IBM Israel Research Seminars

Many applications, such as e-commerce, routinely use copies of data that are not in sync with the database due to heuristic caching strategies used to enhance performance. We study concurrency control for a transactional model that allows update transactions to read out-of-date copies. Each read operation carries a freshness constraint that specifies how fresh a copy must be in order to be read. We offer a definition of correctness for this model and present algorithms to ensure several of the most interesting freshness constraints. We outline a serializability-theoretic correctness proof and present the results of a detailed performance study.

About the Speaker
Alan Fekete received the PhD degree in the mathematics department of Harvard University. He is an associate professor in the School of Information Technologies at the University of Sydney and has held visiting positions at Cornell, MIT and University of Washington. Most of his research lies in the application of methods from theoretical computer science to software systems. He is known for contributions to the theory of concurrency control for nested transaction systems, and for specification and verification of replication and process group management. His recent work includes ways to ensure consistency in service-oriented distributed systems and in transactional applications that use weak isolation mechanisms within the scope of a database management system. He also is active in the computer science education community. He is a Distinguished Scientist of the ACM.