Schema-Based Independence Analysis for XML Updates

Query-update independence analysis is the problem of determining whether an update affects the results of a query. Query-update independence is useful for avoiding recomputation of materialized views and may have applications to access control and concurrency control. This paper develops static analysis techniques for query-update independence problems involving core XQuery queries and updates with a snapshot semantics (based on the W3C XQuery Update Facility proposal). Our approach takes advantage of schema information, in contrast to previous work on this problem. We formalize our approach, sketch a proof of correctness, and report on the performance and accuracy of our implementation.