From: | Bruce Momjian <bruce(at)momjian(dot)us> |
---|---|
To: | Kevin Grittner <kgrittn(at)ymail(dot)com> |
Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Hannu Krosing <hannu(at)2ndquadrant(dot)com>, Peter Eisentraut <peter_e(at)gmx(dot)net>, Andrew Dunstan <andrew(at)dunslane(dot)net>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: strange IS NULL behaviour |
Date: | 2013-09-10 19:52:00 |
Message-ID: | 20130910195200.GB16378@momjian.us |
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Lists: | pgsql-hackers |
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. +
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