RObert,
> I guess I'm going to have to vote -1 on this proposal. I code see
> inventing a pgsql-specific SQLSTATE value for exclusion constraints,
> since they will be a pgsql-specific extension, but reusing the unique
> key violation value seems misleading. I admit it may help in a
> limited number of cases, but IMHO it's not worth the confusion.
I'd rather have a new one than just using "contstraint violation" which
is terribly non-specific, and generally makes the application developer
think that a value is too large.
--Josh BErkus