Re: Picking out the most recent row using a time stamp column - Mailing list pgsql-performance

> Why did you use row_number instead of rank?

Because I assumed he only wanted one row in the event of ties.

Hmmm, although with that schema, there won't be ties.  So it's pretty
much arbitrary then.

> 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.

Hopefully we'll find out!  The windowing functions are usually much
faster for me.  I think in 9.0 or 9.1 someone replumbed DISTINCT ON to
use a bunch of the window function internals, at which point it'll cease
to matter.

--
                                  -- Josh Berkus
                                     PostgreSQL Experts Inc.
                                     http://www.pgexperts.com