Received: from magus.postgresql.org (magus.postgresql.org [87.238.57.229]) by mail.postgresql.org (Postfix) with ESMTP id 4BC1F4DA6AA for ; Thu, 10 May 2012 09:09:40 -0300 (ADT) Received: from plane.gmane.org ([80.91.229.3]) by magus.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1SSSBe-0001rL-Hd for pgsql-performance@postgresql.org; Thu, 10 May 2012 12:09:39 +0000 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1SSSBN-0004Uh-1Z for pgsql-performance@postgresql.org; Thu, 10 May 2012 14:09:21 +0200 Received: from 217.110.94.67 ([217.110.94.67]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 10 May 2012 14:09:21 +0200 Received: from spam_eater by 217.110.94.67 with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 10 May 2012 14:09:21 +0200 X-Injected-Via-Gmane: http://gmane.org/ To: pgsql-performance@postgresql.org From: Thomas Kellerer Subject: Re: Could synchronous streaming replication really degrade the performance of the primary? Date: Thu, 10 May 2012 14:10:48 +0200 Lines: 10 Message-ID: References: <61B94EF1D7774715BC565DD84C731BDD@maumau> <37AC2C75CBA4411F84F5F995EDF91503@maumau> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Complaints-To: usenet@dough.gmane.org X-Gmane-NNTP-Posting-Host: 217.110.94.67 User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.23) Gecko/20090812 Thunderbird/2.0.0.23 Mnenhy/0.7.6.666 In-Reply-To: <37AC2C75CBA4411F84F5F995EDF91503@maumau> X-Pg-Spam-Score: -0.7 (/) X-Archive-Number: 201205/76 X-Sequence-Number: 46900 MauMau, 10.05.2012 13:34: > Today, they told me that they ran the test on two virtual machines on > a single physical machine. Which means that both databases shared the same I/O system (harddisks). Thererfor it's not really surprising that the overall performance goes down if you increase the I/O load. A more realistic test (at least in my opinion) would have been to have two separate computers with two separate I/O systems