Re: Improving non-joinable EXISTS subqueries

* Tom Lane (tgl@sss.pgh.pa.us) wrote:
> So ... I'm wondering if this actually touches anyone's hot-button,
> or if we should just file it in the overflowing pile of Things That
> Might Be Nice To Do Someday.

What bugs me the most about having IN() be faster than EXISTS() in
certain situations is that it ends up being counter-intuitive and not
really what you'd expect to happen.  That being said, we can always tell
people that they can use IN() as a work-around for these situations.  In
the long run, I think it's definitely worth it to spend a bit of extra
time in planning the query for this case.  Not knowing what else is on
your plate for 8.4, I don't know where I'd rank this, but it wouldn't be
at the top.
Thanks,
    Stephen