A Performance Evaluation of Multi-Level Transaction Management*

Multi-level transactions are a variant of open nested transactions in which the subtransactions correspond to operations at different levels of a layered system ar-chitecture. The point of multi-level transactions is that the semantics of high-level operations can be ex-ploited in order to increase concurrency. As a conse-quence, undoing a transaction requires compensation of completed subtransactions. In addition, multi-level recovery methods have to take into account that high-level operations are not necessarily atomic if multiple pages are updated in a single subtransaction. This pa-per presents a performance evaluation of the multi-le-vel transaction management that is implemented in the database kernel system DASDBS. In particular, it is shown that multi-level recovery can be implemented in an efficient way. We discuss performance measure-ments, using a synthetic benchmark for processing complex objects in a multi-user environment. 1