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 6444B9DC9A5 for ; Wed, 11 Jan 2006 05:18:43 -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 31791-01 for ; Wed, 11 Jan 2006 05:18:43 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- Received: from opteron.random (217-133-42-200.b2b.tiscali.it [217.133.42.200]) by postgresql.org (Postfix) with ESMTP id 599AE9DC9A4 for ; Wed, 11 Jan 2006 05:18:40 -0400 (AST) Received: by opteron.random (Postfix, from userid 500) id 687871C18DD; Wed, 11 Jan 2006 10:18:41 +0100 (CET) Date: Wed, 11 Jan 2006 10:18:41 +0100 From: Andrea Arcangeli To: Simon Riggs Cc: Tom Lane , Matteo Beccati , pgsql-performance@postgresql.org Subject: Re: NOT LIKE much faster than LIKE? Message-ID: <20060111091841.GA15897@opteron.random> References: <24021.1136858688@sss.pgh.pa.us> <20060110022303.GA20168@opteron.random> <24372.1136861684@sss.pgh.pa.us> <43C3799D.5030103@beccati.com> <1625.1136915395@sss.pgh.pa.us> <1136930796.21025.486.camel@localhost.localdomain> <6398.1136931685@sss.pgh.pa.us> <1136936205.21025.507.camel@localhost.localdomain> <7924.1136950830@sss.pgh.pa.us> <1136970465.21025.527.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1136970465.21025.527.camel@localhost.localdomain> X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0.12 required=5 tests=[AWL=0.120] X-Spam-Score: 0.12 X-Spam-Level: X-Archive-Number: 200601/106 X-Sequence-Number: 16584 On Wed, Jan 11, 2006 at 09:07:45AM +0000, Simon Riggs wrote: > I would suggest we do this only when all of these are true > - when accessing more than one table, so the selectivity could effect a > join result FWIW my problem only happens if I join: on the main table where the kernel_version string is stored (without joins), everything is always blazing fast. So this requirement certainly sounds fine to me.