Steps to fix missing genre and tag data on MusicBrainz mirror servers

If you recently updated your mirror server to the 2022-05-16 schema change release, we’re sorry to say that a bug in our upgrade script caused aggregate genre and tag data (if you had imported any) to be deleted. If you need this data, it can be re-imported from a recent dump, and we’ve written a script to help automate that.

You can safely ignore this post if

To restore the genre and tag data, follow these steps:

  1. Ensure you’ve replicated up to the most recent replication packet available. If you’re not sure, run ./admin/replication/LoadReplicationChanges. If you’re up-to-date, it should log “Replication packet … is not available.”
  2. Run git checkout production && git pull origin production.
  3. Turn off any cron jobs that update the database, including for replication.
  4. Run ./admin/sql/updates/
  5. Restart any cron jobs that you disabled.

You can verify that this process worked by checking the number of tags in the database: echo 'SELECT count(*) FROM tag' | ./admin/psql READWRITE. It should be over 200,000.

Sorry for the inconvenience, and let us know if you encounter any further issues.

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