Incremental Design of a Data Warehouse

  • Authors:

  • Dimitri Theodoratos;Timos Sellis

  • Affiliations:

  • Computer Science Division, Department of Electrical and Computer Engineering, National Technical University of Athens, Zographou 157 73, Athens, Greece. dth@dblab.ece.ntua.gr;Computer Science Division, Department of Electrical and Computer Engineering, National Technical University of Athens, Zographou 157 73, Athens, Greece. timos@dblab.ece.ntua.gr

  • Venue:
  • Journal of Intelligent Information Systems - Data warehousing and knowledge discovery
  • Year:
  • 2000

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Abstract

A data warehouse (DW) can be seen as a set of materialized views defined over remote base relations. When a query is posed, it is evaluated locally, using the materialized views, without accessing the original information sources. The DWs are dynamic entities that evolve continuously over time. As time passes, new queries need to be answered by them. Some of these queries can be answered using exclusively the materialized views. In general though new views need to be added to the DW.In this paper we investigate the problem of incrementally designing a DW when new queries need to be answered and possibly extra space is allocated for view materialization. Based on an AND/OR dag representation of multiple queries, we model the problem as a state space search problem. We design incremental algorithms for selecting a set of new views to additionally materialize in the DW that: (a) fits in the extra space, (b) allows a complete rewriting of the new queries over the materialized views, and (c) minimizes the combined new query evaluation and new view maintenance cost. Finally, we discuss methods for pruning the search space so that efficiency is improved.