The Encyclopedia of Database Systems, a comprehensive work, provides easy access to relevant information on all aspects of very large databases. This volume features alphabetical organization of concepts covering main areas of very large databases. These 1000 entries offer convenient access to information in the field of databases with definitions and illustrations of basic terminology, concepts, methods, and algorithms, references to literature, and cross-references to other entries and journal articles. Topics for the encyclopedia were selected by a distinguished international advisory board, and written by world class experts in the field. The Encyclopedia of Database Systems is designed to meet the needs of research scientists, professors and advanced-level students in computer science and engineering. This encyclopedia is also suitable for practitioners in industry.