Re: Remove implicit unique index creation on SERIAL

On Sun, 2002-08-18 at 02:35, Joe Conway wrote:
> Tom Lane wrote:
> > Joe Conway <mail@joeconway.com> writes:
> >>I agree 100%. If you want an index, unique constraint, or primary key on 
> >>a SERIAL, I think you should explicitly add it. SERIAL should give me a 
> >>column that automatically increments -- no more, no less.
> > 
> > Hmm, do you also want to eliminate the implicit NOT NULL constraint?
> > 
> > I think that efficiency and orthogonality are adequate reasons for
> > dissociating UNIQUE from SERIAL.  The efficiency argument is pretty
> > weak in the case of the NOT NULL part, though, so maybe backwards
> > compatibility should win out there.
> 
> To be honest I wasn't thinking about NOT NULL. I'd agree with leaving 
> that in place.
> 
> Maybe I should restate my comment above: SERIAL should give me a column 
> that automatically increments -- no more, no less -- and it should not 
> allow me to override the value that it gives. Hence an implicit NOT 
> NULL, but also an implicit rejection of a manual insert/update of that 
> field (how hard would this be to do?).

I don't like not overriding the value.  A dataload example is a perfect
reason why you would want to.  Anyway, this would require placing 2
triggers on the table in order to prevent changes of the value.

Personally I prefer the method that SAPdb uses.  They make the column a
fixed() type (integer) and set the default.  Nothing about NOT NULL or
UNIQUE.

Anyway, I think SERIAL is about assisting creation of a entry, not
enforcing it.  Enforcement is trivial for those who don't mind the
additional overhead.