Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1Ya7aD-0001MA-Ik for pgsql-hackers@arkaria.postgresql.org; Mon, 23 Mar 2015 19:00:17 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.80) (envelope-from ) id 1Ya7aD-00055c-1Y for pgsql-hackers@arkaria.postgresql.org; Mon, 23 Mar 2015 19:00:17 +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 1Ya7aB-000556-MN for pgsql-hackers@postgresql.org; Mon, 23 Mar 2015 19:00:15 +0000 Received: from boipeva.ensmp.fr ([194.214.158.101]) by makus.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1Ya7a7-00080q-SK for pgsql-hackers@postgresql.org; Mon, 23 Mar 2015 19:00:13 +0000 Received: from cri.ensmp.fr (154.237.219.88.rev.sfr.net [88.219.237.154]) (authenticated bits=0) by boipeva.ensmp.fr (8.14.9/8.14.9/JMMC-22/Oct/2013) with ESMTP id t2NJ05aj006688 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NO); Mon, 23 Mar 2015 20:00:05 +0100 Date: Mon, 23 Mar 2015 20:00:04 +0100 (CET) From: Fabien COELHO X-X-Sender: fabien@sto To: Andres Freund cc: PostgreSQL Developers Subject: Re: PATCH: pgbench - merging transaction logs In-Reply-To: <20150323162927.GC15229@alap3.anarazel.de> Message-ID: References: <550CCBE5.8060009@2ndquadrant.com> <20150323162927.GC15229@alap3.anarazel.de> User-Agent: Alpine 2.10 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Miltered: at boipeva.ensmp.fr with ID 551062B5.000 by Joe's j-chkmail (http : // j-chkmail dot ensmp dot fr)! X-j-chkmail-Auth: USER-ID fabien.coelho X-j-chkmail-Enveloppe: 551062B5.000 from 154.237.219.88.rev.sfr.net/154.237.219.88.rev.sfr.net/88.219.237.154/cri.ensmp.fr/ X-Pg-Spam-Score: -1.9 (-) List-Archive: List-Help: List-ID: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: X-Mailing-List: pgsql-hackers Precedence: bulk Sender: pgsql-hackers-owner@postgresql.org > Guys, I don't see this theoretical discussion going anywhere. I think > it's time to simply implement this and evaluate it on a bigger > machine. Sure. I was kind of hoping that someone else would implement it, because I'm a reviewer on this one, and I do not have the bigger machine at hand either:-) If nothing happens and when I have some time, I'll do it. > It can't take very long to implement tosimply just write to one > file instead of the multiple files as now. Sure. > The posix guaranteed fprintf locking should already take care of the > rest. I think I would try with snprintf to reduce locking. Note that I'm first trying to evaluate logging overhead, but I'm quite far from Tomas figures at the moment, looks more like 20% overhead (12 threads read-only load, runs at about 130000 tps with full logging, 160000 without, repeated 5 times with the similar results). In such a case, a mutex would be a bad idea, but I must add that detailed logging is a plain bad idea as well! -- Fabien. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers