Incremental refresh of materialized views for many-to-many relationships
Patent 6708179 Issued on March 16, 2004. Estimated Expiration Date: October 2, 2021. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
A framework for the incrementally refreshing a materialized view is provided. The materialized view is based on a query that references a projected table and another set of base tables. The query projects the columns of the projected table. To refresh the materialized view, a set of tuples is computed that identify rows to delete, insert, or otherwise modify in the materialized view in order to refresh it. The set of tuples is computed by computing a set of intersections, (1) one for the intersection between the query and the change log of the projected table, and (2) at least one other between the equijoin of the change log for one of the other base tables and the projected table. The query may define an equijoin between the projected table and at least one base table based on equijoin conditions that define a many-to-many relationship or a one-to-many relationship.