Update namespace statistics for the period identified by
        offset

def add_namespace_statistics(self, namespace, offset, data_points,
                                 byte_count):
        """Update namespace statistics for the period identified by
        offset"""
        self.cursor.execute(
            'INSERT INTO gauged_statistics VALUES (%s,%s,%s,%s) ON DUPLICATE '
            'KEY UPDATE data_points = data_points + VALUES(data_points),'
            'byte_count = byte_count + VALUES(byte_count)',
            (namespace, offset, data_points, byte_count))