Transaction-Centric Reconciliation in Disconnected Client-Server Databases

As mobile computing devices become more and more common, mobile databases are becoming popular. An important feature of these database systems is their ability to allow optimistic replication of data by providing disconnected mobile devices the ability to perform local updates. The key problem to this approach is the reconciliation problem, i.e. the problem of serializing potentially conflicting updates from disconnected clients on all replicas of the database. Reconciliation of conflicting updates is especially critical for disconnected databases where disconnected updates are allowed. We examine some choices for providing solutions to the reconciliation problem. We then present an algorithm that combines multiversion concurrency control schemes on a server with reconciliation of updates from disconnected clients. We also describe a simple but illustrative sample application. Finally we present our conclusions.