Re: strange IS NULL behaviour

On Tue, Sep 10, 2013 at 12:48:08PM -0700, Kevin Grittner wrote:
> Bruce Momjian <bruce(at)momjian(dot)us> wrote:
>
> > FYI, I think these queries below prove that NOT NULL constraints do not
> > follow the single-depth ROW NULL inspection rule that PL/pgSQL follows,
> > and that my patch was trying to promote for queries:
> >
> >     CREATE TABLE test2(x test NOT NULL);
> >     CREATE TABLE
> >     INSERT INTO test2 VALUES (null);
> >     ERROR:  null value in column "x" violates not-null constraint
> >     DETAIL:  Failing row contains (null).
> > -->    INSERT INTO test2 VALUES (row(null));
> >     INSERT 0 1
>
> If I remember correctly, the standard wants a NOT NULL constraint
> on a column with a composite type to behave the same as
>
>   CHECK (col IS DISTINCT FROM NULL)
>
> ... which is consistent with the behavior you show.

Is IS DISTINCT FROM correct though?

SELECT ROW(NULL) IS DISTINCT FROM NULL;
?column?
----------
t
(1 row)

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ It's impossible for everything to be true. +