Re: strange IS NULL behaviour

On Tue, Sep 3, 2013 at 10:27:38PM -0400, Tom Lane wrote:
> I wrote:
> > And I will say once more that a patch that affects only the behavior of
> > eval_const_expressions can be rejected on its face. That code has to be
> > kept in sync with the behavior of execQual.c, not just whacked around by
> > itself. And then there are the NOT NULL constraint cases to worry about.
>
> Hmm ... actually, it's already not in sync, because:
>
> regression=# create table tt (x int);
> CREATE TABLE
> regression=# insert into tt values(null);
> INSERT 0 1
> regression=# select row(x) from tt;
> row
> -----
> ()
> (1 row)
>
> regression=# select row(row(x)) from tt;
> row
> --------
> ("()")
> (1 row)
>
> regression=# select row(row(row(x))) from tt;
> row
> --------------
> ("(""()"")")
> (1 row)

Uh, I see the same output you show for a NULL constant:

SELECT ROW(NULL);
row
-----
()

SELECT ROW(ROW(NULL));
row
--------
("()")

SELECT ROW(ROW(ROW(NULL)));
row
--------------
("(""()"")")

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

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