An Admission Control Paradigm for Value-cognizant Real-Time Databases

We propose and evaluate an admission control paradigm for RTDBS, in which a transaction is submitted to the system as a pair of processes: a primary task and a compensating task. The execution requirements of the primary task are not known a priori, whereas those of the compensating task are known a priori. Upon the submission of a transaction , an Admission Control Mechanism is employed to decide whether to admit or reject that transaction. Once admitted , a transaction is guaranteed to nish executing before its deadline. A transaction is considered to have nished executing if exactly one of two things occur: Either its primary task is completed (successful commitment), or its compensating task is completed (safe termination). Committed transactions bring a proot to the system, whereas a terminated transaction brings no proot. The goal of the admission control and scheduling protocols (e.g. concurrency control, I/O scheduling, memory management) employed in the system is to maximize system proot. We describe a number of admission control strategies and contrast (through simulations) their relative performance.