Re: fdw validation function vs zero catalog id

I wrote:
> The validator is run for the generic options specified to CREATE/ALTER FDW,
> SERVER and USER MAPPING (+ possible future SQL/MED objects). In this case the
> catalog is always known. Also we can assume that the catalog is known, if a user
> runs the validator directly. So yes, AFAICS there is no case for the "or zero".
> 

Updated patch attached. This now also removes the "or zero" note from
the documentation and modifies postgresql_fdw_validator() to assume that
a valid catalog oid is always passed.

regards,
Martin