Adaptive Commitment for Real-Time Distributed Transactions
Nandit R. Soparkar, Eliezer Levy, Henry F. Korth, Avi Silberschatz · 1992
Real-time distributed transaction management systems are useful for both real-time and high-performance database applications. Guaranteeing response times in such environments is dif-cult to achieve mainly due to the inherent asynchrony present. The standard approach to distributed transaction management is to employ the two-phase locking scheme in each of the participating sites, and to coordinate the executions of the various subtransactions through the use of the two-phase commit protocol. Such an approach ensures the atomicity and serial-izability properties of the transactions. Unfortunately, the unpredictability, the cost and the fault-tolerance properties of the two-phase commit protocol render it unsuitable for real-time applications. The approach taken in this paper is to identify ways in which a commit protocol can be made adaptive in the sense that under situations that demand it, such as a transient local overload, the system can dynamically change to a dierent commitment strategy. The decision to do so can be taken autonomously at any site. The dierent commitment strategies exploit a trade-o between the cost of commitment and the obtained degree of atomicity. The inexpensive