#11082: exclude subquery executed twice
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Reporter: handrews | Owner: nobody
Status: new | Milestone: 1.1
Component: Database layer (models, ORM) | Version: SVN
Resolution: | Keywords:
Stage: Accepted | Has_patch: 0
Needs_docs: 0 | Needs_tests: 0
Needs_better_patch: 0 |
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Comment (by clement):
Did a bit of digging, and it seems that this extra query is issued (gets
in django.db.connection.queries) when the Q object for the exclude clause
is inverted (then deepcopied). See
[http://code.djangoproject.com/browser/django/trunk/django/db/models/query.py#L482
django.db.models.query] and
[http://code.djangoproject.com/browser/django/trunk/django/db/models/query_utils.py#L151
django.db.models.query_utils].
Interestingly enough, as Q._combine uses also deepcopy, the same problem
exists when using a subquery in a Q object being a left hand operand on an
& or | operation. Example :
{{{
>>> pub_all = Publisher.objects.all()
>>> django.db.connection.queries
[]
>>> Book.objects.filter( Q(publisher__in=pub_all) & Q(name='aa') )
[]
>>> django.db.connection.queries
[{'time': '0.001', 'sql': u'SELECT `app_publisher`.`id`,
`app_publisher`.`name` FROM `app_publisher`'},
{'time': '0.001', 'sql': u'SELECT `app_book`.`id`, `app_book`.`name`,
`app_book`.`publisher_id` FROM
`app_book` WHERE (`app_book`.`publisher_id` IN
(SELECT U0.`id` FROM
`app_publisher` U0) OR `app_book`.`name` = aa
) LIMIT 21'}]
}}}
--
Ticket URL: <http://code.djangoproject.com/ticket/11082#comment:3>
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