Management of flexible transactions using semantics in multidatabase systems

We propose a multidatabase transaction management scheme using the flexible transaction model. In our approach, global subtransactions can be committed unilaterally at local sites before the global commit. Since such executions may not guarantee the traditional atomicity requirement of global transactions, a new correctness criterion is proposed. We also present a semantics-based concurrency control scheme and a commit protocol which ensure the proposed correctness criterion without requiring local DBMSs to provide prepare-to-commit operations