Constraint Maintenance for Replicated Databases

Abstract

In this paper we investigate the issues of maintaining consistency in a distributed environment that allows data replication but does not require strict consistency between the replicated data items. Under such an environment, a different divergence constraint can be specified between the primary copy and a replications are considered. Moreover, we address different consistency requirements imposed by system: consistency maintained by either following explicit integrity constraints or executing transuctions serializably. Different alternatives on maintaining the reqired consistency are proposed, and the tradeoffs between them are also discussed. Finally, we point out some consistency constraint maintenance pitfalls which are usually easy to be neglected by the system administrator under a partial replication environment.