This script will empty the forums of all usenet posts, users and clean up the index tables. It will empty all posts in a usenet forum regardless of who posted it.

Make sure you have a working backup before running this for the first time!

What it does:

1. Deletes all usenet threads from thread table for all usenet forums specified in usenet_group.
2. Sets the replycount, lastpost details to null for all usenet forums.
3. Delete all posts that belonged to the threads we just deleted.
4. Deletes all searchindex entries for posts that we just deleted.
5. Resets the lastmsg numbers to zero in the usenet_group table.
6. Empties the usenet_article and usenet_ref tables
7. Deletes all users with a usertitle of 'Usenet Poster'
8. Deletes userfield table entries for the users we just deleted