Minimizing View Sets without Losing Query-Answering Power

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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 {\em not} a good basis for deciding whether or not a view should be selected. Instead, we should minimize the view set without losing its {\em query-answering power.} To formalize this notion, we first introduce the concept of ``p-containment.'' That is, a view set $\V$ is {\em 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 {\em 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.

Available Versions of this Item

• Minimizing View Sets without Losing Query-Answering Power (Extended version): Efficient view materialization in data integration and warehousing. (deposited 04 Oct 2000 17:00)
  • Minimizing View Sets without Losing Query-Answering Power. (deposited 08 Oct 2000 17:00) [Currently Displayed]