Research
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.
An Efficient Concurrency Control Technique for Mobile Database Environment
Day by day, wireless networking technology and mobile computing devices are becoming more popular for their mobility as well as great functionality. Now it is an extremely growing demand to process mobile transactions in mobile databases that allow mobile users to access and operate data anytime and anywhere, irrespective of their physical positions. Information is shared among multiple clients and can be modified by each client independently. However, for the assurance of timely access and correct results in concurrent mobile transactions, concurrency control techniques (CCT) happen to be very difficult. Due to the properties of Mobile databases e.g. inadequate bandwidth, small processing capability, unreliable communication, mobility etc. existing mobile database CCTs cannot employ effectively. With the client-server model, applying common classic pessimistic techniques of concurrency control (like 2PL) in mobile database leads to long duration Blocking and increasing waiting time of transactions. Because of high rate of aborting transactions, optimistic techniques aren`t appropriate in mobile database as well. This paper discusses the issues that need to be addressed when designing a CCT technique for Mobile databases, analyses the existing scheme of CCT and justify their performance limitations. A modified optimistic concurrency control scheme is proposed which is based on the number of data items cached, amount of execution time and current load of the database server. Experimental results show performance benefits, such as increase in average response time and decrease in waiting time of the transactions.
