Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1XbmnR-00018O-HT for pgsql-performance@arkaria.postgresql.org; Wed, 08 Oct 2014 08:40:33 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.80) (envelope-from ) id 1XbmnR-0006tx-0C for pgsql-performance@arkaria.postgresql.org; Wed, 08 Oct 2014 08:40:33 +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 1XbmnP-0006rk-TX for pgsql-performance@postgresql.org; Wed, 08 Oct 2014 08:40:32 +0000 Received: from forward18.mail.yandex.net ([95.108.253.143]) by makus.postgresql.org with esmtps (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1XbmnM-0007F9-6F for pgsql-performance@postgresql.org; Wed, 08 Oct 2014 08:40:30 +0000 Received: from web3g.yandex.ru (web3g.yandex.ru [95.108.252.103]) by forward18.mail.yandex.net (Yandex) with ESMTP id F2FBD1782176 for ; Wed, 8 Oct 2014 12:40:23 +0400 (MSK) Received: from 127.0.0.1 (localhost [127.0.0.1]) by web3g.yandex.ru (Yandex) with ESMTP id 91C673961025; Wed, 8 Oct 2014 12:40:23 +0400 (MSK) Received: from rtr.tgt72.ru (rtr.tgt72.ru [77.242.110.178]) by web3g.yandex.ru with HTTP; Wed, 08 Oct 2014 12:40:23 +0400 From: Vladimir Kamarzin To: "pgsql-performance@postgresql.org" In-Reply-To: <22483.1412690194@sss.pgh.pa.us> References: <29191412676815@web25o.yandex.ru> <22483.1412690194@sss.pgh.pa.us> Subject: Re: Performance degradation in 324577f39bc8738ed0ec24c36c5cb2c2f81ec660 MIME-Version: 1.0 Message-Id: <2012271412757623@web3g.yandex.ru> X-Mailer: Yamail [ http://yandex.ru ] 5.0 Date: Wed, 08 Oct 2014 14:40:23 +0600 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=koi8-r X-Pg-Spam-Score: -0.9 (/) 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 07.10.2014, 19:59, "Tom Lane" : > Vladimir Kamarzin writes: >> šAfter upgrade from 9.3.1 to 9.3.5 we expirienced a slight performance degradation of all queries. Query time increased to some amount of ms, mostly in range of 100ms. Some actions in our application results in a lot of small queries and in such cases performance degradation is very significant - total action performs for a 2-3 times longer then before (15s -> 40s, etc). >> šUsing git-bisect we've found a bad revision causes performance drop: it is 324577f39bc8738ed0ec24c36c5cb2c2f81ec660 > > Hm. šIf you're going to do queries that involve update/delete across large > inheritance trees, that bug fix is unavoidably going to cost you some > cycles. Yeah, we're actually noticed significantly increased CPU load while running on 9.3.5. > I am wondering if you've > misidentified the commit that made the difference --- especially since you > claim there's a penalty for "all" queries, which there manifestly couldn't > be with this particular patch. No, problem appears exactly on this commit. Actually I don't really sure about "all": we don't see degradation when performing plain SELECTs manually, but comparing logged query time of some SELECTs we see the differences. Here is example 42ms -> 250ms: http://pastebin.ca/2855292 http://pastebin.ca/2855290 > šIf not, there must be something rather > unusual about your queries or schema. šCare to provide a self-contained > test case? I'm afraid we cannot do this now. If you wish, we can give you ssh access to the test server to investigate the problem. -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance