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 1867C9DC803 for ; Thu, 12 Jan 2006 11:53:55 -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 65050-08 for ; Thu, 12 Jan 2006 11:53:59 -0400 (AST) X-Greylist: from auto-whitelisted by SQLgrey- Received: from sss.pgh.pa.us (sss.pgh.pa.us [66.207.139.130]) by postgresql.org (Postfix) with ESMTP id 0AA7C9DC81D for ; Thu, 12 Jan 2006 11:53:50 -0400 (AST) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.13.1/8.13.1) with ESMTP id k0CFrrt4005270; Thu, 12 Jan 2006 10:53:53 -0500 (EST) To: =?ISO-8859-1?Q?Ott=F3_Havasv=F6lgyi?= cc: pgsql-performance@postgresql.org Subject: Re: Throwing unnecessary joins away In-reply-to: <34608c0c0601120541wd910da3s@mail.gmail.com> References: <34608c0c0601120418n1af567b9n@mail.gmail.com> <43C64CFB.9030504@barettadeit.com> <34608c0c0601120541wd910da3s@mail.gmail.com> Comments: In-reply-to =?ISO-8859-1?Q?Ott=F3_Havasv=F6lgyi?= message dated "Thu, 12 Jan 2006 14:41:30 +0100" Date: Thu, 12 Jan 2006 10:53:53 -0500 Message-ID: <5269.1137081233@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: by amavisd-new at hub.org X-Spam-Status: No, score=0.086 required=5 tests=[AWL=0.086] X-Spam-Score: 0.086 X-Spam-Level: X-Archive-Number: 200601/156 X-Sequence-Number: 16634 =?ISO-8859-1?Q?Ott=F3_Havasv=F6lgyi?= writes: > As far as I know SQL Server has some similar feature. It does not join > if not necessary, more exactly: if the result would be the same if it > joined the table. I find it really really hard to believe that such cases arise often enough to justify having the planner spend cycles checking for them. regards, tom lane