99% of the time this is true. However, even when artist/abums/tracks are 100% matched the plex guids can change when doing a plex dance after a period of time. I’ve never fully understood why this happens but I suspect its something to do with back-end mapping between plex, musicbrainz and track release relationships.
For example, for reasons I’ll not get into here (you can read this [HowTo] Configure Popular Tracks Section to Prioritise Albums over every other release type! if your interest), I typically plex dance my entire music library once a year. Yes, the whole library…
I currently have 1,305 Artists with 10,174 albums, 150,396 tracks and over 45k music play history. ALL are tagged with musicbrainz picard and match 100% with plex. I ran a test a week or so back in prep for this yearly plex dance and approx 200 tracks changed their plex guids which had ratings and/or play history previously. I know this by querying the db.
SELECT * FROM metadata_item_settings WHERE metadata_item_settings.guid NOT IN (SELECT metadata_items.guid from metadata_items);
SELECT * FROM metadata_item_views WHERE metadata_item_views.guid NOT IN (SELECT metadata_items.guid from metadata_items);
This can mess up playlist etc… and I typically have to manually fix any I care about directly in the db.
Unmatched content when a plex dance is done has always changed the guid="local://xxxxxx" id for me which means you lose your ratings and if they are part of a playlist they’ll be removed, as the id link to it no longer exists.
