Allot of DJs often have unorganised music libraries and those that do, may have used Picard to tag music using info from musicbrainz. It would be very useful if rekordbox could work with accousticbrainz https://acousticbrainz.org/.
If music tracks have basic data, then rekordbox can fetch track info and other metadata from musicbrainz, by scanning the accousticID of tracks.
If tracks have already been tagged with musicbrainz info using Picard, then recordbox can fetch bpm and key info from the metadata of the track file and from accousticbrainz. If there is no bpm and key info for tracks in accousticbrainz, then rekordbox can submit to the database.