Received: from localhost (maia-4.hub.org [200.46.204.183]) by postgresql.org (Postfix) with ESMTP id 71C919FB911 for ; Thu, 22 Mar 2007 10:26:59 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.183]) (amavisd-new, port 10024) with ESMTP id 88675-01 for ; Thu, 22 Mar 2007 10:26:55 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.4 Received: from relay.icomedias.com (relay.icomedias.com [62.99.232.66]) by postgresql.org (Postfix) with ESMTP id D3B5F9FB7F1 for ; Thu, 22 Mar 2007 10:26:54 -0300 (ADT) Received: from loki.icomedias.com ([10.192.17.128]) by relay.icomedias.com (8.13.7/8.13.7) with ESMTP id l2MDQqGm028564; Thu, 22 Mar 2007 14:26:52 +0100 From: Mario Weilguni To: pgsql-performance@postgresql.org Subject: Re: Performance of count(*) Date: Thu, 22 Mar 2007 14:26:51 +0100 User-Agent: KMail/1.9.5 Cc: ismo.tuononen@solenovo.fi, Albert Cervera Areny References: <200703221208.19358.albert@sedifa.com> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Message-Id: <200703221426.51948.mweilguni@sime.com> X-Scanned-By: MIMEDefang 2.57 on 10.192.64.104 X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200703/315 X-Sequence-Number: 23720 Am Donnerstag, 22. M=C3=A4rz 2007 12:30 schrieb ismo.tuononen@solenovo.fi: > approximated count????? > > why? who would need it? where you can use it? > > calculating costs and desiding how to execute query needs > approximated count, but it's totally worthless information for any user > IMO. No, it is not useless. Try:=20 http://www.google.com/search?hl=3Dde&q=3Dtest&btnG=3DGoogle-Suche&meta=3D Do you really think google counted each of those individual 895 million=20 results? It doesn't. In fact, the estimate of google can be off by an order= =20 of magnitude, and still nobody complains...