Re: About unsigned smallint?

On 7/6/05, Ying Lu <ying_lu@cs.concordia.ca> wrote:
> Greetings,
>
> Can I know whether postgreSQL 8.0 supports unsigned smallint please? I
> looked at the doc, it seems that OID is unsigned interger. While I was
> trying to create a simple table as:
>       create table test (id unsigned smallint);
>                              or
>       create table test (id smallint unsigned);
>
> It seems that postgreSQL did not support unsigned integer?

Well, PostgreSQL doesn't have "unsigned" types, unless you create
your own.  If you want to have unsigned type, you can add a check
constraint or, even better, create a domain:

CREATE DOMAIN usmallint AS smallint CHECK (VALUE >= 0);

...while this gives you unsinged smallint type, its probably not
what you wanted.  If you wanted a type which takes two bytes of
storage and stores values from 0 to 65535 then, well... its not it.

If you ask here, you'll probably get a good explanation why there
aren't unsinged types.  My guess is that unsigned types add
complexity which is not really judged by their usefullness, but
thats only a guess.

If you need unsigned-like type for data consistency reasons, just
CREATE DOMAIN as shown above.

  Regards,
      Dawid