What is the difference between an Oracle materialized view and a regular view?
The main difference between Oracle materialized views and regular views is:
- Data storage methods: A view is a virtual table that does not store any data, it is just a logical definition of a query. On the other hand, a materialized view is an actual object storing data, which saves the query results on the disk when created. This allows subsequent query operations to directly retrieve data from the materialized view without needing to re-execute the query.
- Data updating method: Views do not allow direct data updating operations because they are simply used to display query results, updating views can affect the data in their base tables. On the other hand, materialized views can allow direct data updating as they are objects that actually store data.
- Data synchronization methods: The data in the view is obtained in real time from its base table, with the query being re-executed each time to obtain the latest results. On the other hand, materialized view data is refreshed periodically or automatically when there are changes in the base table data to keep it synchronized with the base table data.
- Performance of Queries: Materialized views store the results of queries, allowing data to be directly accessed from the materialized view during a query, avoiding redundant query operations and improving query performance. In contrast, regular views may have lower performance since they need to execute a query each time.
- 物化视图适合处理大型数据集，以提高查询性能；而视图适合简化复杂查询，提供更简洁的数据访问方式。
Overall, materialized views perform better than regular views in terms of performance. However, they require additional storage space and regular refreshing to keep data synchronized, so the cost of storage space and data synchronization should be taken into consideration when using them. Regular views are more suitable for simple queries and temporary data display needs.
