Time-critical database scheduling: a framework for integrating real-time scheduling and concurrency control

A framework is presented for analysis of time-critical scheduling algorithms. The main assumptions are analyzed behind real-time scheduling and concurrency control algorithms, and a unified approach is proposed. Two main classes of schedulers are identified according to the availability of information about resource requirements and execution times: conflict-resolving schedulers resolve conflicts at run-time, and hence can only produce a sequence of operations satisfying task priorities and resource constraints; and conflict-avoiding schedulers determine resource requirements and expected execution times through offline transaction-class preanalysis and produce a complete time-critical schedule satisfying both timing and resource constraints. For the latter case, the resolution of overload is essential. Examples are given to illustrate the framework and the main classes of scheduling algorithms