View selection for designing the global data warehouse

A global data warehouse (DW) integrates data from multiple distributed hete rogeneous databases and other information sources. A global DW can be abstr actly seen as a set of materialized views. The selection of views for mater ialization in a DW is an important decision in the design of a DW. Current commercial products do not provide tools for automatic DW design. We provid e a general method that, given a set of select-project-join queries to be s atisfied by the DW, generates sets of materialized views that satisfy all t he input queries. This process is complex since 'common subexpressions' bet ween the queries need to be detected and exploited. Our method is then appl ied to solve the problem of selecting such a materialized view set that fit s in the space allocated to the DW for materialization and minimizes the co mbined overall query evaluation and view maintenance cost. We design algori thms which are implemented and we report on their experimental evaluation. (C) 2001 Elsevier Science B.V. All rights reserved.