#28477: Strip unused annotations from count queries
-------------------------------------+-------------------------------------
Reporter: Tom Forbes | Owner: Tom
Type: | Forbes
Cleanup/optimization | Status: assigned
Component: Database layer | Version: master
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 1
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by Reupen Shah):
Just a note to say that the behaviour I was describing was rectified in
https://github.com/django/django/pull/11062.
The third case from above now executes the following SQL query:
{{{
SELECT COUNT(*) FROM (
SELECT CONCAT("people_person"."first_name", CONCAT(' ',
"people_person"."last_name")) AS "full_name" FROM "people_person"
) subquery
}}}
Although the original ticket was about eliminating unneeded annotations
completely, the result above is good enough for me, as the group by has
been eliminated which was the real performance killer.
--
Ticket URL: <https://code.djangoproject.com/ticket/28477#comment:11>
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