some properties of release of MusicBrainz are to be clarified

[candlecao]

For example:

1. What's the difference between "media_tracks_artist-credit_artist_id" and "release-group_artist-credit_artist_id"? The values of them in a row are mostly the same but not consistently.
   

2. What's the difference between "release-group_genres_id" and "genres_id"? They are not consistently the same.
   

Probably "release-group_genres_id" is genre of the release-group the release belongs to, which hence would be redundant.

3. "release-group_artist-credit_artist_id" may also be redundant.

[Yueqiao12Zhang]

As described in the header, they are the genre id corresponding media tracks and release group. If we reconcile them, we cannot distinguish them much. The only method should be linking them to their own subject.

[candlecao]

OK, this should be documented clearly.