#23758: Going beyond 5 levels of subqueries causes AssertionError in bump_prefix
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Reporter: richardhowardsparx | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 1.7
(models, ORM) | Keywords: bump_prefix subquery
Severity: Normal | alias
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
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Regression from Django 1.6
The following code in the interactive shell will reproduce the issue:
{{{#!python
from django.contrib.auth.models import User
i = 0
x = User.objects.filter(pk=1)
while True:
x = User.objects.filter(pk__in=x)
i+=1
}}}
In django 1.7 it will throw the following AssertionError
{{{#!python
...
... in bump_prefix(self, outer_query)
829 while self.alias_prefix in self.subq_aliases:
830 self.alias_prefix = chr(ord(self.alias_prefix) + 1)
--> 831 assert self.alias_prefix < 'Z'
832 self.subq_aliases =
self.subq_aliases.union([self.alias_prefix])
833 outer_query.subq_aliases =
outer_query.subq_aliases.union(self.subq_aliases)
AssertionError:
}}}
while in django 1.6 it will loop infinitely.
I have tested this using multiple models in the loop, with the same
outcome.
--
Ticket URL: <https://code.djangoproject.com/ticket/23758>
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