Issue with media library on 3.4.x

I’m upgrading a site from 3.2.1 to 3.4.2 and I’m having an issue with my media library. The database upgrade finishes without issue but then most of my media library items go missing. I have confirmed that this is neither a plugin nor theme issue. This is present in the Media Library in the admin, not just my front-end theme.

I have been using the prefix “sp_” instead of “wp_” for my tables and noticed that in my old “sp_postmeta” table there are several meta_keys with value “_sp_attached_file”. If I change these to “_wp_attached_file”, all the items in the Media Library return!

Ok, so I guess in versions previous to 3.4, it was using my defined prefix on these meta_keys and now it’s using “_wp” for them. (I tried the 3.5RC2 to see if it was different and it wasn’t. I still had to change the values to “_wp_attached_file”.)

So I was able to fix it, but looking at the DB dump there are lots of places that use the prefix “_sp” and I’m wondering if they need to be “_wp” as well. Ultimately I’m just curious about the consistency here.