on extending the functions of a relational database system
Relational database systems are attracting great interest from potential users outside the traditional areas in which such systems have been employed. Features of modern relational systems such as powerful query facilities, data and device independence, concurrency control, and recovery are useful in applications such as engineering design, office automation, and graphics. However, such applications place demands on the system that it must be extended to handle. This paper identifies three of these demands: storing non-coded information of arbitrary length within the database, dealing with aggregate objects as a unit, and improving support for interactive access. Additions to System R, a prototypical relational system, are introduced to satisfy these demands: long fields, for storing non-coded data, and complex objects, which declare the semantic relationships among data items and provide a means for adequately supporting interactive access.
relation relational database data database systems users feature query concurrency control recovery applications engine design automation graphics place paper informal aggregate object support interaction access semantic relationships device-independence