Divergence control for epsilon-serializability

The authors present divergence control methods for epsilon-serializability (ESR) in centralized databases. ESR alleviates the strictness of serializability (SR) in transaction processing by allowing for limited inconsistency. The bounded inconsistency is automatically maintained by divergence control (DC) methods in a way similar to the manner in which SR is maintained by concurrency control mechanisms, but DC for ESR allows more concurrency. Concrete representative instances of divergence-control methods are described based on two-phase locking, timestamp ordering, and optimistic approaches. The applicability of ESR is demonstrated by presenting the designs of DC methods using other most known inconsistency specifications, such as absolute value, age, and total number of nonserializably read data items