How to count distinct on a group by hstore key with join?

Question

I'm trying to do the following with postgres:

• count distinct
• table joins
• group by hstore key

I don't think I'm too far, but the count distinct isn't added up per group by values.

Here is the code on rextester.com

What I have so far:

SELECT COUNT(DISTINCT pets.id),locations.attr -> 'country' as country
FROM pets,photos,locations
WHERE photos.pet_id = pets.id
AND photos.location_id = locations.id
GROUP BY pets.id,locations.attr -> 'country';

Which gives me:

Whereas I want:

Answer 1

Lose the pets.id from GROUP BY:

SELECT COUNT(DISTINCT pets.id),locations.attr -> 'country' as country
FROM pets,photos,locations
WHERE photos.pet_id = pets.id
AND photos.location_id = locations.id
GROUP BY locations.attr -> 'country';

EDIT:

You don't really need to join the pets table. Also, use explicit JOIN syntax:

select
    l.attr -> 'country' country,
    count(distinct p.pet_id)
from photos p
inner join locations l
on p.location_id = l.id
group by l.attr -> 'country';

Without using COUNT(DISTINCT):

select 
    country, count (pet_id)
from (
    select
        l.attr -> 'country' country,
        p.pet_id
    from photos p
    inner join locations l
    on p.location_id = l.id
    group by l.attr -> 'country', p.pet_id
) t
group by country;

http://rextester.com/YVR16306