Re: Intersection or zero-column queries

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

> On Thu, Dec 21, 2017 at 4:53 PM, Victor Yegorov <vyegorov@gmail.com>
> 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