Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1YXCco-00028m-OM for pgsql-performance@arkaria.postgresql.org; Sun, 15 Mar 2015 17:46:54 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.80) (envelope-from ) id 1YXCco-0008K7-7y for pgsql-performance@arkaria.postgresql.org; Sun, 15 Mar 2015 17:46:54 +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 1YXCcn-0008Jz-D9 for pgsql-performance@postgresql.org; Sun, 15 Mar 2015 17:46:53 +0000 Received: from mail.anarazel.de ([217.115.131.40]) by makus.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1YXCck-0002S4-4F for pgsql-performance@postgresql.org; Sun, 15 Mar 2015 17:46:51 +0000 Received: from intern.anarazel.de (p5DDC543A.dip0.t-ipconnect.de [93.220.84.58]) (Authenticated sender: andres@anarazel.de) by mail.anarazel.de (Postfix) with ESMTPSA id C19A0860001; Sun, 15 Mar 2015 18:46:47 +0100 (CET) Date: Sun, 15 Mar 2015 18:46:47 +0100 From: Andres Freund To: ik@postgresql-consulting.com Cc: Scott Marlowe , Robert Kaye , Josh Krupka , PostgreSQL Performance Subject: Re: MusicBrainz postgres performance issues Message-ID: <20150315174646.GH9324@alap3.anarazel.de> References: <9E71CCBE-4CDF-482E-878D-6C16027B6283@musicbrainz.org> <20150315135022.GC19792@alap3.anarazel.de> <20150315172048.GG9324@alap3.anarazel.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Pg-Spam-Score: -4.2 (----) 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 2015-03-15 20:42:51 +0300, Ilya Kosmodemiansky wrote: > On Sun, Mar 15, 2015 at 8:20 PM, Andres Freund wrote: > > On 2015-03-15 11:09:34 -0600, Scott Marlowe wrote: > >> shared_mem of 12G is almost always too large. I'd drop it down to ~1G or so. > > > > I think that's a outdated wisdom, i.e. not generally true. > > Quite agreed. With note, that proper configured controller with BBU is needed. That imo doesn't really have anything to do with it. The primary benefit of a BBU with writeback caching is accelerating (near-)synchronous writes. Like the WAL. But, besides influencing the default for wal_buffers, a larger shared_buffers doesn't change the amount of synchronous writes. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance