Re: Autoincrement

(redirected to the SQL list because it really has nothing to do with
interfaces):

At 14:07 +0300 on 17/7/98, Federico Passaro wrote:

> You are right, but it's better to put the autoincrementing field as
> the last one like in:
>
> CREATE TABLE cliente (
> name varchar(100) UNIQUE NOT NULL,
> username varchar(8) NOT NULL ,
> key int4 NOT NULL DEFAULT nextval('key_s') PRIMARY KEY,
> );
>
> This way you can use the sintax
>
> insert into cliente values ('JACK', 'postgres');
>
> in place of
>
> insert into cliente (name, username) values ('JACK', 'postgres');

No! The syntax may look attractive to you, because you have to write less,
but you will pay for it in performance! I definitely would not put that
field last. This is because in the current version of Postgres, any fields
following the first VARCHAR have a performance penalty. So, in order to
avoid this, you should place all fixed-sized fields at the beginning, and
then all the variable-length fields.

In any case it is always recommeded to explicitly specify the names of all
the fields in an insert operation, rather than rely on your memory of the
correct order.

> A more robust solution is to use a trigger. Look at the files
> <PostGreSQL source dir>/contrib/spi/autoinc.*

I am not sure a solution which depends on writing code in C and having
postgres superuser privileges can be considered "more robust". I'd
recommend the use of sequences in any case.

Herouth

--
Herouth Maoz, Internet developer.
Open University of Israel - Telem project
http://telem.openu.ac.il/~herutma