Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1VwaFe-0000N5-Pc for pgsql-performance@arkaria.postgresql.org; Fri, 27 Dec 2013 16:27:06 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.80) (envelope-from ) id 1VwaFe-0007Xn-9R for pgsql-performance@arkaria.postgresql.org; Fri, 27 Dec 2013 16:27:06 +0000 Received: from makus.postgresql.org ([2001:4800:7903:4::125]) by malur.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1VwaFd-0007Xh-E5 for pgsql-performance@postgresql.org; Fri, 27 Dec 2013 16:27:05 +0000 Received: from kilimanjaro.scorpionshops.com ([82.118.24.202]) by makus.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1VwaFa-0000Az-BV for pgsql-performance@postgresql.org; Fri, 27 Dec 2013 16:27:04 +0000 Received: from [92.32.205.123] (92-32-205-123.tn.glocalnet.net [92.32.205.123]) by kilimanjaro.scorpionshops.com (Postfix) with ESMTPSA id A37247BC0D2; Fri, 27 Dec 2013 17:27:00 +0100 (CET) Message-ID: <52BDAA62.9000600@proxel.se> Date: Fri, 27 Dec 2013 17:27:14 +0100 From: Andreas Karlsson User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20131005 Icedove/17.0.9 MIME-Version: 1.0 To: GR Vishwanath CC: pgsql-performance@postgresql.org Subject: Re: Does fsync on/off for wal AND Checkpoint? References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed 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 12/27/2013 04:55 PM, GR Vishwanath wrote: > Is fscnc off/on pertain only to writing WAL buffers to disk? > > Or is that also relevant to writing of dirty buffers to disk > (checkpoint/bg)? > > Curious because in the docs fsync on/off is mentioned under WAL > configuration. Further there is a wal_sync_method but not a > "checkpoint_sync_method". The setting is for all uses of fsync within the PostgreSQL server, so if you turn it off PostgreSQL should never issue fsync. The only exceptions are some utility tools (eg. pg_basebackup) which do not read the configuration file. -- Andreas Karlsson -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance