Research issues in real-time database systems

Cataloged from PDF version of article.Today's real-time systems are characterized by managing large volumes of data. Efficient database management algorithms for accessing and manipulating data are required to satisfy timing constraints of supported applications. Real-time database systems involve a new research area investigating possible ways of applying database systems technology to real-time systems. Management of real-time information through a database system requires the integration of concepts from both real-time systems and database systems. Some new criteria need to be developed to involve timing constraints of real-time applications in many database systems design issues, such as transaction/query processing, data buffering, CPU, and IO scheduling. In this paper, a basic understanding of the issues in real-time database systems is provided and the research efforts in this area are introduced. Different approaches to various problems of real-time database systems are briefly described, and possible future research directions are discussed

A Comprehensive Concurrency Control Technique for Real-Time Database System

Real-time database must maintain the Temporal Consistency of the data which cannot be achieved with the conventional concurrency control techniques as they focus only on the consistency of the data. Different protocols exhibit good performance on different situations. But a single technique is inadequate to meet the demand of real-time database. To improve the concurrency control technique for real-time transactions, this paper will present a comprehensive technique that coordinates multi-version, OCC Sacrifice, Speculative Concurrency Control and 2PL-HP protocols. The presented technique uses best suited protocol based on the contention of transactions. Thus it can significantly improve the concurrency of transactions as well as increase the number of transactions

Virtual time synchronization in distributed database systems

Distributed systems synchronized by Virtual Time have been topics of recent interest. Virtual Time follows an optimistic philosophy relying on rollback for synchronization instead of abortion or blocKing Although many applications have been suggested as candidates for Virtual Time, few were simulated or implemented. This research reports on the first implementation and results of a Distributed Database Management System synchronized by virtual time. We argue that virtual time is a viable alternate concurrency control method for distributed database systems if its memory overhead can be absorbed

Optimistic replication

Data replication is a key technology in distributed data sharing systems, enabling higher availability and performance. This paper surveys optimistic replication algorithms that allow replica contents to diverge in the short term, in order to support concurrent work practices and to tolerate failures in low-quality communication links. The importance of such techniques is increasing as collaboration through wide-area and mobile networks becomes popular. Optimistic replication techniques are different from traditional “pessimistic ” ones. Instead of synchronous replica coordination, an optimistic algorithm propagates changes in the background, discovers conflicts after they happen and reaches agreement on the final contents incrementally. We explore the solution space for optimistic replication algorithms. This paper identifies key challenges facing optimistic replication systems — ordering operations, detecting and resolving conflicts, propagating changes efficiently, and bounding replica divergence — and provides a comprehensive survey of techniques developed for addressing these challenges