Optimistic Global Transaction Management with Preserving the Global Integrity Constraints in MDBS

The objectives of multidatabase transaction management are to avoid the inconsistent retrievals and to preserve the global consistency in the presence of multidatabase updates. In order to maintain the global consistency, the MDBS must ensure the global integrity constraints as well as the global serializability of transactions. The global transaction manager must have the responsibility for global integrity constraints. It is impossible for LDBSs to preserve these global integrity constraints because neither local user nor the concurrency controller of each LDBS are aware of the integration process and the constraints. Hence, we need the global transaction manager that supports the global se-rializability and global integrity constraints. In this paper, we propose a multidatabase transaction model with preserving the global integrity constraint and local autonomy of LDBS. We also introduce optimistic concurrency control method based on our transaction model in order to ensure the global serializability.