I was just using that link as an example 
Unfortunately we cannot use that code because the import takes ages to import 20 million posts and the bulk import simply doesn’t work. There are missing pieces.
That’s why we had to write our own migration script. It does it all (pm, users, usergroups, categories, topic, replies) in about 6 hours with a 4 cores, 8gb ram but we noticed that we were missing the permalinks