#32658: Subquery ignores query ordering
-------------------------------------+-------------------------------------
Reporter: Bálint Balina | Owner: nobody
Type: Uncategorized | Status: closed
Component: Database layer | Version: 3.2
(models, ORM) |
Severity: Normal | Resolution: invalid
Keywords: Subquery, | Triage Stage:
annotations, ordering | Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Changes (by Simon Charette):
* cc: Simon Charette (added)
* status: new => closed
* resolution: => invalid
Comment:
IIRC the ordering is cleared for optimization purposes when `LIMIT`,
`DISTINCT` and aggregation are not used.
I think that ordering wouldn't be disabled if your function was properly
marked as being an aggregate (as it's one)
{{{#!python
children_query = MyModel.objects.filter(
parent=OuterRef('pk'),
).annotate(
child_names=Aggregate('name', function='group_concat'),
).values('child_names').order_by('name')
}}}
If you use `Func` instead of `Aggregate` then the ORM has to way to know
your opaque expression is performing aggregation and that ordering might
be relevant.
If using `Aggregate` instead of `Func` still results in cleared ordering
then please re-open this ticket as it shouldn't be the case otherwise this
a clearly a misuse of the ORM and likely only work in your case because
MySQL is very lax about `GROUP BY` requirements.
--
Ticket URL: <https://code.djangoproject.com/ticket/32658#comment:2>
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