Hong Dong Kweon

The Transactions of the Korea Information Processing Society (1994 ~ 2000), Vol. 5, No. 6, pp. 1377-1389, Jun. 1998
10.3745/KIPSTE.1998.5.6.1377,   PDF Download:

Abstract

Firm real-time transactions on firm real-time database systems are discarded when they miss their deadlines, as there is no value to completing them after they miss their deadlines. Several approaches that exploit the semantics of firm deadlines to improve the performance of firm real-time database systems have been proposed in the literature. They are based on locking or optimistic concurrency control. The performance comparisons of the two approaches differ with systems load. In this paper, we develop a novel policy termed stop/resume deferred restart policy, and a concurrency control algorithm based on the policy (termed Alternative Version Concurrency Control). When conflicts (due to priority) occur, our algorithm maintains the immediately restarted version as well as the stopped version of a transaction in order to use one of the two to meet the firm deadline. At last we show that our policy generates serializable schedules and show that our algorithm performs better than the traditionally used method for wide ranges of the system load for firm deadline transaction.

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