"Chris Travers" <chris@travelamericas.com> writes:
> The MySQL manual states that Joins perform better than subselects.
Very possibly true ... in MySQL. Since they have such an immature
subselect implementation (not even out of alpha apparently), it'd
not be surprising if they can't optimize subselects worth a damn yet.
Our planner has been hacked on repeatedly to do a good job with
subselects --- and I wouldn't want to imply that the process is done
yet.
One of the more amusing aspects of watching MySQL's response to the
"feature race" is how they invariably gloss over the difference between
having a minimal implementation of a feature, and having a feature that
is mature, complete, and efficient. Subselects are one example where
there's a lot of mileage yet to cover after you get to the point where
you can say "it works".
regards, tom lane
