It's not the size of the database that determines how often you refresh the materialized views. Rather, it's the frequecy with which the data changes on the source database and how important it is to the business that that data is reflected in the target database in a timely fashion. We used 15 minutes for transaction oriented tables, 1 hour for tables that were less volatile and 24 hours for look-up tables (e.g., country_codes) where the table's content was only changed via a software change request. We used dbms_jobs to schedule and fire the refreshes. -- //www.freelists.org/webpage/oracle-l