007Sg-5H for pgsql-performance@arkaria.postgresql.org; Thu, 21 May 2015 18:54:51 +0000 Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29]) by malur.postgresql.org with esmtps (TLS1.2:RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1YvVcI-0007Sa-DB for pgsql-performance@postgresql.org; Thu, 21 May 2015 18:54:50 +0000 Received: from mx-out.zmailcloud.com ([192.198.85.98] helo=mx-out-1.zmailcloud.com) by magus.postgresql.org with esmtp (Exim 4.84) (envelope-from ) id 1YvVcE-00037N-QH for pgsql-performance@postgresql.org; Thu, 21 May 2015 18:54:49 +0000 Received: from smtp.01.com (smtp.01.com [10.10.0.43]) by mx-out-1.zmailcloud.com (Postfix) with ESMTP id 1E62056408E; Thu, 21 May 2015 13:54:45 -0500 (CDT) Received: from localhost (localhost [127.0.0.1]) by smtp-out-2.01.com (Postfix) with ESMTP id 0C8EA60256; Thu, 21 May 2015 13:54:45 -0500 (CDT) X-Virus-Scanned: amavisd-new at smtp-out-2.01.com Received: from smtp.01.com ([127.0.0.1]) by localhost (smtp-out-2.01.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 3Hkn2AAMdFN6; Thu, 21 May 2015 13:54:44 -0500 (CDT) Received: from smtp.01.com (localhost [127.0.0.1]) by smtp-out-2.01.com (Postfix) with ESMTP id DD2CA6025C; Thu, 21 May 2015 13:54:44 -0500 (CDT) Received: from localhost (localhost [127.0.0.1]) by smtp-out-2.01.com (Postfix) with ESMTP id C6B046025B; Thu, 21 May 2015 13:54:44 -0500 (CDT) X-Virus-Scanned: amavisd-new at smtp-out-2.01.com Received: from smtp.01.com ([127.0.0.1]) by localhost (smtp-out-2.01.com [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id bN4buDd0ujo1; Thu, 21 May 2015 13:54:44 -0500 (CDT) Received: from [172.47.23.103] (50-0-190-244.dsl.dynamic.fusionbroadband.com [50.0.190.244]) by smtp-out-2.01.com (Postfix) with ESMTPSA id 4B87C60256; Thu, 21 May 2015 13:54:44 -0500 (CDT) Message-ID: <555E29F0.5030907@agliodbs.com> Date: Thu, 21 May 2015 11:54:40 -0700 From: Josh Berkus Organization: PostgreSQL Experts Inc. User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: Jan Gunnar Dyrset , "pgsql-performance@postgresql.org" Subject: Re: PostgreSQL disk fragmentation causes performance problems on Windows References: In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Pg-Spam-Score: -3.0 (---) 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 04/23/2015 12:47 PM, Jan Gunnar Dyrset wrote: > I think that preallocating lumps of a given, configurable size, say 4 > MB, for the tables would remove this problem. The max number of > fragments on a 1 GB file would then be 250, which is no problem. Is > this possible to configure in PostgreSQL? If not, how difficult is it to > implement in the database? It is not currently possible to configure. This has been talked about as a feature, but would require major work on PostgreSQL to make it possible. You'd be looking at several months of effort by a really good hacker, and then a whole bunch of performance testing. If you have the budget for this, then please let's talk about it because right now nobody is working on it. Note that this could be a dead end; it's possible that preallocating large extents could cause worse problems than the current fragmentation issues. -- 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