prefetch_related with Prefetch with queryset with explicit Ordering Ignored

[Alex Rothberg]

Given these models:

class Parent(models.Model):
    pass

class Child(models.Model):
    saved_dt = models.DateTimeField(auto_now_add=True)
    parent = models.ForeignKey(Parent)

I am executing this query (for each Parent I want to get the child_set in sorted order):

[m.child_set.order_by('saved_dt') for m in Parent.objects.prefetch_related(Prefetch('child_set', Child.objects.order_by('saved_dt'))).all()]

I would expect that to be two SQL queries, but in reality I see N+2 where N is the number of Childs:

SELECT "prefetch_parent"."id" FROM "prefetch_parent"; args=()
SELECT "prefetch_child"."id", "prefetch_child"."saved_dt", "prefetch_child"."parent_id" FROM "prefetch_child" WHERE "prefetch_child"."parent_id" IN (1, 2) ORDER BY "prefetch_child"."saved_dt" ASC; args=(1, 2)
SELECT "prefetch_child"."id", "prefetch_child"."saved_dt", "prefetch_child"."parent_id" FROM "prefetch_child" WHERE "prefetch_child"."parent_id" = 1 ORDER BY "prefetch_child"."saved_dt" ASC LIMIT 21; args=(1,)
SELECT "prefetch_child"."id", "prefetch_child"."saved_dt", "prefetch_child"."parent_id" FROM "prefetch_child" WHERE "prefetch_child"."parent_id" = 2 ORDER BY "prefetch_child"."saved_dt" ASC LIMIT 21; args=(2,)