Query processing can be speed up by keeping frequently accessed user's views materialized. however, the need to access base relations in response to queries can be avoided only if the materialized view iws adequately maintained. we propose a mthod in which all database updates to base relations are first filtered to remove from consideration those that can-not possibly affect the view. the conditions given for the detection of updates of this type, called irrelevant updates, are necessary and sufficient and are independent of the database state. for the remaining database updates, a differential algorithm can be applied to re-evaluate the view expression. the algorithm proposed exploits the knowledge provided by both the view definition expression and the database update operations.