Atomic commitment for integrated database systems

A systematic discussion of atomic commitment for heterogeneous database systems is presented. An analysis is given of two alternative protocols for atomic commitment: commitment of local transaction after or before the global commit or abort decision is made. The impact of the protocols on recovery and concurrency control is shown. Atomicity, consistency, isolation, and durability properties are achieved for global transactions. It is demonstrated that commitment before fits best to multilevel transactions. In this case, the commitment protocol causes no additional overhead and a higher degree of concurrency can be achieved