To clean these threads and posts out I thought the best way was to create a "Temp" Node and run an sql update query on the Thread's table changing their NodeID to that of the Temp Node. Then simply through the XF UI delete the threads and then delete the Temp Node. By doing it this way, any attachments in the posts would also be deleted.
SQL I would run on the xf_thread table would be:
UPDATE xf_thread SET `node_id`= x WHERE `node_id`= y
y=NodeID of the Node that no longer exists
My question is...Is this the best way at the moment to clear out the orphaned threads and posts left over from the past...Would doing it this way get everything like attachments...Would anything be missed relating to those orphaned threads/posts?