Re: Deferred partial/expression unique constraints

On Fri, 2011-07-22 at 23:35 +0300, Peter Eisentraut wrote:
> On ons, 2011-07-13 at 11:26 -0400, Tom Lane wrote:
> > Our standard reason for not implementing UNIQUE constraints on
> > expressions has been that then you would have a thing that claims to be
> > a UNIQUE constraint but isn't representable in the information_schema
> > views that are supposed to show UNIQUE constraints.  We avoid this
> > objection in the current design by shoving all that functionality into
> > EXCLUDE constraints, which are clearly outside the scope of the spec.
> 
> I have never heard that reason before, and I think it's a pretty poor
> one.  There are a lot of other things that are not representable in the
> information schema.

I think what Tom is saying is that the information_schema might appear
inconsistent to someone following the spec.

Can you give another example where we do something like that?

Regards,Jeff Davis