Re: Intersection or zero-column queries

[Victor Yegorov <vyegorov@xxxxxxxxx>]

2017-12-22 2:03 GMT+02:00 David G. Johnston <david.g.johnston@xxxxxxxxx>:

On Thu, Dec 21, 2017 at 4:53 PM, Victor Yegorov <vyegorov@xxxxxxxxx> wrote:

    postgres=# select except select;

    --

    (2 rows)

    postgres=# select intersect all select;

    --

    (2 rows)

Why is it so?

Should this be reported as a bug?.. ;)

​The intersection case seems correct - one row from each sub-relation is returned since ALL is specified and both results as the same.

Actually, result will not change with or without `ALL` for both, EXCEPT and INTERSECT.

Also, intersection should not return more rows, than there're in the sub-relations.

--

Victor Yegorov