#33772: Queryset first() returns different result than queryset[0] when using
ExpressionWrapper
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Reporter: Pablo Pissi | Owner: nobody
Type: Uncategorized | Status: closed
Component: Database layer | Version: 3.2
(models, ORM) |
Severity: Normal | Resolution: invalid
Keywords: | Triage Stage:
ExpressionWrapper,first,queryset | 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):
* status: new => closed
* resolution: => invalid
Comment:
This is happening because you don't explicitly define an ordering for your
queryset so [https://www.percona.com/blog/2017/04/07/non-deterministic-
order-select-limit/ the database can return whatever rows it wants] in the
case of `[0]` while `.first()` explicitly order by `pk`
[https://github.com/django/django/blob/49b470b9187b6be60e573fed08c8f4a87f133750/django/db/models/query.py#L1035
if no ordering is specified].
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Ticket URL: <https://code.djangoproject.com/ticket/33772#comment:1>
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