查看文章

The main difficulty in enforcing global serializability in a multidatabase environment lies in resolving indirect transitive conflicts between multidatabase transactions. Indirect conflicts introduced by local transactions are difficult to resolve because the behavior or even the existence of local transactions is not known to the multidatabase system. To overcome these problems, we propose to incorporate additional data manipulation operations in the subtransactions of each multidatabase transaction. We show that if these operations create direct conflicts between subtransactions at each participating local database system, indirect conflicts can be resolved even if the multidatabase system is not aware of their existence. Based on this approach we introduce a multidatabase transaction management method that requires the local database systems to ensure only local serializability. The proposed method and its refinements do not violate the autonomy of the local database systems and guarantee global serializability by preventing multidatabase transactions from being serialized in different ways at the participating database systems.