Re: feature requests (possibly interested in working on this): functional foreign keys

Chris Travers <chris.travers@gmail.com> writes:
> What would be nice to be able to do is to be able to do something like:
> ALTER TABLE inet_assignment ADD FOREIGN KEY (network(inet_address))
> REFERENCES cidr_block(block_def);

> 2.  Are there any other major showstoppers I haven't thought of?

The information_schema can't represent such a thing, and this is
unfixable without breaking the SQL standard.  I suppose we could omit
functional FK constraints from the information_schema views, but that's
not terribly palatable.

Have you considered just storing the network(inet_address) value in a
separate column (maintained by a BEFORE INSERT/UPDATE trigger) and then
using a regular FK with that?

            regards, tom lane