On Tue, Apr 9, 2024 at 8:37 AM Andrei Lepikhov <a.lepik...@postgrespro.ru> wrote: > On 9/4/2024 09:12, Tom Lane wrote: > > I have another one that I'm not terribly happy about: > > > > Author: Alexander Korotkov <akorot...@postgresql.org> > > Branch: master [72bd38cc9] 2024-04-08 01:27:52 +0300 > > > > Transform OR clauses to ANY expression > Because I'm primary author of the idea, let me answer. > > > > I don't know that I'd call it scary exactly, but I do think it > > was premature. A week ago there was no consensus that it was > > ready to commit, but Alexander pushed it (or half of it, anyway) > > despite that. A few concrete concerns: > > > > * Yet another planner GUC. Do we really need or want that? > It is the most interesting question here. Looking around planner > features designed but not applied for the same reason because they can > produce suboptimal plans in corner cases, I think about inventing > flag-type parameters and hiding some features that work better for > different load types under such flagged parameters.
Yes, I have spotted this transformation could cause a bitmap scan plan regressions in [1] and [2]. Fixing that required to treat ANY the same as OR for bitmap scans. Andrei implemented that in [3], but that increases planning complexity and elimitates significant part of the advantages of OR-to-ANY transformation. Links. 1. https://www.postgresql.org/message-id/CAPpHfduJtO0s9E%3DSHUTzrCD88BH0eik0UNog1_q3XBF2wLmH6g%40mail.gmail.com 2. https://www.postgresql.org/message-id/CAPpHfdtSXxhdv3mLOLjEewGeXJ%2BFtfhjqodn1WWuq5JLsKx48g%40mail.gmail.com 3. https://www.postgresql.org/message-id/6d27d752-db0b-4cac-9843-6ba3dd7a1e94%40postgrespro.ru ------ Regards, Alexander Korotkov