gistfile1.py

from django.db import models

class Foo(models.Model):
    bar = models.PositiveSmallIntegerField(default=1)
    class Meta:
        ordering = ['bar']
        
class Child(Foo):
    barchild = models.PositiveSmallIntegerField(default=1)


>>> str(Child.objects.order_by('pk').query)
'SELECT "test_pk_foo"."id", "test_pk_foo"."bar", "test_pk_child"."foo_ptr_id", "test_pk_child"."barchild" FROM "test_pk_child" INNER JOIN "test_pk_foo" ON ("test_pk_child"."foo_ptr_id" = "test_pk_foo"."id") ORDER BY "test_pk_foo"."bar" ASC'

# order_by('pk') doesn't do anything, the default ordering is used instead! (Tested with
# sqlite3 and postgresql_psycopg2 engines)

>>> str(Child.objects.order_by('id').query)
'SELECT "test_pk_foo"."id", "test_pk_foo"."bar", "test_pk_child"."foo_ptr_id", "test_pk_child"."barchild" FROM "test_pk_child" INNER JOIN "test_pk_foo" ON ("test_pk_child"."foo_ptr_id" = "test_pk_foo"."id") ORDER BY "test_pk_child"."foo_ptr_id" ASC'

# order_by('id') works.

# Note that removing the default ordering in the parent Model also fixes the bug.