Concurrency Control and Recovery in Transactional Process Management

Abstract

The unified theory of concurrency control and recovery integrates atomicity and isolation within a common framework, thereby avoiding many of the shortcomings resulting from treating them as orthogonal problems. This theory can be applied to the traditional read/write model as well as to semantically rich operations. In this paper, we extend the unified theory by applying it to generalized process structures, i.e., arbitrary partially ordered sequences of transaction invocations. Using the extended unified theory, our goal is to provide a more flexible handling of concurrent processes while allowing as much parallelism as possible. Unlike in the original unified theory, we take into account that not all activities of a process might be compensatable and the fact that these process structures require transactional properties more general than in traditional ACID transactions. We provide a correctness criterion for transactional processes and identify the key points in which the more flexible structure of transactional processes implies differences from traditional transactions.