#26172: Don't query the database when filtering an already empty queryset
-------------------------------------+-------------------------------------
Reporter: seddonym | Owner: nobody
Type: | Status: closed
Cleanup/optimization |
Component: Database layer | Version: 1.9
(models, ORM) |
Severity: Normal | Resolution: wontfix
Keywords: orm, queryset | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by akaariai):
* status: new => closed
* needs_better_patch: => 0
* resolution: => wontfix
* needs_tests: => 0
* needs_docs: => 0
Comment:
I don't see this as possible. The reason is that the ORM can't know if the
queryset will be empty when the filter() clause is applied. Consider:
{{{
Foo.objects.all().delete()
qs = Foo.objects.filter(pk__gte=0)
bool(qs)
Foo.objects.create(pk=1)
qs = qs.filter(pk=1) # There is a match even if
Foo.objects.filter(pk__gte=0) didn't match anything!
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/26172#comment:1>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
--
You received this message because you are subscribed to the Google Groups
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to django-updates+unsubscr...@googlegroups.com.
To post to this group, send email to django-updates@googlegroups.com.
To view this discussion on the web visit
https://groups.google.com/d/msgid/django-updates/066.1fc87cabcb7432775fd3ceff81bb6749%40djangoproject.com.
For more options, visit https://groups.google.com/d/optout.
