US Patent 8694647 Read-only operations processing in a paxos replication system

Embodiments are directed to processing read-only operations without storing the operations persistently, determining a processing order for read-only requests, and to directing read-only requests to nodes best able to handle the requests. In an embodiment, a quorum leader receives various read-only requests. The quorum leader controls process ordering for replicas in the leader's quorum. The quorum leader determines an appropriate order for processing the read-only operations, without clock-based synchronization. The quorum leader sends the read-only request to an appropriate replica in the quorum and executes the read-only request at the appropriate replica without storing the operation persistently.