#28477: Strip unused annotations from count queries
-------------------------------------+-------------------------------------
Reporter: Tom | Owner: nobody
Type: | Status: new
Cleanup/optimization |
Component: Database | Version: master
layer (models, ORM) |
Severity: Normal | Keywords:
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-------------------------------------+-------------------------------------
The query below produces a SQL statement that includes the
Count('chapters'), despite not not being used in any filter operations.
{{{
Book.objects.annotate(Count('chapters')).count()
}}}
It produces the same results as:
{{{
Book.objects.count()
}}}
Django could be more intelligent about what annotations to include in the
query produced by `queryset.count()`, stripping out any annotations that
are not referenced by filters, other annotations or ordering. This should
speed up calls to count() with complex annotations.
There seems to be precedent for this: select_related calls are ignored
with count() queries.
--
Ticket URL: <https://code.djangoproject.com/ticket/28477>
Django <https://code.djangoproject.com/>
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