Views and queries: determinacy and rewriting

We investigate the question of whether a query can be answered using a set V of views. We first define the problem in information-theoretic terms: we say that V determines if V provides enough information to uniquely determine the answer to . Next, we look at the problem of rewriting in terms of V using a specific language. Given a view language and query language , we say that a rewriting language is complete for -to- rewritings if every can be rewritten in terms of V using a query in , whenever V determines . While query rewriting using views has been extensively investigated for some specific languages, the connection to the information-theoretic notion of determinacy, and the question of completeness of a rewriting language, have received little attention. In this paper we investigate systematically the notion of determinacy and its connection to rewriting. The results concern decidability of determinacy for various view and query languages, as well as the power required of compl...

• Type: Conference
• Year: 2005
• Where: PODS
• Authors: Luc Segoufin, Victor Vianu
• Keywords: Complete Rewriting Languages, Database, PODS 2005, Query Language, Query Languages