Supporting multiple view maintenance policies

Abstract

Materialized views and view maintenance are becoming increasingly important in practice. In order to satisfy different data currency and performance requirements, a number of view maintenance policies have been proposed. Immediate maintenance involves a potential refresh of the view after every update to the deriving tables. When staleness of views can be tolerated, a view may be refreshed periodically or (on-demand) when it is queried. The maintenance policies that are chosen for views have implications on the validity of the results of queries and affect the performance of queries and updates. In this paper, we investigate a number of issues related to supporting multiple views with different maintenance policies. We develop formal notions of consistency for views with different maintenance policies. We then introduce a model based on view groupings for view maintenance policy assignment, and provide algorithms, based on the viewgroup model, that allow consistency of views to be guaranteed. Next, we conduct a detailed study of the performance aspects of view maintenance policies based on an actual implementation of our model. The performance study investigates the trade-offs between different maintenance policy assignments. Our analysis of both the consistency and performance aspects of various view maintenance policies are important in making correct maintenance policy assignments.