Oracle maintains the data in materialized views by refreshing them after changes are
made to their master tables. The refresh method can be incremental (fast refresh) or
complete. For materialized views that use the fast refresh method, a materialized view
log or direct loader log keeps a record of changes to the master tables.

Materialized views can be refreshed either on demand or at regular time intervals.
Alternatively, materialized views in the same database as their master tables can be
refreshed whenever a transaction commits its changes to the master tables.

刷新物化视图
1. 物化视图刷新方式 : 增量(快速)刷新或者完全刷新
2. 快速刷新方式 : 使用物化视图日志或直接加载日志来记录主表数据的修改
3. 物化视图可以依据请求刷新,也可以按照定期的时间间隔刷新
4. 当物化视图与其对应的主表在同一个数据库时 , 那么物化视图可以在其主表的事务提交后同步刷新