On Mon, 2002-08-19 at 15:42, Curt Sampson wrote: > > A local constraint should be made obvious from looking at the schema, > > Ok, this now I could live with. Though I'm not sure that its > theoretically very defensible, or worth the effort. Other languages > that offer constraints, such as Eiffel (and soon Java), do not allow > constraints that are not inherited, as far as I know. Do you have some > counterexamples.
In Eiffel, at least, I can say "invariant feature_x" and redefine feature_x in a descendant class, thus effectively redefining the constraint. If we decide to inherit constraints unconditionally, the application writer can achieve similar flexibility by moving the logic of the constraint into a function whose behaviour depends on which table it is used on. This would put the burden on the application rather than requiring additional syntax in PostgreSQL. -- Oliver Elphick [EMAIL PROTECTED] Isle of Wight, UK http://www.lfix.co.uk/oliver GPG: 1024D/3E1D0C1C: CA12 09E0 E8D5 8870 5839 932A 614D 4C34 3E1D 0C1C ======================================== "For every one that asketh receiveth; and he that seeketh findeth; and to him that knocketh it shall be opened." Luke 11:10 ---------------------------(end of broadcast)--------------------------- TIP 2: you can get off all lists at once with the unregister command (send "unregister YourEmailAddressHere" to [EMAIL PROTECTED])
