public function create_index($keyspace, $column_family, $column,
        $data_type=self::KEEP, $index_name=NULL, $index_type=IndexType::KEYS)
    {
        $this->_alter_column($keyspace, $column_family, $column,
            $data_type=$data_type, $index_type=$index_type, $index_name=$index_name);
    }