On Tue, 2015-08-25 at 20:17 -0400, Melvin Davidson wrote:
> I think a lot of people here are missing the point. I was trying to
> give examples of natural keys, but a lot of people are taking great
> delight
> in pointing out exceptions to examples, rather than understanding the
> point.
> So for the sake of argument, a natural key is something that in
> itself is unique and the possibility of a duplicate does not exist.
> Before ANYONE continues to insist that a serial id column is good,
> consider the case where the number of tuples will exceed a bigint.
> Don't say it cannot happen, because it can.
> However, if you have an alphanumeric field, let's say varchar 50, and
> it's guaranteed that it will never have a duplicate, then THAT is a
> natural primary
> key and beats the hell out of a generic "id" field.
>
> Further to the point, since I started this thread, I am holding to it
> and will not discuss "natural primary keys" any further.
>
> Other suggestions for good PostgreSQL Developer database (not web
> app) guidelines are still welcome.
>
Funny how Melvin's attempt to bring order to the chaos ended up as a
discussion about primary keys.
We once hired a "genius" to design an application to handle fixed
assets. Every table had a primary key named "id". Some were integer and
some were character. So the foreign key columns in child tables had to
be named differently. Writing the joins was complex.
I also know of an airline reservation system where you are unable to
alter your e-mail address. It apparently needs a DBA type person to
make the change. I can only guess that your e-mail address is used as a
foreign key in one or more tables. As well as assigning you a frequent
flyer number they also assign another integer identifier. A bit of
common sense goes a long way when designing an application.
Cheers,
rob