Integration of Time Versions into a Relational Database System

Abstract

New application areas for database systems, such as office automation and CAD/CAM will require to support not only access to the current data, as is done in current database systems, but also to previous instances of the data (versions). This means that time version support is needed. This paper presents the design considerations for a database system currently under implementation, that integrates time version support as a normal database function. It is shown that many subtle issues, such as choice of a suitable timestamp, how to store history data in a compact form, how to integrate version management into update processing, recovery, concurrency control, etc., have to be considered together to obtain an optimal design.