On Fri, 2002-09-13 at 04:27, Christopher Kings-Lynne wrote:
> > AFAIK, the extra index only slows down my inserts - it basically contains
> > no usable information...
>
> Not 100% true. It will speed up cascade delete and update...
>
> > shouldn't the presence of _primary_key_ in
> > multicol foreign key be enough to decide whether the whole key is unique
> > or not?
>
> Hmmm - thinking about it, I don't see why postgres would need the entire
> thing to be unique...can't think of a reason at the moment. Stephen?
If it's not all unique, you cannot be guaranteed there is a single row
with those values in the referenced table.
-- Rod Taylor