Received: from makus.postgresql.org (makus.postgresql.org [98.129.198.125]) by mail.postgresql.org (Postfix) with ESMTP id 6B64DBEAE5C for ; Wed, 25 Jul 2012 11:56:37 -0300 (ADT) Received: from sss.pgh.pa.us ([66.207.139.130]) by makus.postgresql.org with esmtp (Exim 4.72) (envelope-from ) id 1Su30u-0007qP-2y for pgsql-performance@postgresql.org; Wed, 25 Jul 2012 14:56:37 +0000 Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.14.5/8.14.5) with ESMTP id q6PEuKsQ022920; Wed, 25 Jul 2012 10:56:20 -0400 (EDT) From: Tom Lane To: Aleksei Arefjev cc: Richard Huxton , pgsql-performance@postgresql.org Subject: Re: transactions start time In-reply-to: References: <500ED9A2.3040101@archonet.com> Comments: In-reply-to Aleksei Arefjev message dated "Wed, 25 Jul 2012 09:52:35 +0300" Date: Wed, 25 Jul 2012 10:56:20 -0400 Message-ID: <22919.1343228180@sss.pgh.pa.us> X-Pg-Spam-Score: -1.9 (-) X-Archive-Number: 201207/326 X-Sequence-Number: 47507 Aleksei Arefjev writes: > On 24 July 2012 20:21, Richard Huxton wrote: >> I'm not sure if I'm reading this right, but are there more than 48 million >> BEGINs that took 0s each (presumably rounded down) and then a handful >> taking about 0.8s? I'm wondering exactly where/how the duration was measured. If it was at a client, maybe the apparent delay had something to do with network glitches? It seems suspicious that all the outliers are around 0.8s. It would be useful to look to see if there's any comparable pattern for statements other than BEGIN. As Richard says, a BEGIN by itself ought to take negligible time. regards, tom lane