Path Dictionary: A New Approach to Query Processing in Object-Oriented Databases

We present a new access method, called the path dictionary index (PDI) method, for supporting nested queries on object-oriented databases. PDI supports object traversal and associative search, respectively, with a path dictionary and a set of attribute indexes built on top of the path dictionary. We discuss issues on indexing and query processing in object-oriented databases, describe the operations of the new mechanism, develop cost models for its storage overhead and query and update costs, and compare the new mechanism to the path index method. The result shows that the path dictionary index method is signiicantly better than the path index method over a wide range of parameters in terms of retrieval and update costs and that the storage overhead grows slowly with the number of indexed attributes.