Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1VnqPs-0003oV-I3 for pgsql-performance@arkaria.postgresql.org; Tue, 03 Dec 2013 13:53:32 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.80) (envelope-from ) id 1VnqPs-000211-1Q for pgsql-performance@arkaria.postgresql.org; Tue, 03 Dec 2013 13:53:32 +0000 Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29]) by malur.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1VnqPr-00020v-96 for pgsql-performance@postgresql.org; Tue, 03 Dec 2013 13:53:31 +0000 Received: from smtprelay0254.b.hostedemail.com ([64.98.42.254] helo=smtprelay.b.hostedemail.com) by magus.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1VnqPn-0004M2-SA for pgsql-performance@postgresql.org; Tue, 03 Dec 2013 13:53:30 +0000 Received: from filter.hostedemail.com (b-bigip1 [10.5.19.254]) by smtprelay04.b.hostedemail.com (Postfix) with ESMTP id DC7EC7B864; Tue, 3 Dec 2013 13:53:25 +0000 (UTC) X-Session-Marker: 616C76686572726540616C76682E6E6F2D69702E6F7267 X-Spam-Summary: 66, 4.2, 0, , d41d8cd98f00b204, alvherre@alvh.no-ip.org, :::, RULES_HIT:41:355:379:599:967:973:988:989:1260:1277:1311:1312:1313:1314:1345:1359:1437:1515:1516:1518:1519:1534:1539:1593:1594:1595:1596:1711:1714:1730:1747:1777:1792:2393:2525:2561:2564:2682:2685:2828:2859:2933:2937:2939:2942:2945:2947:2951:2954:3022:3138:3139:3140:3141:3142:3350:3865:3866:3867:3873:3874:3934:3936:3938:3941:3944:3947:3950:3953:3956:3959:4250:4321:4605:4659:5007:6261:8599:8603:9025:9121:9388:10004:10400:10848:11232:11256:11257:11658:11914:12043:12292:12296:12517:12519:12555:12682:12698:12737:12933:12937:12938:13069:13095:13103:13311:13357:13845:13894:13895, 0, RBL:none, CacheIP:none, Bayesian:0.5, 0.5, 0.5, Netcheck:none, DomainCache:0, MSF:not bulk, SPF:fn, MSBL:0, DNSBL:none, Custom_rules:0:0:0 X-HE-Tag: fan84_752d934a99616 X-Filterd-Recvd-Size: 1612 Received: from eldon.alvh.no-ip.org (pc-223-216-160-190.cm.vtr.net [190.160.216.223]) (Authenticated sender: alvherre@alvh.no-ip.org) by omf10.b.hostedemail.com (Postfix) with ESMTPA; Tue, 3 Dec 2013 13:53:25 +0000 (UTC) Received: by eldon.alvh.no-ip.org (Postfix, from userid 1000) id 571B21FC8; Tue, 3 Dec 2013 10:53:23 -0300 (CLST) Date: Tue, 3 Dec 2013 10:53:23 -0300 From: Alvaro Herrera To: Metin Doslu Cc: pgsql-performance@postgresql.org Subject: Re: Parallel Select query performance and shared buffers Message-ID: <20131203135323.GA5158@eldon.alvh.no-ip.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Pg-Spam-Score: -1.9 (-) 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 Metin Doslu wrote: > When we send concurrent Select queries to these tables, query performance > doesn't scale out with the number of CPU cores. We find that complex Select > queries scale out better than simpler ones. We also find that increasing > the block size from 8 KB to 32 KB, or increasing shared_buffers to include > the working set mitigates the problem to some extent. Maybe you could help test this patch: http://www.postgresql.org/message-id/20131115194725.GG5489@awork2.anarazel.de -- Álvaro Herrera 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