On 2017-10-08 17:11:44 -0400, Tom Lane wrote: > Andres Freund <and...@anarazel.de> writes: > > On 2017-10-08 11:28:09 -0400, Tom Lane wrote: > >> https://commitfest.postgresql.org/15/1001/ > >> The reason that's not in v10 is we haven't been able to convince > >> ourselves whether it's 100% correct. > > > Unfortunately it won't help in this specific case (no support for UNION, > > just UNION ALL), but I thought it might be interesting to reference > > https://medium.com/@uwdb/introducing-cosette-527898504bd6 > > here. > > Huh, that is an interesting project indeed. Although I'm not sure that > it quite addresses the question of whether an optimization transform > is valid. IIUC, it could prove that a particular query having been fed > through the transform didn't change semantics, but that offers only > limited insight into whether some other query fed through the transform > might change.
According to the guide it offers some support for more general transformations: http://cosette.cs.washington.edu/guide#24-symbolic-predicates That's still only going to be sufficient for some of the interesting cases, but still... Wonder about pinging them about the OR -> UNION case, they've been responsive to problem in some threads I found online. Greetings, Andres Freund -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
