Optimistic Concurrency Control for Maintaining the Global Integrity Constraint in MDBSs

The multidatabase system(MDBS) has a global database, a set of global and local transactions, and a global transaction manager(GTM) which is built on top of a number of pre-existing database management systems(DBMS) that are being integrated into a single MDBS. The global transaction manager has the responsibility for maintaining the global consistency of MDBS. It is impossible for LDBSs to preserve these global integrity constraints because neither the local user nor the transaction manager of each LDBS is aware of the integration process and these integrity constraints. Locally consistent transactions may generate global inconsistencies with the existence of global integrity constraints. Furthermore, the global serializability may be violated, even though each the local schedule is serializable. Hence, we need the global transaction management method that ensure the global serializability and logical consistency, together. In this paper, we investigate the transaction model for maintaining the global integrity constraints and propose the optimistic concurrency control method to guarantee the global serializability and logical consistency based on our transaction model.