trying to convert an old wp multisite (v3.8) into a single site with data from active sites, since multisite setup is huge (containing about 50k subsites of which we only need about 2.5k) I can't just dump and import the data and then delete the data we don't need.
I've tried exporting the relevant data with wp-cli and then importing it to the new site, which resulted in 2 major problems:
- partial data for some users (a user may have created 80 posts but only 10 are imported).
- a mix-up with the attachments (import didn't change the attachment guid and the wrong pictures are displayed).
when importing the wxr file from wp-cli export all posts are imported correctly, but considering the number of files to be imported (over 5k wxr files) manual import through the wordpress admin panel isn't really an option.
any ideas or pointers?