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. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers