As described in this previous streamsdev post, one of the new features of Streams 3.2.2 Beta is the concept of consistent regions. Consistent regions provide resiliency to an SPL application by providing the ability to recover from failures. We name these regions consistent because the SPL runtime periodically establishes a consistent state for a given sub-graph (i.e., a region). The consistent state comprises of a collection of persisted operator states that are consistent with having processed all tuples up to a certain logical point. On a failure, a region is reset to its last successfully persisted state, and source/start operators of a region can replay any tuples submitted after the restored state. The replay enables applications to achieve at-least-once tuple processing.