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Abstract : |
In the data warehousing approach to the in-tegration of data from multiple information sources, selected information is extracted in advance and stored in a repository. A data warehouse (DW) can therefore be seen as a set of materialized views defined over the sources. When a query is posed, it is evaluated locally, using the materialized views, without access-ing the original information sources. The ap-plications using DWs require high query per-formance. This requirement is in conflict with the need to maintain in the DW updated in-formation. The DW configuration problem is the problem of selecting a set of views to mate-rialize in the DW that answers all the queries of interest while minimizing the total query evaluation and view maintenance cost. In this paper we provide a theoretical frame-work for this problem in terms of the relational model. We develop a method for dealing with it by formulating it as a state space optimiza-tion problem and then solving it using an ex-haustive incremental algorithm as well as a *Research supported by the European Commission under, |
