#26318: Unexpected / duplicated queries on nested Prefetch queryset with
repeated
model
-------------------------------------+-------------------------------------
Reporter: aleontiev | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: master
(models, ORM) |
Severity: Normal | Resolution:
Keywords: queryset | Triage Stage: Accepted
prefetch_related duplicate |
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by melinath):
I just ran into this as well, but without recursion. i.e. (with apologies
for the implied structure)
{{{
users = User.objects.prefetch_related(
Prefetch(
'person',
queryset=Person.objects.prefetch_related(
'books',
),
),
)
}}}
would generate 4 queries instead of three (because the books are
duplicated).
To be clear, this is a trimmed down version of the actual query I'm trying
to construct. I haven't tested it (and I don't know whether I'll be able
to any time soon.) Someone should try tweaking the test case to not use
recursion, is all I'm saying.
--
Ticket URL: <https://code.djangoproject.com/ticket/26318#comment:2>
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