Alex Solovey <a(dot)solovey(at)gmail(dot)com> writes:
> Thanks for the patch. We've tried it here, and it improved query plan
> slightly (indeed, it looks exactly like the plan from 8.2.6 now).
> But, as you've said, empty sub-joins are still not discarded, so query
> execution time did not improve. And this is the same in both 8.2 and 8.3.
If you're feeling brave, try the patch I just committed to CVS.
regards, tom lane