id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
15844	Filtering by related objects causes unnecessary extra db hits when using model inheritance	Johannes Dollinger	nobody	"The failing test below illustrates the issue.

{{{
#!python
from django.test import TestCase
from django.db import models

class A(models.Model): pass
class B(A): pass

class R(models.Model):
     b = models.ForeignKey(B, related_name=""r"")


class T(TestCase):
     def test(self):
        b = B.objects.create()
        r = R.objects.create(b=b)
        # Fails: produces 2 queries
        self.assertNumQueries(1, lambda: list(R.objects.filter(b=b)))
        # Fails: produces 2 queries
        self.assertNumQueries(1, lambda: list(b.r.all())


}}}

The extra queries seem to be generated by `RelatedField._pk_trace()`."	Bug	closed	Database layer (models, ORM)	dev	Normal	fixed			Accepted	1	0	0	0	0	0