Multidatabase performance evaluation

A model of a multidatabase transaction management system is presented, and the performance of two concurrency control algorithms operating in such an environment is analyzed. One algorithm does not impose any restrictions on either the structure of the concurrency control mechanisms used by local database management systems (DBMSs) or the type of multidatabase transactions. The other algorithm assumes that each local DBMS uses the two-phase locking protocol. The performance results presented demonstrate that in both cases the concurrent processing of global transactions provides a better throughput than their serial execution. However, the first algorithm may cause a significant number of global transaction rollbacks for some combinations of local and global transactions. For the second algorithm it is shown that the number of global transaction rollbacks is quite small for reasonable multiprogramming levels and that it performs almost as well as a distributed homogeneous database system