| 摘要 |
Methods and systems for using algorithms in relational database management systems (RDBMSs) for incremental maintenance of materialized views with outerjoins are disclosed. The algorithms achieve the following goals with respect to a class of materialized outerjoin views and the performance of update operations: relax the requirement for the existence of the primary key attributes in a select list of the view to only some of the relations (i.e., the relations referenced as a preserved side in an outerjoin); relax null-intolerant property requirements for some predicates used in the view definition (i.e., predicates referencing relations which can be null-supplied by more than one outerjoin); and implement maintenance of outerjoin views by using one update statement (e.g., MERGE, UPDATE, INSERT, or DELETE) per view for each relation referenced in the view. The algorithms allow design and implementation of the incremental maintenance of materialized views with outerjoins to be integrated into an RDBMS. |
