From: Shaun Thomas <sthomas@peak6.com>
To: Nikolas Everett <nik9000@gmail.com>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: Best way to get the latest revision from a table
Date: Fri, 14 Jan 2011 17:06:48 -0600
Message-ID: <4D30D708.3020704@peak6.com> (raw)
In-Reply-To: <AANLkTikVZG_Us9R9iLdz=GnqqEnHE5D7Go9xkENkdGiQ@mail.gmail.com>
References: <AANLkTikVZG_Us9R9iLdz=GnqqEnHE5D7Go9xkENkdGiQ@mail.gmail.com>
On 01/14/2011 03:17 PM, Nikolas Everett wrote:
> SELECT *
> FROM request
> JOIN (SELECT a, MAX(b) as b FROM test GROUP BY a) max USING (a)
> JOIN test USING (a, b);
This actually looks like a perfect candidate for DISTINCT ON.
SELECT DISTINCT ON (a, b) a, b, revision
FROM test
ORDER BY a, b DESC;
Maybe I'm just misunderstanding your situation, though.
--
Shaun Thomas
OptionsHouse | 141 W. Jackson Blvd. | Suite 800 | Chicago IL, 60604
312-676-8870
sthomas@peak6.com
______________________________________________
See http://www.peak6.com/email_disclaimer.php
for terms and conditions related to this email
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: sthomas@peak6.com, nik9000@gmail.com
Subject: Re: Best way to get the latest revision from a table
In-Reply-To: <4D30D708.3020704@peak6.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox