Re: INSERT ... ON CONFLICT UPDATE/IGNORE 4.0

On 2015-05-20 11:24:06 -0700, Peter Geoghegan wrote:
> On Wed, May 20, 2015 at 10:37 AM, Andres Freund <andres@anarazel.de> wrote:
> > But you *can* use a exclusion constraint for DO NOTHING. Just not (yet)
> > for DO UPDATE.
> 
> FWIW, I don't think exclusion constraint DO UPDATE support is ever
> going to be useful.

Why?

Even if maybe not directly under the guise of exclusion constraints
themselves, but I do think it's an interesting way to more easily allow
to implement unique constraints on !amcanunique type indexes.  Or, more
interestingly, for unique keys spanning partitions.