Received: from localhost (unknown [200.46.204.184]) by postgresql.org (Postfix) with ESMTP id 44AC89FB42E for ; Fri, 12 Oct 2007 19:51:11 -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 67467-01 for ; Fri, 12 Oct 2007 19:51:00 -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 D7B8B9F9D49 for ; Fri, 12 Oct 2007 19:51:05 -0300 (ADT) Received: from sss2.sss.pgh.pa.us (tgl@localhost [127.0.0.1]) by sss.pgh.pa.us (8.14.1/8.14.1) with ESMTP id l9CMp32Q006276; Fri, 12 Oct 2007 18:51:03 -0400 (EDT) To: henk de wit cc: "pgsql-performance@postgresql.org" Subject: Re: How to speed up min/max(id) in 50M rows table? In-reply-to: References: <5754.1192226626@sss.pgh.pa.us> Comments: In-reply-to henk de wit message dated "Sat, 13 Oct 2007 00:21:26 +0200" Date: Fri, 12 Oct 2007 18:51:03 -0400 Message-ID: <6275.1192229463@sss.pgh.pa.us> From: Tom Lane X-Virus-Scanned: Maia Mailguard 1.0.1 X-Archive-Number: 200710/163 X-Sequence-Number: 27185 henk de wit writes: > I see, that sounds very interesting too. As you might have noticed, I'm not= > an expert on this field but I'm trying to learn. I was under the impressio= > n that the last few incarnations of postgresql automatically combined singl= > e column indexes for cases where a multi-column index would be needed in ea= > rlier releases. It's possible to combine independent indexes for resolving AND-type queries, but the combination process does not preserve ordering, so it's useless for this type of situation. regards, tom lane