Received: from localhost (unknown [200.46.204.184]) by postgresql.org (Postfix) with ESMTP id F03062E0267 for ; Tue, 18 Mar 2008 11:49:43 -0300 (ADT) Received: from postgresql.org ([200.46.204.71]) by localhost (mx1.hub.org [200.46.204.184]) (amavisd-maia, port 10024) with ESMTP id 01786-09 for ; Tue, 18 Mar 2008 11:49:26 -0300 (ADT) X-Greylist: from auto-whitelisted by SQLgrey-1.7.5 Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by postgresql.org (Postfix) with ESMTP id BB8302E0274 for ; Tue, 18 Mar 2008 11:49:34 -0300 (ADT) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.14.2/8.14.2) with ESMTP id m2IEnWhd025025; Tue, 18 Mar 2008 10:49:32 -0400 (EDT) To: Ron Mayer cc: Bruce Momjian , pgsql-performance@postgresql.org Subject: Re: TB-sized databases In-reply-to: <47DF57B3.9090206@cheapcomplexdevices.com> References: <200803172347.m2HNlCD29489@momjian.us> <4005.1205800130@sss.pgh.pa.us> <47DF57B3.9090206@cheapcomplexdevices.com> Comments: In-reply-to Ron Mayer message dated "Mon, 17 Mar 2008 22:48:35 -0700" Date: Tue, 18 Mar 2008 10:49:32 -0400 Message-ID: <25024.1205851772@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200803/370 X-Sequence-Number: 29324 Ron Mayer writes: > Would another possible condition for considering > Cartesian joins be be: > * Consider Cartesian joins when a unique constraint can prove > that at most one row will be pulled from one of the tables > that would be part of this join? What for? That would still lead us to consider large numbers of totally useless joins. regards, tom lane