#32711: MySQL performance regression in
forms.models.apply_limit_choices_to_to_formfield
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Reporter: Thomas Achtemichuk | Owner: nobody
Type: Uncategorized | Status: closed
Component: Forms | Version: 3.2
Severity: Normal | Resolution: worksforme
Keywords: | Triage Stage: 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 Mariusz Felisiak):
* cc: Adam Johnson (added)
* status: new => closed
* resolution: => worksforme
Comment:
Thanks for the report, however I cannot reproduce this issue on MySQL
8.0.23. All indexes are used correctly:
{{{
>>> User.objects.filter(Exists(User.objects.filter(Q(pk=OuterRef('pk')) &
Q(is_staff=True) & Q(groups__name='group_480')))).explain(analyze=True)
-> Nested loop inner join (cost=4.20 rows=4) (actual time=0.110..0.138
rows=2 loops=1)
-> Nested loop inner join (cost=2.80 rows=4) (actual
time=0.081..0.109 rows=4 loops=1)
-> Index lookup on U1 using
auth_user_groups_group_id_97559544_fk_auth_group_id (group_id='481')
(cost=1.40 rows=4) (actual time=0.058..0.065 rows=4 loops=1)
-> Single-row index lookup on auth_user using PRIMARY
(id=U1.user_id) (cost=0.28 rows=1) (actual time=0.009..0.010 rows=1
loops=4)
-> Filter: (0 <> U0.is_staff) (cost=0.27 rows=1) (actual
time=0.006..0.006 rows=0 loops=4)
-> Single-row index lookup on U0 using PRIMARY (id=U1.user_id)
(cost=0.27 rows=1) (actual time=0.004..0.005 rows=1 loops=4)
}}}
It looks that you don't have an index on `auth_user.id`, but I don't know
why.
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Ticket URL: <https://code.djangoproject.com/ticket/32711#comment:1>
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