I found the solution here but I tweak it a little more.
1. Download the Plugin
It is not in the official repository so I uploaded it here for you:
2. Upload the file
Place the file into your my-plugins folder.
3. Activate it
Yes, of course. Activate the plugin from your admin panel 😉
4. Edit config lines
Line 13, add folder or change the file location if needed:
$sitemap_file = $_SERVER['DOCUMENT_ROOT']."/sitemap.xml";
Code language: PHP (php)
Line 16, put your own domain:
$generator="http://EXAMPLE.com";
Code language: PHP (php)
Line 89, put your own domain again:
fwrite($handle, ' <loc>http://EXAMPLE.com</loc>');
Code language: HTML, XML (xml)
My Changes
I added:
1. Added a DESC to the MySQL query, better sorted by date (line 31).
2. Added the forum home page to the sitemap:
fwrite($handle, '<url>');
fwrite($handle, ' <loc>http://EXAMPLE.com/</loc>');
fwrite($handle, ' <lastmod>'.date("Y-m-d").'</lastmod>');
fwrite($handle, ' <changefreq>daily</changefreq>');
fwrite($handle, ' <priority>1.0</priority>');
fwrite($handle, '</url>');
Code language: PHP (php)
Extra
The plugin creates the Sitemap every time a new topic has been made. And also creates it when somebody updates (1 chance of 10, random).
I would like to test this plugin in a very busy site. Maybe you have to also configure the "random creation" when a new topic is created.
I will depend on the server resources I guess.
Feel free to post any comments or suggestions 😉