Re: Picking out the most recent row using a time stamp column

Thanks to all .... I had a tickling feeling at the back of my mind that
there was a neater answer here. For the record, times (all from in-memory
cached data, averaged over a bunch of runs):

Dependent subquery = 117.9 seconds
Join to temp table = 2.7 sec
DISTINCT ON = 2.7 sec

So the DISTINCT ON may not be quicker, but it sure is tidier.

Cheers
Dave

On Thu, Feb 24, 2011 at 2:24 PM, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov
> wrote:

> Michael Glaesemann <grzm(at)seespotcode(dot)net> wrote:
>
> > SELECT DISTINCT ON (data.id_key)
> > data.id_key, data.time_stamp, data.value
> > FROM data
> > ORDER BY data.id_key, data.time_stamp DESC;
>
> Dang! I forgot the DESC in my post! Thanks for showing the
> *correct* version.
>
> -Kevin
>