Minimizing View Sets without Losing Query-Answering Power

  • Authors:

  • Chen Li;Mayank Bawa;Jeffrey D. Ullman

  • Affiliations:

  • -;-;-

  • Venue:
  • ICDT '01 Proceedings of the 8th International Conference on Database Theory
  • Year:
  • 2001

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Abstract

The problem of answering queries using views has been studied extensively due to its relevance in a wide variety of data-management applications. In these applications, we often need to select a subset of views to maintain due to limited resources. In this paper, we show that traditional query containment is not a good basis for deciding whether or not a view should be selected. Instead, we should minimize the view set without losing its query-answering power. To formalize this notion, we first introduce the concept of "p-containment." That is, a view set V is p-contained in another view set W, if W can answer all the queries that can be answered by V. We show that p-containment and the traditional query containment are not related. We then discuss how to minimize a view set while retaining its query-answering power. We develop the idea further by considering p-containment of two view sets with respect to a given set of queries, and consider their relationship in terms of maximally-contained rewritings of queries using the views.