[Milhouse]

Because you seem like the right man to ask; does Textures13.db still get populated when XBMC is MySQL-based? My assumption was that MySQL negated the use of SQLite, but I thought I read somewhere here that texturecache.py keeps them in sync?

Yes, it still gets populated, switching to MySQL has no impact on Textures13.db

MySQL replaces the MyVideos75.db and MyMusic32.db files (the movie/tvshow and music media libraries, respectively) however Textures13.db remains as a local SQLite database on each and every client because it manages the local artwork cache that is unique to each client.

For every artwork image you have in your media library (whether it be MySQL or SQLite based), an optimised version - resized/re-sampled as appropriate, depending on client capabilities - is cached in the Thumbnails folder on the client and an entry for that cached file is added to Textures13.db.

Each time XBMC wants to display an image, if there is a row for the image in Textures13.db it will pull the cached file from the Thumbnails folder - if not, it will download the original file (which could be on the internet), create the cached image file in Textures13.db/Thumbnails, then use the cached file.

In either case, what does texturecache.py do with MySQL data?

The texturecache.py script accesses the XBMC media library data using JSON so it makes no difference to the script if XBMC is configured to use MySQL or SQLite.