Re: BUG #17975: Nested Loop Index Scan returning wrong result

David Rowley <dgrowleyml(at)gmail(dot)com> writes:
> On Thu, 15 Jun 2023 at 12:28, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> I concur that we'd better just not use partial indexes in
>> relation_has_unique_index_for.

> I wonder if that's ok for a backpatch. This affects both left join
> removals and unique joins. Seems like suddenly making a left join
> removal not work might cause someone some pain.

I kind of doubt that this will affect any large number of users.
If it did, we'd have had reports sooner.

> Is it worth trying to jam in a new boolean field into IndexOptInfo
> into some spare padding to that we run predicate_implied_by() just
> using baserestrictinfo and use those in
> relation_has_unique_index_for()?

How will that work with the caching in innerrel_is_unique?
I also seriously doubt that we can make such a thing work
without adding parameters to any externally-visible functions.

regards, tom lane