Django 1.8 - Created QuerySet includes columns not in values

I am trying to get a query displaying the average comment rate. The request looks pretty straightforward - although Django seems to automatically add an extra created_at field in the generated expression group. Is there a way to remove it from the article group? Is it because of the default order defined in the META class of the models?

GROUP BY "authentification_antenne". "name", "review". "created_at" instead of just GROUP BY "authentification_antenne". "name"

Review.objects.select_related(
'appartement__antenne').values('appartement__antenne__name').annotate(average_rating=Avg('rating')).query

SELECT 
"authentification_antenne"."name", AVG("review"."rating") AS "average_rating" FROM "review" 
LEFT OUTER JOIN "staffing_appartement" ON ( "review"."appartement_id" = "staffing_appartement"."numero_contrat" ) 
LEFT OUTER JOIN "authentification_antenne" ON ( "staffing_appartement"."antenne_id" = "authentification_antenne"."id" ) 
GROUP BY "authentification_antenne"."name", "review"."created_at" 
ORDER BY "review"."created_at" DESC

      

        
        
        
      

    

And models.py

 class Review(models.Model):
     guest = models.ForeignKey(Guest)
     comment = models.TextField()
     rating = models.IntegerField(null=True)
     created_at = models.DateTimeField()
     imported_at = models.DateTimeField(auto_now=True)
     appartement = models.ForeignKey('staffing.appartement', null=True)

     class Meta:
         ordering = ['-created_at']

      

        
        
        
      

    

Edit - I confirm that the generated statement is correct when the created_at order is removed from the models.

Edit 2 - I solved it by adding my values ​​to the order_by clause to remove the default filtering

AirbnbReview.objects.select_related('appartement__antenne').values('appartement__antenne__name').order_by('appartement__antenne__name').annotate(average_rating=Avg('rating'))

      

        
        
        
      

    

thank