Abstract: Maintenance of materialized view for query optimization in a database. The architecture provides the first practical algorithms for incrementally maintaining views with multiple outer joins and aggregated outer-join views. Materialized views with any combination of inner joins, one-sided outer joins and full outer joins, plus an optional aggregation on top, can be processed by algorithm(s) that construct incremental maintenance expressions based on converting the view definition a join-disjunctive normal form and exploiting database constraints to reduce maintenance overhead. A system comprises a view creation component for creating a materialized view definition that includes outer-joins a conversion component for converting an outer-join view expression into a normal form, and a maintenance component for updating the stored materialized view result associated with the materialized view definition.