Re: Is a SERIAL column a "black box", or not?

Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> My idea is to create a new SECURITY DEFINER function called
> serial_nextval(), and use that for SERIAL defaults.

You haven't thought about this at all. Who will own that function?
Surely we don't want to create a new one for every SERIAL column.
And even if we did, what magic will cause its ownership to change
when the table's owner is changed?

I'm leaning towards the idea that we need special syntax, along the
lines of
DEFAULT nextval('some_seq') AS OWNER
which would result in generating a special expression node type at
the time the DEFAULT expression is inserted into a query plan (and
no earlier). At runtime this node would temporarily switch
current_user, just as we do for SECURITY_DEFINER functions --- but by
postponing the determination of which user to switch to until the plan
is built, we avoid trouble with ALTER TABLE OWNER.

Per Bruno's earlier comments, we probably need the same feature for
table CHECK constraints. Might be interesting to think about it for
domain check constraints too, though that's getting a bit far afield
unless someone has a convincing use-case.

regards, tom lane