Count of filter?

Question

Django

When executing a Model.objects.filter(...).count() query, how many queries will be made? Will it be SELECT COUNT FROM WHERE or will it first return all the objects in an array and count them in python? And purely for verification, how to display the contents of this query in sql form? As usual query doesn't exit, count returns int.

Answer 1

count() always makes a request, and only one. len() - doesn't always make a request. The SQL content of the count query can only be seen via connection:

from django.db import connection
print(connection.queries)

If you need to know the number of objects in the selection AND iterate over it - always use len(), it works like this:
If you only need to know the number - use count()

Answer 2

App for
debugging django-debug-toolbar.readthedocs.io/en/stable/pane...
When you need to look in one place - sometimes examples go to python2
stackoverflow.com/questions/971667/django-orm-how-...
The crux of the matter
https://docs.djangoproject.com/en/1.10/ref/models/...