#31535: Calling annotate with a case statement that references a recursive many
to
many relationship creates duplicates.
-------------------------------------+-------------------------------------
Reporter: David Cooke | Owner: nobody
Type: Bug | Status: closed
Component: Database layer | Version: master
(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
-------------------------------------+-------------------------------------
Comment (by Simon Charette):
The ORM is able to optimize `.filter(unlocked_by__in=solved_challenges)`
into an `INNER JOIN` but it cannot do the same for annotations because it
could be doing some special handling of `NULL` and it would require some
pretty sophisticated introspection to determine it's safe to do. It would
also be backward incompatible at this point. You should rely on `Subquery`
or even `Exists` in your reported case instead.
--
Ticket URL: <https://code.djangoproject.com/ticket/31535#comment:3>
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