Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1YM2uX-0006kv-3A for pgsql-performance@arkaria.postgresql.org; Thu, 12 Feb 2015 23:11:05 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.80) (envelope-from ) id 1YM2uW-0006AH-0O for pgsql-performance@arkaria.postgresql.org; Thu, 12 Feb 2015 23:11:04 +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 1YM2uU-0006AA-SB for pgsql-performance@postgresql.org; Thu, 12 Feb 2015 23:11:02 +0000 Received: from mail.catalyst.net.nz ([2404:130:0:10::40:0]) by magus.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1YM2uL-0004RX-3I for pgsql-performance@postgresql.org; Thu, 12 Feb 2015 23:11:01 +0000 Received: from localhost (localhost [127.0.0.1]) by mail.catalyst.net.nz (Postfix) with ESMTP id 28F2A326D4; Fri, 13 Feb 2015 12:10:47 +1300 (NZDT) X-Virus-Scanned: Debian amavisd-new at catalyst.net.nz Received: from mail.catalyst.net.nz ([127.0.0.1]) by localhost (bertrand.catalyst.net.nz [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id OTw9Nid5iTkS; Fri, 13 Feb 2015 12:10:46 +1300 (NZDT) Received: from [IPv6:2404:130:0:1000:75b8:d66b:8a44:ca83] (unknown [IPv6:2404:130:0:1000:75b8:d66b:8a44:ca83]) (Authenticated sender: mark.kirkwood) by mail.catalyst.net.nz (Postfix) with ESMTPSA id 4DB5431D28; Fri, 13 Feb 2015 12:10:46 +1300 (NZDT) Message-ID: <54DD32F6.6010100@catalyst.net.nz> Date: Fri, 13 Feb 2015 12:10:46 +1300 From: Mark Kirkwood User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 MIME-Version: 1.0 To: "Gudmundsson Martin (mg)" , =?UTF-8?B?THVpcyBBbnRvbmlvIERpYXMgZGUgU8OhIEp1bmlvcg==?= CC: "pgsql-performance@postgresql.org" Subject: Re: Survey: Max TPS you've ever seen References: <54D9269C.9080808@archidevsys.co.nz> <54DAA2D3.1000605@catalyst.net.nz> <2E5766F28426E547AF0A2A870FAE630D32BAD8@SEGOTNC5182-N2.vcn.ds.volvo.net> In-Reply-To: <2E5766F28426E547AF0A2A870FAE630D32BAD8@SEGOTNC5182-N2.vcn.ds.volvo.net> Content-Type: text/plain; charset=utf-8; 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 13/02/15 00:20, Gudmundsson Martin (mg) wrote: > Hi all! > >> - checkpoint_segments 1000 >> - checkpoint_completion_target 0.9 >> - wal_buffers 256MB >> - shared_buffers 31 gb >> - max_connections 500 > > I see that some of you are using wal_buffers = 256MB. > I was under the impression that Postgres will not benefit from higher value than the segment size, i.e. 16MB. More than that will not do/help anything. > > What's the reasoning behind setting it to higher than 16MB? Do I have old information? > > Best regards, Martin > There was some discussion a while ago in which 32MB and 8MB both demonstrated better performance than 16MB (probably related to the fact the the default wal file size is 16MB). We just experimented further with bigger values, and saw some improvement. Cheers Mark -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance