From: Tom Lane <tgl@sss.pgh.pa.us>
To: Claudio Freire <klaussfreire@gmail.com>
cc: Robert DiFalco <robert.difalco@gmail.com>,
 "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Subject: Re: Efficiently query for the most recent record for a given user
In-reply-to: 
 <CAGTBQpY5pDZBgpo+huLzUpi6zve69V7KKWUVeLaSBpr6ZvOLwQ@mail.gmail.com>
References: 
 <CAAXGW-yF4urbcPHRj2DwcmkzE66DeJfKQQ+sTmZX-BD_FXKecw@mail.gmail.com>
 <CAGTBQpY5pDZBgpo+huLzUpi6zve69V7KKWUVeLaSBpr6ZvOLwQ@mail.gmail.com>
Comments: In-reply-to Claudio Freire <klaussfreire@gmail.com>
 message dated "Wed, 07 Aug 2013 15:19:32 -0300"
Date: Wed, 07 Aug 2013 14:34:12 -0400
Message-ID: <9813.1375900452@sss.pgh.pa.us>
Precedence: bulk
Sender: pgsql-performance-owner@postgresql.org

Claudio Freire <klaussfreire@gmail.com> writes:
> On Wed, Aug 7, 2013 at 3:12 PM, Robert DiFalco <robert.difalco@gmail.com> wrote:
>> I want to get the last call_activity record for a single user.

> Create an index over (user_id, called desc), and do
> select * from call_activity where user_id = blarg order by called desc limit 1

Note that there's no particular need to specify "desc" in the index
definition.  This same index can support searches in either direction
on the "called" column.

			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