Designing data warehouses

A Data Warehouse (DW) is a database that collects and stores data from mult iple remote and heterogeneous information sources. When a query is posed, i t is evaluated locally, without accessing the original information sources. In this paper we deal with the issue of designing a DW, in the context of the relational model, by selecting a set of views to materialize in the DW. First, we briefly present a theoretical framework for the DW design proble m, which concerns the selection of a set of views that (a) fit in the space allocated to the DW, (b) answer all the queries of interest, and (c) minim ize the total query evaluation and view maintenance cost. We then formalize the DW design problem as a state space search problem by taking into accou nt multiquery optimization over the maintenance queries (i.e., queries that compute changes to the materialized views) and the use of auxiliary views for reducing the view maintenance cost. Finally, incremental algorithms and heuristics for pruning the search space are presented. (C) 1999 Published by Elsevier Science B.V. All rights reserved.