Designing Inter-Class Concurrency Control Strategies for Real-time Database Systems with Mixed Transactions

Although many efficient concurrency control protocols have been proposed for real-time database systems, they are mainly designed for those systems with a single type of real-time transaction. Due to the very different performance requirements of each type of real-time transaction, these proposed protocols may not be suitable for mixed real-time database systems (MRTDBSs), where different types of real-time transactions, and even non-real-time transactions, may co-exist in the systems at the same time. In this paper, we propose strategies for resolving data conflicts between different types of transactions in a MRTDBS so that their different performance requirements can be achieved and, at the same time, the overall system performance can be improved. The performance of the proposed strategies is evaluated and compared with a real-time optimistic approach. The performance of our proposed conflict resolution methods has also been investigated in a more realistic environment with a limited number of priority levels and disk-resident data items.