#30256: autocomplete_fields cause one or two extra queries for each field wth
foreign key or many to many relation
--------------------------------------+------------------------------------
Reporter: George Tantiras | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: contrib.admin | Version: master
Severity: Normal | Resolution:
Keywords: autocomplete | Triage Stage: Accepted
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 Carlton Gibson):
* keywords: => autocomplete
* version: 2.1 => master
* stage: Unreviewed => Accepted
Comment:
OK, this is a gnarly one but I'm going to Accept it as a possible
optimization.
The **extra** queries are generated when rendering the `optgroups` for the
widgets.
django-autocomplete-light (DAL) [https://github.com/yourlabs/django-
autocomplete-
light/blob/230c9a119d24ef969a39c4fbd28207714f26ca58/src/dal/widgets.py#L132
excludes unselected self.choices before determining the options to
render], i.e. it only initially renders the selected option.
Where the selected option is **just** the foreign key value that we
already selected for the admin this query can be eliminated.
{{{
SELECT "inl_child2"."id", "inl_child2"."key_id", "inl_child2"."boolean",
"inl_child2"."child_key_id"
FROM "inl_child2" INNER JOIN "inl_child3_child_keys" ON ("inl_child2"."id"
= "inl_child3_child_keys"."child2_id")
WHERE "inl_child3_child_keys"."child3_id" = 1
}}}
Looks to already cover in this case:
{{{
SELECT "inl_child2"."id", "inl_child2"."key_id", "inl_child2"."boolean",
"inl_child2"."child_key_id"
FROM "inl_child2"
WHERE "inl_child2"."id" IN (2)
}}}
(Since the FK points to child2.id = 2 in this case.)
Forcing evaluation of the [https://github.com/yourlabs/django-
autocomplete-
light/blob/230c9a119d24ef969a39c4fbd28207714f26ca58/src/dal/widgets.py#L186
temporarily reduced queryset (here)] causes the query count to match that
observed in Django's own autocomplete, since we apply no such
optimization. (i.e All choices are required in `optgroups()` in Django's
version.)
Thus in theory there's a gain to be had here.
Thanks for the report George. Fancy working on a patch? 🙂
--
Ticket URL: <https://code.djangoproject.com/ticket/30256#comment:7>
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