def db_type(self, connection):
        # The default implementation of this method looks at the
        # backend-specific DATA_TYPES dictionary, looking up the field by its
        # "internal type".
        #
        # A Field class can implement the get_internal_type() method to specify
        # which *preexisting* Django Field class it's most similar to -- i.e.,
        # an XMLField is represented by a TEXT column type, which is the same
        # as the TextField Django field type, which means XMLField's
        # get_internal_type() returns 'TextField'.
        #
        # But the limitation of the get_internal_type() / data_types approach
        # is that it cannot handle database column types that aren't already
        # mapped to one of the built-in Django field types. In this case, you
        # can implement db_type() instead of get_internal_type() to specify
        # exactly which wacky database column type you want to use.
        data = DictWrapper(self.__dict__, connection.ops.quote_name, "qn_")
        try:
            return connection.creation.data_types[self.get_internal_type()] % data
        except KeyError:
            return None
Calcuate the simple average over one hour, FULL_DURATION seconds ago.
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.2/django/db/models/fields/__init__.py/Field.db_type--crossover with--dataset/ETHPy150Open etsy/skyline/src/analyzer/algorithms.py/first_hour_average