Re: Tying an object's ownership to datdba

A cfbot failure showed I had missed ORDER BY in some test queries.

On Sun, Dec 27, 2020 at 08:31:48PM -0800, Noah Misch wrote:
> I ended up blocking DDL that creates role memberships involving the new role;
> see reasons in user.c comments. Lifting those restrictions looked feasible,
> but it was inessential to the mission, and avoiding unintended consequences
> would have been tricky.

Later, I pondered the case of pg_database_owner owning a shared object
(database or tablespace). The behavior is certainly odd. For a tablespace,
any database owner can act as the tablespace owner (but only when connected to
a database that the role owns). For a database, likewise. When connected to
a database having datdba=pg_database_owner, no particular role acts as the
owner, just superusers and SECURITY DEFINER functions owned by
pg_database_owner. I don't have high hopes for that being useful, but I
couldn't quite convince myself to ban it. Attached v2 does expand an
AddRoleMems() comment to discuss this, though.