On Mon, 30 Jan 2006, Tom Lane wrote:
> Richard Jones <rich@annexia.org> writes:
>> It doesn't seem to be possible to find out if a parameter or result
>> field is nullable using the Describe protocol.
>
> This isn't something that the backend tracks at all, so changing the
> wire protocol would be the least of your problems in making it happen...
>
Well, the protocol does attempt to return the resulting columns' source
table and column number which may then be used to determine the
nullability of the field. This won't work in all cases, but for the
simple select example given, it will.
Kris Jurka