Re: Why doesn't the SERIAL data type automatically have a

Jim C. Nasby wrote:
>>>>Is there some reason why the SERIAL data type doesn't automatically have 
>>>>a UNIQUE CONSTRAINT.
>>>
>>>It used to, and then we decoupled it.
[snip]
> Arguably it would have been better to make the default case add either
> UNIQUE or PRIMARY KEY with a way to over-ride.

Arguably SERIAL shouldn't be a type at all since it's nothing to do with 
defining a set of values. If you were being clean about it you'd have to 
have something like "mycol INTEGER SERIAL UNIQUE", then wire SERIAL to a 
generator function for the type in question.

> If newbies are getting burned maybe it would be useful to toss a NOTICE
> or maybe even WARNING when a serial is created without a unique
> constraint of some kind?

Don't forget the NOT NULL too. Perhaps simpler to have a PGIDENT 
pseudo-type that implies "UNIQUE NOT NULL" and then explain the 
difference in the docs.

--  Richard Huxton  Archonet Ltd