-- MusicBrainz release-group id for an album (#5241). albums.mbid holds the
-- *release* id (Picard's musicbrainz_albumid: one edition), but Lidarr names
-- albums by release group, so re-acquisition and request completion need
-- this one. Not unique: several releases of one group can each be an album
-- row. Filled by the scanner from musicbrainz_releasegroupid, or by the
-- re-acquisition sweeper resolving the release through MusicBrainz.
ALTER TABLE albums ADD COLUMN release_group_mbid text;

CREATE INDEX albums_release_group_mbid_idx ON albums (release_group_mbid)
    WHERE release_group_mbid IS NOT NULL;