Received: from malur.postgresql.org ([217.196.149.56])
 by arkaria.postgresql.org with esmtp (Exim 4.80) (envelope-from
 <pgsql-performance-owner+M53084=pgsql-performance-ar@postgresql.org>)
 id 1Yvve4-0001Ht-U7
 for pgsql-performance@arkaria.postgresql.org; Fri, 22 May 2015 22:42:25 +0000
Received: from localhost ([127.0.0.1] helo=postgresql.org)
 by malur.postgresql.org with smtp (Exim 4.80) (envelope-from
 <pgsql-performance-owner+M53084=pgsql-performance-ar@postgresql.org>)
 id 1Yvve4-00045V-Ew
 for pgsql-performance@arkaria.postgresql.org; Fri, 22 May 2015 22:42:24 +0000
Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29])
 by malur.postgresql.org with esmtps (TLS1.2:RSA_AES_256_CBC_SHA256:256)
 (Exim 4.80) (envelope-from <tgl@sss.pgh.pa.us>) id 1Yvve3-00045J-DC
 for pgsql-performance@postgresql.org; Fri, 22 May 2015 22:42:23 +0000
Received: from sss.pgh.pa.us ([66.207.139.130])
 by magus.postgresql.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA384:256)
 (Exim 4.84) (envelope-from <tgl@sss.pgh.pa.us>) id 1Yvve0-0001he-EE
 for pgsql-performance@postgresql.org; Fri, 22 May 2015 22:42:22 +0000
Received: from sss1.sss.pgh.pa.us (localhost [127.0.0.1])
 by sss.pgh.pa.us (8.14.4/8.14.4) with ESMTP id t4MMgGcb017858;
 Fri, 22 May 2015 18:42:16 -0400
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Dave Johansen <davejohansen@gmail.com>
cc: pgsql-performance <pgsql-performance@postgresql.org>
Subject: Re: MAX() and multi-column index on a partitioned table?
In-reply-to: 
 <CAAcYxUe0J55EpVhFnbJo6A6FHizt6NzfhH2dRGHobXKvpTPjzQ@mail.gmail.com>
References: 
 <CAAcYxUe0J55EpVhFnbJo6A6FHizt6NzfhH2dRGHobXKvpTPjzQ@mail.gmail.com>
Comments: In-reply-to Dave Johansen <davejohansen@gmail.com>
 message dated "Fri, 22 May 2015 15:27:29 -0700"
Date: Fri, 22 May 2015 18:42:16 -0400
Message-ID: <17857.1432334536@sss.pgh.pa.us>
X-Pg-Spam-Score: -1.9 (-)
List-Archive: <http://archives.postgresql.org/pgsql-performance>
List-Help: <mailto:majordomo@postgresql.org?body=help>
List-ID: <pgsql-performance.postgresql.org>
List-Owner: <mailto:pgsql-performance-owner@postgresql.org>
List-Post: <mailto:pgsql-performance@postgresql.org>
List-Subscribe: <mailto:majordomo@postgresql.org?body=sub%20pgsql-performance>
List-Unsubscribe: 
 <mailto:majordomo@postgresql.org?body=unsub%20pgsql-performance>
X-Mailing-List: pgsql-performance
Precedence: bulk
Sender: pgsql-performance-owner@postgresql.org

Dave Johansen <davejohansen@gmail.com> writes:
> I'm trying to call MAX() on the first value of a multi-column index of a
> partitioned table and the planner is choosing to do a sequential scan
> instead of an index scan. Is there something I can do to fix this?

What PG version are you using?  9.1 or newer should know how to do this
with a merge append of several indexscans.

			regards, tom lane


-- 
Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance