An Algebraic Approach to Materialized Views Maintenance in Object Databases

View materialization is an important technique for data warehousing, high performance query processing, and OLAP. Materialized views (MVs) are derived from base extents that may not be local. Queries can be answered using MVs more quickly than using the base extents. However, MVs may be affected by updates to the base extents. MVs can either be re-computed or incrementally updated to reflect the updates to the base extents. Generally, re-computing the entire view is more expensive than propagating changes to the view incrementally. The cost of incremental view maintenance (IVM) can further be reduced if access to base extents can be avoided. We incrementally maintain MVs defined in the Object Query Language (OQL) proposed in the ODMG standard for object databases. For a certain class of OQL views and for some update operations we avoid access to base extents. This paper illustrates a solution to the IVM problem using an algebraic approach. We give examples of automatically generated incremental maintenance plans, and discuss performance issues that these raise.