We complete the actual data purge by deleting entire indices once all records have expired. For example, an index will rollover either when the average shard size breaches a threshold or when the age of the index exceeds the data retention period for the account/event type. We will wait until all documents in the index have expired, then delete the entire index.
Sometimes, the index doesn't rollover itself. In those cases, you can follow the instructions below to roll it over.