Re: Incorrect handling of IS [NOT] NULL quals on inheritance parents

On Wed, 10 Apr 2024 at 17:18, Tom Lane  wrote:
>
> David Rowley  writes:
> > I think a better fix is just to not apply the optimisation for
> > inheritance RTEs in add_base_clause_to_rel().
>
> Is it worth paying attention to whether the constraint is marked
> connoinherit?  If that involves an extra syscache fetch, I'd tend to
> agree that it's not worth it; but if we can get that info for free
> it seems worthwhile to not break this for inheritance cases.

I think everything should be optimised as we like without that.
Effectively get_relation_info() looks at the pg_attribute.attnotnull
column for the relation in question. We never look at the
pg_constraint record to figure out the nullability of the column.

David