Nested relations and object-orientation on secondary storage

This thesis discusses the implementation of inheritance and nesting in a relational database. The purpose of this is to integrate object-oriented concepts into the relational model.RELIX is a database progamming system based on the relational model. Inheritance and nesting are two important features which are desirable to have in a database. Therefore, our aim was to incorporate these features in RELIX. The implementation was done using RELIX's existing relational functionality, without any modification. Inheritance and nesting were implemented using the natural join, showing that they could be implemented using relational operations. New syntax was added to RELIX to enable the user to take advantage of inheritance and nesting, thus giving the programmer an object-oriented view on a relational database. We also took advantage of the dependence of inheritance and nesting on the natural join, and implemented an alternative algorithm for it based on the concept of a join index. This algorithm improves the performance of natural joins for low activity operations such as those associated with inheritance and nesting