The Reduced Ceiling Protocol for Concurrency Control in Real-time Databases with Mixed Transactions

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Original languageEnglish
Pages (from-to)65-80
Journal / PublicationComputer Journal
Issue number1
Publication statusPublished - 2000


This paper proposes a real-time concurrency control protocol called the reduced ceiling protocol (RCP) for real-time database systems consisting of hard and soft real-time transactions. The schedulability of hard real-time transactions can be improved by bounding the blocking time from soft real-time transactions. Different concurrency control strategies are proposed to resolve data conflicts between different combinations of hard and soft real-time transactions, and the properties of the RCP schedules are shown. In the RCP, methodologies are proposed to reduce the number of aborts for soft real-time transactions due to data conflicts with hard real-time transactions. Simulation experiments have been performed to study the performance of the RCP as compared with the optimistic concurrency control with wait 50 (OCC wait-50) under different workloads of soft real-time transactions, various ratios of read/write operations and deadline constraints. It has been found that the RCP can not only guarantee the performance of hard real-time transactions but also reduce the number of deadlines missed by the soft real-time transactions under all situations.