> If we were willing to abuse the ALTER TABLE syntax some more, it would
> be possible to support changing the datatypes of f1 and f2
> simultaneously, thereby allowing the above to work. The infrastructure
> for hacking multiple tables in parallel is already there in CVS tip,
> but it only gets exercised in cases involving inheritance.
I don't think we need to allow end users to do it via the grammar.
Allowing an ALTER TYPE or ALTER DOMAIN to set up the multiple table
transform is enough.