Sitecore stores its events in a database table called `EventQueue`. It is used for centralized event-based communication between Sitecore instances.

Sometimes this table grows quite large and it needs to be cleared of old events. Of course, there's a `CleanupEventQueue` task in Sitecore that you can schedule to run periodically. But sometimes one may need to clean that table manually.

My question is, when is it safe to remove an `EventQueue` record from the table? Or in other words, how can I know that a remote event has been fully processed by all instances?