| From: | Shaun Thomas <sthomas(at)peak6(dot)com> |
|---|---|
| To: | Josh Berkus <josh(at)agliodbs(dot)com> |
| Cc: | Dave Crooke <dcrooke(at)gmail(dot)com>, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, Michael Glaesemann <grzm(at)seespotcode(dot)net>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Picking out the most recent row using a time stamp column |
| Date: | 2011-02-25 00:58:33 |
| Message-ID: | 4D66FEB9.6000501@peak6.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-performance |
On 02/24/2011 06:20 PM, Josh Berkus wrote:
> SELECT id_key, time_stamp, value
> FROM (
> SELECT id_key, time_stamp, value,
> row_number()
> OVER ( PARTITION BY id_key
> ORDER BY time_stamp DESC)
> as ranking
> FROM thetable
> ) as filtered_table
> WHERE ranking = 1
Why did you use row_number instead of rank?
I am now curious how the speed compares though. I still think the
DISTINCT ON will be faster, but it would be a great surprise.
--
Shaun Thomas
OptionsHouse | 141 W. Jackson Blvd. | Suite 800 | Chicago IL, 60604
312-676-8870
sthomas(at)peak6(dot)com
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