Received: from maia.hub.org (maia-2.hub.org [200.46.204.251]) by mail.postgresql.org (Postfix) with ESMTP id 671501337B99 for ; Thu, 10 Feb 2011 13:30:55 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by maia.hub.org (mx1.hub.org [200.46.204.251]) (amavisd-maia, port 10024) with ESMTP id 93272-08 for ; Thu, 10 Feb 2011 17:30:48 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from smtp.peak6.com (smtp.peak6.com [38.98.137.6]) by mail.postgresql.org (Postfix) with ESMTP id 108321337B7E for ; Thu, 10 Feb 2011 13:30:47 -0400 (AST) X-AuditID: 0a64cb1e-b7c55ae000000bfb-70-4d5420c712c5 Message-ID: <4D5420C6.3030608@peak6.com> Date: Thu, 10 Feb 2011 11:30:46 -0600 From: Shaun Thomas Reply-To: sthomas@peak6.com Organization: Peak6 User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.7) Gecko/20100720 Lightning/1.0b2 Thunderbird/3.1.1 MIME-Version: 1.0 To: Kevin Grittner CC: Josh Berkus , Robert Haas , "pgsql-performance@postgresql.org" Subject: Re: Why we don't want hints Was: Slow count(*) again... References: <201102012247.p11Ml6u02682@momjian.us> <4D48914B.4050403@dunslane.net> <4D489AD1.1010105@vmsinfo.com> <4D499E55.4020107@vmsinfo.com> <4D49A6B9.4060608@2ndquadrant.com> <4D49C482.4010707@vmsinfo.com> <4D49F0BA.9000901@2ndquadrant.com> <4D4A16BF.1020304@vmsinfo.com> <4D4A4844.3020409@2ndquadrant.com> <4D4AD9F6.6040903@vmsinfo.com> <4D4AE16E.9040807@peak6.com> <4D4B17B4.9030406@vmsinfo.com> <4D4B1F5B.4060403@peak6.com> <4D4B261B.6010303@vmsinfo.com> <4D4B2E8A.7010402@vmsinfo.com> <4D4B3395.6010007@agliodbs.com> <4D4B394E.9080505@vmsinfo.com> <4D4B5A73.3080302@agliodbs.com> <4D53C1C0020000250003A783@gw.wicourts.gov> <4D541B22.9080000@peak6.com> <4D53CA4F020000250003A789@gw.wicourts.gov> In-Reply-To: <4D53CA4F020000250003A789@gw.wicourts.gov> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed content-transfer-encoding: 7bit X-Brightmail-Tracker: AAAAAQAAAZE= X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=-1.91 tagged_above=-10 required=5 tests=BAYES_00=-1.9, T_RP_MATCHES_RCVD=-0.01 X-Spam-Level: X-Archive-Number: 201102/336 X-Sequence-Number: 42474 On 02/10/2011 11:21 AM, Kevin Grittner wrote: > Something like this syntax?: > > JOIN WITH (correlation_factor=0.3) I was thinking more: JOIN foo_tab USING (foo_id) WITH (COST=50) or something, to exploit the hooks that already exist for functions, for example. But it's still an interesting concept. Tell the optimizer what you want and how the data is really related in cases where it's wrong, and let it figure out the best path. -- Shaun Thomas OptionsHouse | 141 W. Jackson Blvd. | Suite 800 | Chicago IL, 60604 312-676-8870 sthomas@peak6.com ______________________________________________ See http://www.peak6.com/email_disclaimer.php for terms and conditions related to this email