In terms of making constraints more declarative, I think it would be neat to
add an extra field to pg_relcheck that is a foreign key (or null) into the
pg_attribute table.
That way, it would be possible to recover column CHECK constraints. If the
field is NULL, you'd assume it was a table CHECK constraint...
Theoretically, it would mean that less information is 'lost' after the table
creation.
Chris
