Re: pg17 issues with not-null contraints

On Tue, Apr 16, 2024 at 08:11:49PM +0200, Alvaro Herrera wrote:
> This is still missing some cleanup and additional tests, of course.
> Speaking of which, I wonder if I should modify pg16's tests so that they
> leave behind tables set up in this way, to immortalize pg_upgrade
> testing.

That seems like it could be important.  I considered but never actually
test your patch by pg_upgrading across major versions.

BTW, this works up to v16 (although maybe it should not):

| CREATE TABLE ip(id int PRIMARY KEY); CREATE TABLE ic(id int) INHERITS (ip); ALTER TABLE ic ALTER id DROP NOT NULL;

Under v17, this fails. Maybe that's okay, but it should probably be
called out in the release notes.
| ERROR:  cannot drop inherited constraint "ic_id_not_null" of relation "ic"

That's the issue that I mentioned in the 6 year old thread.  In the
future (upgrading *from* v17) it won't be possible anymore, right?  It'd
still be nice to detect the issue in advance rather than failing halfway
through the upgrade.  I have a rebased patch while I'll send on that
thread.  I guess it's mostly unrelated to your patch but it'd be nice if
you could take a look.

-- 
Justin