MU global taxonomy can be disrupted when blog db tables are copied directly in
|Reported by:||donncha||Owned by:|
If you've used MU much you'll probably have noticed that term_ids increase whenever you edit a category or tag. There's actually a bug #12206 about it but I closed it earlier today. This is how we maintain global tags/categories in MU. Whenever one is changed you have to assume some other blog may have used it already so you have to give the changed tag/cat a new term_id.
That makes it easy to maintain the correct term_id for the same tag or category across blogs.
Well, that all goes out the window when you copy a blog into a wpmu site using phpmyadmin and not through the WP importer.
It's not normally much of a problem except if you want to do something with the global tags like use the sitewide tags plugin. The problem showed there with numeric categories instead of the correct category showing on the tags table.
I received a patch for fixing the plugin that checked the cat_ID before inserting the post into the tags blog. (props Nasim Mansurov) Upon investigation I discovered he had copied his first blog's db tables directly into his MU site.
MU really should handle that more gracefully. It should do a once off check of the categories and tags, comparing them against the data in the sitecategories table and adjust the term_ids in the local blog's taxonomy.