Received: from localhost (unknown [200.46.204.183]) by developer.postgresql.org (Postfix) with ESMTP id 0457B2E0050 for ; Mon, 9 Jun 2008 18:24:04 -0300 (ADT) Received: from developer.postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-maia, port 10024) with ESMTP id 91741-04 for ; Mon, 9 Jun 2008 18:23:54 -0300 (ADT) X-Greylist: delayed 00:06:45.57796 by SQLgrey-1.7.6 Received: from yw-out-2324.google.com (yw-out-2324.google.com [74.125.46.29]) by developer.postgresql.org (Postfix) with ESMTP id C22C72E0047 for ; Mon, 9 Jun 2008 18:23:57 -0300 (ADT) Received: by yw-out-2324.google.com with SMTP id 3so1308349ywj.73 for ; Mon, 09 Jun 2008 14:23:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to :subject:cc:in-reply-to:mime-version:content-type:references; bh=pJwMZdZJ6Tx8dPoZmI+HWAIORIhzWxnaD9aRabcgvlU=; b=AE2fNmhdpi9/84IzecNRI+IiyT5oZq9+lDkNyCWF897R2lRrw7AKouF9qLqVqrJDVU wUhfJ/DZqhQ8ClYle02YW0jtdUcmixj5vzxxxDEMRUY5KP/7m9SGezqBjey/j/HkG37j EKMs9Dnq2aieNFXSNE2P8dYgl/6ocam5b4/7o= DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version :content-type:references; b=NoS19s8HsBzN5L7391rhwr4m66Q3HpRo7sg+7greUXA1fu/kLsoHnZ5NKMdwMjYej8 7C5U/mHyNDONyT3Dvz1gEIo+suma4zz1MbShhR3cpESHBgzmZXCmYkYuLb0ocJBVK69n jKCjJFKetku3tMvZaWp1ctWdw6jUnZQ+QXHkQ= Received: by 10.151.112.12 with SMTP id p12mr6994691ybm.195.1213046228796; Mon, 09 Jun 2008 14:17:08 -0700 (PDT) Received: by 10.150.199.4 with HTTP; Mon, 9 Jun 2008 14:17:08 -0700 (PDT) Message-ID: <48ca23600806091417u546f3b6dm6314bc55aaa147f6@mail.gmail.com> Date: Mon, 9 Jun 2008 23:17:08 +0200 From: "Hakan Kocaman" To: "Gregory Stark" Subject: Re: Overhauling GUCS Cc: "Josh Berkus" , "Joshua D. Drake" , "Tom Lane" , "Robert Treat" , pgsql-hackers@postgresql.org, "Peter Eisentraut" , "Greg Smith" , "Andreas Pflug" , Decibel! In-Reply-To: <87d4mqwdm8.fsf@oxford.xeocode.com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_16545_15913876.1213046228761" References: <48409D1E.3070208@agliodbs.com> <29525.1212613052@sss.pgh.pa.us> <200806061435.01196.peter_e@gmx.net> <200806061624.29105.xzilla@users.sourceforge.net> <8358.1212797962@sss.pgh.pa.us> <1212800891.14299.35.camel@jd-laptop> <87hcc3le52.fsf@oxford.xeocode.com> <484D6C1C.5070004@agliodbs.com> <87d4mqwdm8.fsf@oxford.xeocode.com> X-Virus-Scanned: Maia Mailguard 1.0.1 X-Spam-Status: No, hits=0.001 tagged_above=0 required=5 tests=HTML_MESSAGE=0.001 X-Spam-Level: X-Archive-Number: 200806/423 X-Sequence-Number: 119536 ------=_Part_16545_15913876.1213046228761 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline On 6/9/08, Gregory Stark wrote: > > "Josh Berkus" writes: > > > Where analyze does systematically fall down is with databases over 500GB > in > > size, but that's not a function of d_s_t but rather of our tiny sample > size. > > > n_distinct. For that Josh is right, we *would* need a sample size > proportional > to the whole data set which would practically require us to scan the whole > table (and have a technique for summarizing the results in a nearly > constant > sized data structure). > > Hi, is this (summarizing results in a constant sized data structure) something which could be achived by Bloom-Filters ? http://archives.postgresql.org/pgsql-general/2008-06/msg00076.php Kind regards Hakan Kocaman ------=_Part_16545_15913876.1213046228761 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline

On 6/9/08, Gregory Stark <stark@enterprisedb.com> wrote:
"Josh Berkus" <josh@agliodbs.com> writes:

> Where analyze does systematically fall down is with databases over 500GB in
> size, but that's not a function of d_s_t but rather of our tiny sample size.


n_distinct. For that Josh is right, we *would* need a sample size proportional
to the whole data set which would practically require us to scan the whole
table (and have a technique for summarizing the results in a nearly constant
sized data structure).


Hi,
is this (summarizing results in a constant sized data structure) something which could be achived by Bloom-Filters ?
http://archives.postgresql.org/pgsql-general/2008-06/msg00076.php

Kind regards
Hakan Kocaman

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