Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> You know, I've never really understood the difference between these
> two types of things, or why we need to support both. Which may be
> just because I'm slow?
Unique constraints are defined by the SQL standard, and have a syntax
that can't support a lot of the extensions that CREATE INDEX allows.
There's also restrictions in the information_schema views.
So unifying the two concepts completely would be a mess.
regards, tom lane