Designing the Global Data Warehouse with SPJ Views

A global Data warehouse (DW) integrates data from multiple distributed heterogeneous databases and other information sources. A global DW can be abstractly seen as a set of materialized views. The selection of views for materialization in a DW is an important decision in the implementation of a DW. Current commercial products do not provide tools for automatic DW design. In this paper we provide a generic method that, given a set of SPJ-queries to be satisfied by the DW, generates all the `significant' sets of materialized views that satisfy all the input queries. This process is complex since `common subexpressions' between the queries need to be detected and exploited. Our method is then applied to solve the problem of selecting such a materialized view set that fits in the space allocated to the DW for materialization and minimizes the combined overall query evaluation and view maintenance cost. We design algorithms which are implemented and we report on their experim..

Experimental Evaluation of Data Warehouse Configuration Algorithms

A Data Warehouse (DW) can be seen as a set of materialized views defined over relations that are stored in remote heterogeneous database systems. When a query is posed to the DW, it is evaluated locally, using only the materialized views. The DW configuration problem is the problem of selecting an optimal set of views to materialize that answer a given set of queries. The objective is the minimization of the combination of the query evaluation and view maintenance costs. In this paper we report on the experimental evaluation of an exhaustive algorithm and we develop new greedy and heuristic algorithms that expand only a small fraction of the states produced by the exhaustive algorithm. The algorithms are described in terms of a state space search problem. Finally, we report on experimental results and discuss the observed behavior of the algorithms

Heuristic Algorithms for Designing a Data Warehouse with SPJ Views

A Data Warehouse (DW) can be abstractly seen as a set of materialized views defined over relations that are stored in distributed heterogeneous databases. The selection of views for materialization in a DW is thus an important decision problem. The objective is the minimization of the combination of the query evaluation and view maintenance costs. In this paper we expand on our previous work by proposing new heuristic algorithms for the DW design problem. These algorithms are described in terms of a state space search problem, and are guaranteed to deliver an optimal solution by expanding only a small fraction of the states produced by the (original) exhaustive algorithm