Re: Fix bogus Asserts in calc_non_nestloop_required_outer - Mailing list pgsql-hackers

Robert Haas <robertmhaas@gmail.com> writes:
> On Fri, Jan 5, 2024 at 4:36 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I don't think I believe this code change, let alone any of the
>> explanations for it.  The point of these Asserts is to be sure that
>> we don't form an alleged parameterization set that includes any rels
>> that are included in the new join, because that would be obviously
>> wrong.  They do check that as they stand.  I'm not sure what invariant
>> the proposed revision would be enforcing.

> Well, this explanation made sense to me:
> https://www.postgresql.org/message-id/CAMbWs4-%2BGs0HJ9ouBUb%3DqwHsGCXxG%2B92eJzLOpCkedvgtOWQ%3DQ%40mail.gmail.com

The argument for the patch as proposed is that we should make the
mergejoin and hashjoin code paths do what the nestloop path is doing.
However, as I replied further down in that other thread, I'm not
exactly convinced that the nestloop path is doing the right thing.
I've not had time to look closer at that, though.

            regards, tom lane