ok, so do the following
1. If you have WP mass delete already installed then deactivate and delete
2. the go to
WP Mass delete bbpress version
and download the plugin to your PC
Then go into Dashboard>plugins>add new and upload plugin
then upload the file you downloaded, and then activate
To execute go into Dashboard>settings>WP mass Delete, and choose the options with care !!!
I would suggest you tick Bypass trash, as otherwise you’ll only get them in there instead !!
The plugin works by using a sql command to make an array of post ID’s needing deleting, and then using wp_delete_post command to do each one in turn, which will pick up post meta and revisions as well, and cycling through the array.
Given you have 50,000 it may well error as well, so I’d suggest you start by limiting the period to a) check that it is working !
b) give it something that it might succeed at.
Once you know it works, you can try a full dump, but it may fall over.
If it does, then limiting to a period should let you delete a good size chunk each time, so hopefully in a couple of dozen iterations you should be able to get there.
Please come back and let me know how you get on – I can play with it a bit more if needed
