A Data Warehouse (DW) can be used to integrate data from multiple distributed data sources. A DW can be seen as a set of materialized
views that determine its schema and its content in terms of the schema and the content of the data sources. DW applications
require high query performance. For this reason,t he design of a typical DW consists of selecting views to materialize that
are able to answer a set of input user queries. However,the cost of answering the queries has to be balanced against the cost
of maintaining the materialized views. In an evolving DW application,ne w queries need to be answered by the DW. An incremental
selection of materialized views uses the materialized views already in the DW to answer parts of the new queries,an d avoids
the re-implementation of the DW from scratch. This incremental design is complex and an exhaustive approach is not feasible.
We have developed a randomized approach for incrementally selecting a set of views that are able to answer a set of input
user queries locally while minimizing a combination of the query evaluation and view maintenance cost. In this process we
exploit “common sub-expressions” among new queries and between new queries and old views. Our approach is implemented and
we report on its experimental evaluation.