Concurrency Control for Approximate Query Processing of Real-Time Database Systems

Abstract

Real-time database systems [2, 8] can have timing constraints in the form of deadlines for the processing of database transactions. It is not always possible for real-time database systems to meet deadlines. A network partition or a host failure can cause some needed data to become inaccessible. Similarly, database transactions in a real-time system can share data, and while con-currency control is needed to ensure data integrity, concurrency control can cause transactions to miss their deadlines. For many real-time systems, such as computer integrated manufacturing, air traffic control systems and reservoir operation control, producing an approximate answer to a database query by a deadline is more useful than waiting for an exact answer and missing the deadline. Approximate query processing [14, 16] satisfies the timing constraints of real-time databases by providing approximate answers, instead of missing deadlines.