Efficient Self-Maintenance of Materialized Views

Abstract

We address the problem of incrementally maintaining a materialized view using the view instance and the update but with only limited access to the base data. We give necessary and suffcient conditions for self-maintainability (handling updates without looking at all base data) for conjunctive-query (CQ) views. These conditions, which we call Complete Tests for Self-Maintainability or CTSM in short, are generated at view-definition time and are expressed as safe, nonrecursive Datalog queries. We show both a direct approach that yields surprisingly simple CTSM's for a class of CQ views with self-joins, when no knowledge of the base data is available, and a query-containment-based approach that can be systematically used to find CTSM's for more complex CQ views with or without additional knowledge about the base data.