Ð ÐÑÑ, 17.08.2004, Ð 17:06, Stephan Szabo ÐÐÑÐÑ: > On Tue, 17 Aug 2004, Markus Bertheau wrote: > > > Ð ÐÑÑ, 17.08.2004, Ð 16:46, Tom Lane ÐÐÑÐÑ: > > > > > I think one reason for this is that otherwise it's not clear which > > > unique constraint the FK constraint depends on. Consider > > > > > > create table a (f1 int unique, f2 int unique); > > > > > > create table b (f1 int, f2 int, > > > foreign key (f1,f2) references a(f1,f2)); > > > > > > How would you decide which constraint to make the FK depend on? > > > > Either way, the semantics are the same, right? > > Unfortunately, not in the case of dropping the chosen constraint.
Can't you choose at fk check time rather than fk creation time? > Theoretically in that case, you'd probably have to extend the spec there > as well to say that you check any dependent objects again to see if they > would still be valid rather than dropping them (on cascade) or erroring > (on restrict). That also makes sense and is more efficient as I see it. Thanks -- Markus Bertheau <[EMAIL PROTECTED]> ---------------------------(end of broadcast)--------------------------- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
