#32828: Wrong .count() for GROUP BY on ordered queryset
-------------------------------------+-------------------------------------
Reporter: Maxim Petrov | Owner: nobody
Type: Bug | Status: closed
Component: Database layer | Version: 3.2
(models, ORM) |
Severity: Normal | Resolution: invalid
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by Mariusz Felisiak):
* status: new => closed
* resolution: => invalid
Comment:
Thanks for this report, however these queries can return different results
(see also #30655).
`count()` calls `SELECT COUNT(*)` (as described in
[https://docs.djangoproject.com/en/stable/ref/models/querysets/#count
docs]) without taking ordering into account, so in your case it returns
the number of `Foo`'s names (this behavior is in Django since
7bc57a6d71dd4d00bb09cfa67be547591fd759ce).
It can be surprising that columns from `order_by()` calls are included in
the `GROUP BY` clauses, that's we it's
[https://docs.djangoproject.com/en/3.2/topics/db/aggregation/#interaction-
with-default-ordering-or-order-by documented].
To get the same results you can clear ordering or add `data` to the
`values()`:
{{{
Foo.objects.order_by("date").values("name").annotate(models.Count("name")).order_by()
Foo.objects.order_by("date").values("name",
"date").annotate(models.Count("name"))
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/32828#comment:1>
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