Re: Efficiently query for the most recent record for a given user

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Claudio Freire <klaussfreire(at)gmail(dot)com>
Cc: Robert DiFalco <robert(dot)difalco(at)gmail(dot)com>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Efficiently query for the most recent record for a given user
Date: 2013-08-07 18:34:12
Message-ID: 9813.1375900452@sss.pgh.pa.us
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Claudio Freire <klaussfreire(at)gmail(dot)com> writes:
> On Wed, Aug 7, 2013 at 3:12 PM, Robert DiFalco <robert(dot)difalco(at)gmail(dot)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

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