Reduction of Update Propagation Overhead for Data Warehousing Incorporating OODBs

Since the requirement of data warehouse is increasing, it is necessary to develop eflcient mechanisms for data warehouses incorporating various kinds of database systems. Essentially, materialized views are used for data warehouses and various methods for relational databases have been developed. In this paper, we will first discuss a method to realize materialized views for object-on’ented databases (OODBS) using deputy objects. Since materialized views require to generate duplication of data, improvement of eficiency for update operations is important. We will handle this problem by the following two approaches: (1) reduction of duplicates by considering inheritance property, (2) speed-up update propagation by considering communication delay. Our approach allows objects to be updated at data warehouse sides. If a data object is updated, the eflect of update propagation in the same data warehouse must be completed as soon as possible. If update information is transmitted to the original OODB and the induced update operations are transmitted from the OODB to the data warehouse, the delay required for update completion will be large due to the communication delay between the data warehouse and the OODB systems. We will try to avoid communication delays for update propagation in the same data warehouse.