#26172: Don't query the database when filtering an already empty queryset ----------------------------------------------+--------------------------- Reporter: seddonym | Owner: nobody Type: Cleanup/optimization | Status: new Component: Database layer (models, ORM) | Version: 1.9 Severity: Normal | Keywords: orm, queryset Triage Stage: Unreviewed | Has patch: 0 Easy pickings: 0 | UI/UX: 0 ----------------------------------------------+--------------------------- If you have a queryset that has already been evaluated as empty, and you filter (or exclude) it, Django will hit the database again, even though the result will always be an empty queryset.
{{{ >>> queryset = MyModel.objects.filter(my_field='foo') >>> bool(queryset) # Hits the database - running bool will cache it False >>> queryset [] >>> queryset.filter(another_field='bar') # Hits the database [] >>> queryset.exclude(another_field='bar') # Hits the database [] }}} The ORM should check to see if the queryset is empty before running any further filters / excludes pointlessly. -- Ticket URL: <https://code.djangoproject.com/ticket/26172> 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/051.9247396551cc1f3abd9dbc2bcbc1afd2%40djangoproject.com. For more options, visit https://groups.google.com/d/optout.