A Unified Implementation of Concurrency Control and Recovery
Gustavo Alonso, Divyakant Agrawal, Amr El Abbadi · 1993
this paper, we discuss the characteristics of such a scheduler and develop efficient schedulers based on a new class of locks. We start by proposing an equivalent definition for PRED. The original definition of PRED was stated in a recursive manner, which hinders its use for the development of dynamic schedulers. Our definition is procedural, and provides us with an easy, graph testing protocol for recognizing all PRED executions. However, serialization graph testing is known to be inefficient, and since locking is widely used for concurrency control, we propose a locking based protocol to recognize a subclass of PRED. The unified theory relied on a specific implementation of the recovery mechanism, viz., logs and before images. We develop an alternative recovery mechanism, which also uses logs and before images, but allows more concurrency among transactions. This recovery mechanism is integrated with efficient locking based protocols.