Bookmark Subscriptions and Persisted Acknowledgments

A bookmark subscription typically also requests the persisted acknowledgment (the AMPS clients do this automatically). In this case, once the replay has reached the end of the transaction log, AMPS periodically returns an acknowledgment that includes the last bookmark written to the local transaction log and acknowledged by all replication destinations that are currently using sync acknowledgment.

This information helps with application recovery, particularly in cases where publishers are intermittent or low-volume, and the last message for a subscription is significantly older than the last message evaluated for delivery to the subscription.

This also helps to manage failover in situations where multiple instances in a given replication fabric are accepting publishes by providing a stable failover point across instances.