public function write($key, $vars)
    {
        $now = $this->db->now();

        $this->db->query("INSERT INTO {$this->table_name}"
            . " (`sess_id`, `vars`, `ip`, `changed`)"
            . " VALUES (?, ?, ?, $now)",
            $key, base64_encode($vars), (string)$this->ip);

        return true;
    }