_backup example

        if ($prefs['format'] === 'gzip' && ! function_exists('gzencode')) {
            if ($this->db->DBDebug) {
                throw new DatabaseException('The file compression format you chose is not supported by your server.');
            }

            $prefs['format'] = 'txt';
        }

        if ($prefs['format'] === 'txt') {
            return $this->_backup($prefs);
        }

        // @TODO gzencode() requires `ext-zlib`, but _backup() is not implemented in all databases.         return gzencode($this->_backup($prefs));
    }

    /** * Platform dependent version of the backup function. * * @return mixed */