title: Django with cassandra backend - update_last_login method error
body: <p>I am trying to use cassandra as my DB. I moved the auth_user table to cassandra. I created a custom backend class and write my own implementation to the following methods:</p>
  
  <pre><code>def authenticate(...)
  def get_group_permissions()
  def has_perm()
  </code></pre>
  
  <p>and few more methods defined in the django docs.</p>
  
  <p>Now i am able to add new user and authentication works, but django tries to update the last login datetime field. Now it is throwing error as there is no record in sql database.</p>
  
  <p>If i comment out the following line in django/admin/auth/models.py file (line no. 31)</p>
  
  <pre><code>user.save(update_fields=['last_login'])
  </code></pre>
  
  <p>everything works properly. </p>
  
  <p>I need to know a simple way to override this update_last_login -> user.save method.
  I use django 1.5.2 version
  Thanks</p>
  
  <p><strong>Update:</strong>
  I got the solution by disconnecting the signal as follows in my custom BACKEND class:</p>
  
  <pre><code>from django.contrib.auth.models import update_last_login
  from django.contrib.auth.signals import user_logged_in
  ...
  user_logged_in.disconnect(update_last_login)
  </code></pre>