The changelog provides a sort of audit log for unique jobs. It adds an entry for each event that could prove useful for debugging.
The changelog is automatically cleaned up based on how many items are allowed.
The changelog that is introduced in version seven is mostly intended for debugging purposes. If something goes wrong with a specific worker it can be used to gather information about what script did what in regards to this digest.
SidekiqUniqueJobs.configure do |config| config.max_history = 10_000 end
… More information about how the changelog works and how to access it.