Efficient View Self-Maintenance

Abstract

We consider the problem of maintaining a materialized view without accessing the base relations. More specifically, we would like to find a maximal test that guarantees that a view is self-maintainable (abbrev SM) under a given update to the base relations, i.e., can be maintained using only the view definition, its contents and the update. We observe that SM evaluation can be separated into a view-definition-time portion where a maximal test is generated solely based on the view definition, and an update-time portion where the test can be effciently applied to the view and the update. We call such a maximal test a Complete Test for View Self-Maintainability (abbrev This paper reports on some interesting new results for conjunctive-query views under insertion updates: 1) the CTSM's are extremely simple queries that look for certain tuples in the view to be maintained; 2) these CTSM's can be generated at view definition time using a very simple algorithm based on the concept of Minimal Z-Partition; 3) view self-maintenance can also be expressed as simple update queries over the view itself.