Re: Document NULL - Mailing list pgsql-hackers

From jian he
Subject Re: Document NULL
Date
Msg-id CACJufxE9q6KsBuPuLtZBdOKd05h048MhhOO3XTtHUx=p4i=VUA@mail.gmail.com
Whole thread Raw
In response to Re: Document NULL  (Laurenz Albe <laurenz.albe@cybertec.at>)
Responses Re: Document NULL
List pgsql-hackers
On Fri, May 3, 2024 at 2:47 PM Laurenz Albe <laurenz.albe@cybertec.at> wrote:
>
> On Thu, 2024-05-02 at 08:23 -0700, David G. Johnston wrote:
> > Version 2 attached.  Still a draft, focused on topic picking and overall structure.
>
> I'm fine with most of the material (ignoring ellipses and typos), except this:
>
> +    The NOT NULL column constraint is largely syntax sugar for the corresponding
> +    column IS NOT NULL check constraint, though there are metadata differences
> +    described in create table.
>

the system does not translate (check constraint column IS NOT NULL)
to NOT NULL constraint,
at least in domain.

for example:
create domain connotnull integer;
alter domain connotnull add not null;
\dD connotnull

drop domain connotnull cascade;
create domain connotnull integer;
alter domain connotnull add check (value is not null);
\dD



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