def remove_session(self, session):
        """
        :param sqlalchemy.session.Session session: Database session to remove
        """
        try:
            del session.redis
        except AttributeError:
            pass
        try:
            del session.index_new[self.cls_name]
            del session.index_dirty[self.cls_name]
            del session.index_deleted[self.cls_name]
        except (AttributeError, KeyError):
            log.warning('Removing a session that has no indexing sets.')
        self.sessions.remove(session)