"Bjoern A. Zeeb" <bzeeb-lists(at)lists(dot)zabbadoz(dot)net> writes:
> Is this correct or is it just a "works like that this time but may
> change at any time in the future"?
The meaning of a NULL for a composite value isn't real well-defined
at the moment. I tend to agree that "fbt IS NULL" should yield true
in your example, but I think there are/were some implementation reasons
why it doesn't.
regards, tom lane