Hi Eric.
This is the expected behavior (
https://docs.djangoproject.com/en/dev/ref/models/options/#ordering ).
If ordering is defined on model Meta, the ORDER BY SQL is included by
default in all query.
to avoid this behavior, you can use order_by() without parameters:
eg:
A.objects.order_by().values('b').annotate(most_recent=Max('created_at'))
On Wed, Jun 29, 2016 at 5:39 PM, eric conner <[email protected]> wrote:
> Hello!
>
> I'm using Django 1.9.7, MySQL innodb 5.7.11, and python 2.7.10.
>
> I noticed some strange behavior when running this query:
> q = A.objects.values('b').annotate(most_recent=Max('created_at'))
>
> Produces this SQL:
> SELECT `core_a`.`b_id`, MAX(`core_a`.`created_at`) AS `most_recent` FROM
> `core_a` GROUP BY `core_a`.`id` ORDER BY `core_a`.`id` ASC
>
> which groups by an unexpected field. I was expecting it to group by
> `core_a`.`b_id` rather than `core_a`.`id`.
>
> Here are my models:
> from __future__ import unicode_literals
>
> from django.db import models
> from django.utils import timezone
>
>
> class B(models.Model):
> created_at = models.DateTimeField(default=timezone.now)
>
>
> class A(models.Model):
> created_at = models.DateTimeField(default=timezone.now)
> b = models.ForeignKey(B)
>
> class Meta:
> ordering = ["id"]
>
>
> If I remove from model A these lines
> class Meta:
> ordering = ["id"]
> then the query produces SQL which groups by the b_id column as expected.
>
> Is this known behavior? Would this be considered a bug?
>
> Thanks,
> -Eric
>
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