Re: Grabbing Newest Records From Duplicates

One last question, using the "weather report" example, is it going to
improve performance for the DISTINCT ON query to add an index to the
location and time columns?

Thanks a lot,
Travis

On 3/16/07, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> "Travis Whitton" <tinymountain(at)gmail(dot)com> writes:
> > Given the following test table, I want to grab only the newest record
> and
> > disregard any older duplicates based on name. Is this the most efficient
> way
> > to do it?
>
> No, it's gonna be pretty awful. The best way I know of involves
> DISTINCT ON (see the "weather reports" example in the SELECT reference
> page). Unfortunately that's a Postgres-only construct. If you want
> something portable then you'll need something messy with subqueries...
>
> regards, tom lane
>