A token-based synchronization scheme for distributed real-time databases

摘要

Schedulers for real-time replicated database systems must satisfy two major requirements: transactions should meet their timing constraints, and mutual consistency of replicated data should be preserved. In this paper, we present a synchronization scheme, prove its correctness, and evaluate its performance in a distributed real-time database system. The algorithm adopts a token-based scheme for replication control and attempts to balance the urgency of real-time transactions with the conflict resolution policies. In addition, the algorithm employs epsilon-serializability (ESR), a new correctness criterion which is less stringent than conventional one-copy-serializability. The algorithm is flexible and very practical, since no prior knowledge of the data requirements or the execution time of each transaction is required.