Greg Stark <gsstark(at)mit(dot)edu> writes:
> This could hurt if they ever reuse an old previously retired postal code,
> which isn't an entirely impossible case. As far as I know it hasn't happened
> yet though.
One would suppose that the guys who are in charge of this point at
Canada Post consider the postal code to be their primary key, and
are no more eager to reuse one than you are to see it reused.
Basically this comes down to "I'm going to use some externally supplied
primary key as my primary key. Do I trust the upstream DBA to know what
a primary key is?"
regards, tom lane