queryset.count() is less efficient than checking
queryset.exists(), so use
querySet.count() if you only want the count, and use
queryset.exists() if you only want to find out if at least one result exists.
queryset.count() performs an SQL operation that scans every row in the database table.
queryset.exists() simply reads a single record in the most optimized way (removing ordering, clearing any user-defined
This is especially relevant for Postgres because
count() can be very expensive.
So in practice, do this
def check_hounds(): queryset = HoundsModel.objects.all() if queryset.exists(): return "oh no. Run!"
Instead of this
def check_hounds(): queryset = HoundsModel.objects.all() if queryset.count() > 0: return "oh no. Run!"
Django Doctor will run this check by default. No configuration is needed but the check can be turned on/off using check code
count-instead-exists in your pyproject.toml file.