Received: from localhost (unknown [200.46.204.183]) by mail.postgresql.org (Postfix) with ESMTP id D54D96502F0 for ; Fri, 12 Dec 2008 14:19:04 -0400 (AST) Received: from mail.postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 24379-06 for ; Fri, 12 Dec 2008 14:19:00 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from outmail128052.authsmtp.co.uk (outmail128052.authsmtp.co.uk [62.13.128.52]) by mail.postgresql.org (Postfix) with ESMTP id 7D15F64FE7B for ; Fri, 12 Dec 2008 14:19:00 -0400 (AST) Received: from mail-c188.authsmtp.com (mail-c188.authsmtp.com [62.13.128.25]) by punt8.authsmtp.com (8.14.2/8.14.2/Kp) with ESMTP id mBCIIKKm051835; Fri, 12 Dec 2008 18:18:20 GMT Received: from [192.168.0.3] (85-211-226-82.dyn.gotadsl.co.uk [85.211.226.82]) (authenticated bits=0) by mail.authsmtp.com (8.14.2/8.14.2/Kp) with ESMTP id mBCIII49087155; Fri, 12 Dec 2008 18:18:19 GMT Subject: Re: benchmarking the query planner From: Simon Riggs To: Greg Stark Cc: Robert Haas , Tom Lane , Kevin Grittner , "jd@commandprompt.com" , Josh Berkus , Greg Smith , pgsql-hackers@postgresql.org In-Reply-To: <4136ffa0812121001x3fde1871t558fd8c58070b7d@mail.gmail.com> References: <603c8f070812061019r5aca3aajeaa5493b11c5feff@mail.gmail.com> <1229039044.13078.193.camel@hp_dx2400_1> <4136ffa0812111823u645b6ec9wdca60b3da4b00499@mail.gmail.com> <1229072675.13078.196.camel@hp_dx2400_1> <603c8f070812120344m67ef2c1fs41806cfb4ff9e396@mail.gmail.com> <1229093975.13078.275.camel@ebony.2ndQuadrant> <87tz99s7bu.fsf@oxford.xeocode.com> <1229100057.8673.29.camel@ebony.2ndQuadrant> <87hc59s4qx.fsf@oxford.xeocode.com> <1229103209.8673.62.camel@ebony.2ndQuadrant> <4136ffa0812121001x3fde1871t558fd8c58070b7d@mail.gmail.com> Content-Type: text/plain Date: Fri, 12 Dec 2008 18:18:02 +0000 Message-Id: <1229105882.8673.74.camel@ebony.2ndQuadrant> Mime-Version: 1.0 X-Mailer: Evolution 2.12.0 Content-Transfer-Encoding: 7bit X-Server-Quench: 40e7be51-c879-11dd-aecc-001871e930f4 X-AuthRoute: OCdxZQATClZOTQEd DAteCiNZVAwpPBRK HVkIKg5MJUcNSQVJ NksafhtFaQdbaVxS HGQLW1xEUVV7WGt/ agMfZQBDYEtPQQdo VlZBQE1QEQdtHhxP W2xtK2ALcwxGcHlx YEMsX3hbWgp+dRN6 EBtRFHBVbWBpdWEe BBRFJlYHIx5Kfh5N bVEqXXANN2FJBC9q VzwTFhsSEA9kHWxf TwcGLVcbW0UKGDF0 WxAPVSwyEFcUDz03 JhogJ0R0 X-Authentic-SMTP: 61633235383639.cat.dmpriest.net.uk:1378/Kp X-Report-SPAM: If SPAM / abuse - report it at: http://www.authsmtp.com/abuse X-Virus-Status: No virus detected - but ensure you scan with your own anti-virus system! X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0 tagged_above=0 required=5 tests=none X-Spam-Level: X-Archive-Number: 200812/978 X-Sequence-Number: 129607 On Fri, 2008-12-12 at 18:01 +0000, Greg Stark wrote: > I think you need to find two different formulas, one which represents > a clustered table and one which represents randomly distributed data. > Then you need a way to measure just how clustered the data is so you > know how much weight to give each formula. Perhaps comparing the > number of duplicates in whole-block samples versus overall random > selections would give that measure. Please read the Chaudhuri paper. -- Simon Riggs www.2ndQuadrant.com PostgreSQL Training, Services and Support