Received: from localhost (unknown [200.46.208.211]) by mail.postgresql.org (Postfix) with ESMTP id C1CBF6324E8 for ; Tue, 2 Jun 2009 11:57:08 -0300 (ADT) Received: from mail.postgresql.org ([200.46.204.86]) by localhost (mx1.hub.org [200.46.208.211]) (amavisd-maia, port 10024) with ESMTP id 97519-03 for ; Tue, 2 Jun 2009 11:56:57 -0300 (ADT) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from wf-out-1314.google.com (wf-out-1314.google.com [209.85.200.173]) by mail.postgresql.org (Postfix) with ESMTP id E676C634841 for ; Tue, 2 Jun 2009 11:57:06 -0300 (ADT) Received: by wf-out-1314.google.com with SMTP id 28so2586975wfc.28 for ; Tue, 02 Jun 2009 07:57:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:references:message-id:from:to :in-reply-to:content-type:content-transfer-encoding:x-mailer :mime-version:subject:date:cc; bh=B1PdYqHPleGIMgsABP69NwY0Mw/bL50lS041Lwguv0M=; b=sK93gXZ3V89hXUZUcjAN9iiUB1cJWR+eqKbQtL6/T7ytvZJjYg+sMxNCpcKrmVZHff y8H0LqjR5Dx05OwT3cV1SFYMhjCfzs6E6OUk9IPt7pbkMAnK+etex+DdTC0cpUxQlUGM 0S+voBFvq+OFqfVSlLlvI7e/BL5zetlcpPRC4= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=references:message-id:from:to:in-reply-to:content-type :content-transfer-encoding:x-mailer:mime-version:subject:date:cc; b=Oa9viIlyxusIDb0ez4Uq5qor65vLDNFt83OeiAgI+iUElGEKZ3QGV+BccgF0SdabYx GeGiKSu2XMKpf2rao+KewBDkgYeNil337jH4yZB+tcgqqchsx0Z16bPmxUVrHoaUEG57 bRKAeq8KrXlyWvDGq/L9dkWOkxr7kmbEoWnIM= Received: by 10.143.162.8 with SMTP id p8mr2589303wfo.34.1243954624984; Tue, 02 Jun 2009 07:57:04 -0700 (PDT) Received: from ?192.168.30.127? (static-216-83-108-4.sniparpa.net [216.83.108.4]) by mx.google.com with ESMTPS id 22sm1437791wfg.7.2009.06.02.07.57.03 (version=TLSv1/SSLv3 cipher=RC4-MD5); Tue, 02 Jun 2009 07:57:04 -0700 (PDT) References: <603c8f070905281830g2e5419c4xad2946d149e21f9d@mail.gmail.com> <4A1F4FD5.7060204@timbira.com> <4A249CE9.6050708@cheapcomplexdevices.com> <1243950060.23910.58.camel@ebony.2ndQuadrant> <11926.1243953507@sss.pgh.pa.us> Message-Id: From: Robert Haas To: Tom Lane In-Reply-To: <11926.1243953507@sss.pgh.pa.us> Content-Type: text/plain; charset=us-ascii; format=flowed; delsp=yes Content-Transfer-Encoding: 7bit X-Mailer: iPhone Mail (5H11) Mime-Version: 1.0 (iPhone Mail 5H11) Subject: Re: explain analyze rows=%.0f Date: Tue, 2 Jun 2009 10:56:59 -0400 Cc: Simon Riggs , Ron Mayer , Euler Taveira de Oliveira , "pgsql-hackers@postgresql.org" 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: 200906/152 X-Sequence-Number: 139207 ...Robert On Jun 2, 2009, at 10:38 AM, Tom Lane wrote: > Robert Haas writes: >> On Jun 2, 2009, at 9:41 AM, Simon Riggs >> wrote: >>> You're right that the number of significant digits already exceeds >>> the >>> true accuracy of the computation. I think what Robert wants to see >>> is >>> the exact value used in the calc, so the estimates can be checked >>> more >>> thoroughly than is currently possible. > >> Bingo. > > Uh, the planner's estimate *is* an integer. What was under discussion > (I thought) was showing some fractional digits in the case where > EXPLAIN > ANALYZE is outputting a measured row count that is an average over > multiple loops, and therefore isn't necessarily an integer. In that > case the measured value can be considered arbitrarily precise --- > though > I think in practice one or two fractional digits would be plenty. We're in violent agreement here. ...Robert