Extending TP-monitors for intra-transaction parallelism

Inter-transaction parallelism, the concurrent execution of independent client transactions, is currently well supported by database systems. Intra-transaction parallelism, the parallel execution of operations within the same transaction, is generally not supported, even though often necessary especially in non-standard applications. The authors show how database operations within the same transaction can be executed concurrently by executing them as independent sub-transactions. This is possible because they employ a two-level transaction approach where the lower level is provided by virtually any of today's databases. The higher level is realised by a transaction processing monitor that is extended with an additional transaction manager for the scheduling of application service calls. They present results of a prototype implementation using Tuxedo and a relational database system using a document management application as an example.