Re: Unique constraints for non-btree indexes

Tom Lane <tgl@sss.pgh.pa.us> writes:

> Martijn van Oosterhout <kleptog@svana.org> writes:
> > I guess what you're talking about is a constrained index, of which a
> > unique index is just a particular type. I suppose the actual constraint
> > would be one of the operators defined for the operator class (since
> > whatever the test is, it needs to be indexable). Although some would
> > obviously be more useful than others...
> 
> I think the generalization that would be appropriate for GIST is that
> a "unique" index guarantees there are no two entries x, y such that
> x ~ y, where ~ is some boolean operator nominated by the opclass.  We'd
> probably have to insist that ~ is commutative (x ~ y iff y ~ x).

I have no big contribution here. I just want to say this is a cool idea.
These Generalized uniqueish constraints could make a lot of neat things
possible.

-- 
greg