Making Multiple Views Self-Maintainable in a Data Warehouse

A data warehouse collects and maintains a large amount of data from several distributed and heterogeneous data sources. Often the data is stored in the form of materialized views in order to provide fast access to the integrated data, regardless of the availability of the data sources. In this paper we focus on the following problem: for a given set of materialized select-project-join (SPJ) views, how can we ®nd and minimize the auxiliary data stored in a data warehouse in order to make all materialized views in the data warehouse self-maintainable? For this problem we ®rst devise an algorithm for ®nding such an auxiliary view set by exploiting information sharing among the auxiliary views and materialized views themselves to reduce the total size of auxiliary views. We then consider how to make the data warehouse still self-maintainable by minor modi®cations when there is a view addition to or deletion from it by giving an algorithm for this incremental maintenance purpose. Ó 1999 Elsevier Science B.V. All rights reserved.