Hello there, Lets say I have these two models (sorry about the spanish names!) ( Django 1.8.6 and MySQL backend )
class Especialidad(models.Model): nombre = models.CharField(max_length=250, blank=False, unique=True) class Usuario(AbstractBaseUser): permisosEspecialidad = models.ManyToManyField("Especialidad", blank=True) Let u be some Usuario instance, and the following query: u.permisosEspecialidad.all().values_list('pk',flat=True) The actual printed query is: SELECT `samiBackend_especialidad`.`id` FROM `samiBackend_especialidad` INNER JOIN `samiBackend_usuario_permisosEspecialidad` ON ( `samiBackend_especialidad`.`id` = `samiBackend_usuario_permisosEspecialidad`.`especialidad_id` ) WHERE `samiBackend_usuario_permisosEspecialidad`.`usuario_id` = 8 As my understanding, since I'm only selecting the id field which is already present in the intermediary table (and is also a FK), the actual join is redundant, as I have all the info I need in this case. So the query could work like this SELECT `samiBackend_usuario_permisosEspecialidad`.`especialidad_id` FROM `samiBackend_usuario_permisosEspecialidad` WHERE `samiBackend_usuario_permisosEspecialidad`.`usuario_id` = 8 I guess this works this way because this particular case might be hard to detect or won't be compatible with any additional query building, however, for ForeignKey relations, this optimization is already done (If you select the primary key from the selected model only, it wont add a join) What would be the complications to implement this? Would it worth the effort? -- You received this message because you are subscribed to the Google Groups "Django developers (Contributions to Django itself)" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-developers+unsubscr...@googlegroups.com. To post to this group, send email to django-developers@googlegroups.com. Visit this group at http://groups.google.com/group/django-developers. To view this discussion on the web visit https://groups.google.com/d/msgid/django-developers/d31fdc22-8105-4be3-8c99-bc01279c4e5c%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.