Concurrency Control and Deadlock Recovery of Active Rules

In rule-based active database systems, triggered rules are generally executed in the context of database transactions. Coupling mode, specified in rule definition, determines when a rule transaction will be launched and how these parallel rule transactions are to be serialized. Following an investigation on lock inheritance and lock preemption among these concurrent transactions when accessing shared data objects, this paper proposes an concurrency control algorithm, and based on transaction tree (forest), an effective deadlock detection algorithm and a minimal-price based deadlock recovery algorithm are presented.