Efficient Management of Object-Oriented Queries with Late Binding

To support new application areas for database systems such as mechanical engineering applications or office automation applications a powerful data model is required that supports the modelling of complex data, e.g. the object-oriented model. The object-oriented model supports subtyping, inheritance, operator overloading and overriding. These are features to assist the programmer in managing the complexity of the data being modelled. Another desirable feature of a powerful data model is the ability to use inverted functions in the query language, i.e. for an arbitrary function call fn(x)=y, retrieve the arguments x for a given result y. Optimization of database queries is important in a large database system since query optimization can reduce the execution cost dramatically. The optimization considered here is a cost-based global optimization where all operations are assigned a cost and a way of a priori estimating the number of objects in the result. To utilize available indexes the optimizer has full access to all operations used by the query, i.e. its implementation. The object-oriented data modelling features lead to the requirement of having late bound functions in queries which require special query processing strategies to achieve good performance. This is so because late bound functions obstruct global optimization since the implementation of a late bound function cannot be accessed by the optimizer and available indexes remain hidden within the function body. In this thesis the area of query processing is described and an approach to the management of late bound functions is presented which allows optimization of invertible late bound functions where available indexes are utilized even though the function is late bound. This ability provides a system with support for the modelling of complex relations and efficient execution of queries over such complex relations.