Stéphane Schildknecht <stephane.schildknecht@postgresqlfr.org> writes:
> It seems the shell command createuser and the SQL CREATE USER don't act
> the same way,
They aren't really claimed to. But the difference you point to is
irrelevant, since a superuser has createrole and createdb privilege
(and every other privilege) independently of what those columns say.
regards, tom lane
