| Summary: | 碩士 === 國立交通大學 === 資訊科學學系 === 82 === A new method for query optimization in object-oriented database
systems is proposed in this thesis. We propose a policy for
query optimizer to link two classe that have reference
hierarchy. We can link these two classes either by association
or inverse-association, dependent on the query predicate. By
this policy, the cost of query paln can be reduced. By viewing
the whole database schema as a graph, our method can extract
the query-related information to form a subgraph. In this
subgraph, the association order for optimizing the query is
decided by utilizing the new policy to link two classes. The
proposed method can be applied to any object-oriented database
systems. All the operations that object-oriented database
systems need are provided, including restriction, projection,
join, union, difference, and intersection. It can also optimize
a query that contains reference hierarchy and inheritance
hierarchy. These features can not be achieved by previously
proposed method. Finally, the implementation of our method is
presented to show it is feasible.
|
|---|
