I don't know about active record but with Django it's simply: Post.objects.all().annotate(Count('comments')) Which produces (simplified, Django would actual

I don't know about active record but with Django it's simply: Post.objects.all().annotate(Count('comments')) Which produces (simplified, Django would actually explicitly select each column): SELECT posts.*, COUNT(comments.id) AS comments_count FROM posts LEFT OUTER JOIN comments ON (posts.id = comments.post_id) GROUP BY posts.id Nice, easy and without 1+N queries.