X-Original-To: pgsql-performance-postgresql.org@localhost.postgresql.org Received: from localhost (av.hub.org [200.46.204.144]) by postgresql.org (Postfix) with ESMTP id 333FF9DCD01 for ; Thu, 23 Feb 2006 14:55:04 -0400 (AST) Received: from postgresql.org ([200.46.204.71]) by localhost (av.hub.org [200.46.204.144]) (amavisd-new, port 10024) with ESMTP id 50572-03 for ; Thu, 23 Feb 2006 14:55:03 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- Received: from gwmta.wicourts.gov (gwmta.wicourts.gov [165.219.244.99]) by postgresql.org (Postfix) with ESMTP id 986AD9DCD00 for ; Thu, 23 Feb 2006 14:55:00 -0400 (AST) Received: from Courts-MTA by gwmta.wicourts.gov with Novell_GroupWise; Thu, 23 Feb 2006 12:54:59 -0600 Message-Id: <43FDB09C.EE98.0025.0@wicourts.gov> X-Mailer: Novell GroupWise Internet Agent 7.0 Date: Thu, 23 Feb 2006 12:54:52 -0600 From: "Kevin Grittner" To: "Greg Stark" Cc: Subject: Re: Good News re count(*) in 8.1 References: <43FC4384.EE98.0025.0@wicourts.gov> <87irr6zq7j.fsf@stark.xeocode.com> In-Reply-To: <87irr6zq7j.fsf@stark.xeocode.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="=__Part3D1F8DEC.1__=" X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0.057 required=5 tests=[AWL=0.057] X-Spam-Score: 0.057 X-Spam-Level: X-Archive-Number: 200602/373 X-Sequence-Number: 17359 --=__Part3D1F8DEC.1__= Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Content-Disposition: inline >>> On Wed, Feb 22, 2006 at 9:52 pm, in message <87irr6zq7j.fsf@stark.xeocode.com>, Greg Stark wrote: > "Kevin Grittner" writes: > >> There have been several times that I have run a SELECT COUNT(*) on an entire >> table on all central machines. On identical hardware, with identical data, >> and equivalent query loads, the PostgreSQL databases have responded with a >> count in 50% to 70% of the time of the commercial product, in spite of the >> fact that the commercial product does a scan of a non- clustered index while >> PostgreSQL scans the data pages. > > I take it these are fairly narrow rows? The big benefit of index- only scans > come in when you're scanning extremely wide tables, often counting rows > matching some indexed criteria. I'm not sure what you would consider "fairly narrow rows" -- so see the attached. This is the VACUUM ANALYZE VERBOSE output for the largest table, from last night's regular maintenance run. -Kevin --=__Part3D1F8DEC.1__= Content-Type: application/octet-stream; name="CaseHist-vacuum-analyze.txt" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="CaseHist-vacuum-analyze.txt" SU5GTzogIHZhY3V1bWluZyAicHVibGljLkNhc2VIaXN0IgpJTkZPOiAgaW5kZXggIkNhc2VIaXN0 X3BrZXkiIG5vdyBjb250YWlucyAxMzE4NTc0NTggcm93IHZlcnNpb25zIGluIDY2NjY1NiBwYWdl cwpERVRBSUw6ICAxMDIyNCBpbmRleCByb3cgdmVyc2lvbnMgd2VyZSByZW1vdmVkLgowIGluZGV4 IHBhZ2VzIGhhdmUgYmVlbiBkZWxldGVkLCAwIGFyZSBjdXJyZW50bHkgcmV1c2FibGUuCkNQVSA2 MS44MXMvNjEuODd1IHNlYyBlbGFwc2VkIDk0Ni4xNyBzZWMuCklORk86ICBpbmRleCAiQ2FzZUhp c3RfQ2FzZUhpc3RDaWJScHQiIG5vdyBjb250YWlucyAxMzE4NTc0NTggcm93IHZlcnNpb25zIGlu IDgwODQ0MCBwYWdlcwpERVRBSUw6ICAxMDIyNCBpbmRleCByb3cgdmVyc2lvbnMgd2VyZSByZW1v dmVkLgowIGluZGV4IHBhZ2VzIGhhdmUgYmVlbiBkZWxldGVkLCAwIGFyZSBjdXJyZW50bHkgcmV1 c2FibGUuCkNQVSA1NC4zNXMvNjEuNzN1IHNlYyBlbGFwc2VkIDcyNS44OSBzZWMuCklORk86ICAi Q2FzZUhpc3QiOiByZW1vdmVkIDEwMjI0IHJvdyB2ZXJzaW9ucyBpbiA0MTU2IHBhZ2VzCkRFVEFJ TDogIENQVSAwLjY0cy8wLjMydSBzZWMgZWxhcHNlZCAyMy44NSBzZWMuCklORk86ICAiQ2FzZUhp c3QiOiBmb3VuZCAxMDIyNCByZW1vdmFibGUsIDEzMTg1NzQ1OCBub25yZW1vdmFibGUgcm93IHZl cnNpb25zIGluIDI1OTAzODAgcGFnZXMKREVUQUlMOiAgMCBkZWFkIHJvdyB2ZXJzaW9ucyBjYW5u b3QgYmUgcmVtb3ZlZCB5ZXQuClRoZXJlIHdlcmUgODEyOTEgdW51c2VkIGl0ZW0gcG9pbnRlcnMu CjAgcGFnZXMgYXJlIGVudGlyZWx5IGVtcHR5LgpDUFUgMTY0Ljc1cy8xNDEuNTR1IHNlYyBlbGFw c2VkIDIzMjYuOTIgc2VjLgpJTkZPOiAgdmFjdXVtaW5nICJwZ190b2FzdC5wZ190b2FzdF8yNDU4 OCIKSU5GTzogIGluZGV4ICJwZ190b2FzdF8yNDU4OF9pbmRleCIgbm93IGNvbnRhaW5zIDExNiBy b3cgdmVyc2lvbnMgaW4gMiBwYWdlcwpERVRBSUw6ICAwIGluZGV4IHBhZ2VzIGhhdmUgYmVlbiBk ZWxldGVkLCAwIGFyZSBjdXJyZW50bHkgcmV1c2FibGUuCkNQVSAwLjAwcy8wLjAwdSBzZWMgZWxh cHNlZCAwLjAwIHNlYy4KSU5GTzogICJwZ190b2FzdF8yNDU4OCI6IGZvdW5kIDAgcmVtb3ZhYmxl LCAxMTYgbm9ucmVtb3ZhYmxlIHJvdyB2ZXJzaW9ucyBpbiAyNSBwYWdlcwpERVRBSUw6ICAwIGRl YWQgcm93IHZlcnNpb25zIGNhbm5vdCBiZSByZW1vdmVkIHlldC4KVGhlcmUgd2VyZSAzIHVudXNl ZCBpdGVtIHBvaW50ZXJzLgowIHBhZ2VzIGFyZSBlbnRpcmVseSBlbXB0eS4KQ1BVIDAuMDBzLzAu MDB1IHNlYyBlbGFwc2VkIDAuMDEgc2VjLgpJTkZPOiAgYW5hbHl6aW5nICJwdWJsaWMuQ2FzZUhp c3QiCklORk86ICAiQ2FzZUhpc3QiOiBzY2FubmVkIDMwMDAgb2YgMjU5MDM4MCBwYWdlcywgY29u dGFpbmluZyAxNTMxNTYgbGl2ZSByb3dzIGFuZCAwIGRlYWQgcm93czsgMzAwMCByb3dzIGluIHNh bXBsZSwgMTMyMjQ0MDgwIGVzdGltYXRlZCB0b3RhbCByb3dzCg== --=__Part3D1F8DEC.1__=--