> Really, the way to fix Teodor's complaint is to recognize that the
> semijoin inner rel is effectively unique against the whole outer rel,
> and then strength-reduce the semijoin to a plain join. The infrastructure
> we built for unique joins is capable of proving that, we just weren't
> applying it in the right way.
Perfect, it works. Thank you! Second patch reduces time of full query (my
example was just a small part) from 20 minutes to 20 seconds.
> I'm kind of strongly tempted to apply the second patch; but it would
> be fair to complain that reduce_unique_semijoins() is new development
> and should wait for v11. Opinions?
Obviously, I'm voting for second patch applied to version 10.
--
Teodor Sigaev E-mail: teodor@sigaev.ru
WWW: http://www.sigaev.ru/
