Refresh Materialized View

Description

In a database, a materialized view is a special type of view that stores the query results in the form of a table within the database. When the data of the tables that the materialized view depends on changes (such as insert, overwrite, update, delete operations), the materialized view will automatically become invalid and cannot be used for queries and rewriting. To ensure that the data of the materialized view remains up-to-date, it is necessary to manually refresh the materialized view.

For more detailed information, please refer to Materialized View.

Syntax

REFRESH MATERIALIZED VIEW mv_name;

Parameter Description

• mv_name: Specifies the name of the materialized view to be refreshed.

Example

1. Suppose we have a materialized view my_mv, which is created based on the join query results of the employees table and the departments table. Now we need to refresh my_mv to ensure it contains the latest employee and department information. The following SQL statement can be used:

   REFRESH MATERIALIZED VIEW my_mv;
   

2. Another example, if we have a materialized view sales_summary, which generates a sales summary based on the sales data table (sales_data). When the sales data table changes, we need to refresh sales_summary to reflect the latest sales situation. The following SQL statement can be used:

   REFRESH MATERIALIZED VIEW sales_summary;
   

Notes

1. When performing the refresh materialized view operation, ensure that the table data on which the materialized view depends has been updated.
2. Refreshing a materialized view may consume a lot of system resources and time, especially when dealing with large amounts of data. Therefore, when performing this operation, ensure that the system load is low to avoid affecting other database operations.
3. Depending on the complexity and dependencies of the materialized view, the refresh operation may trigger a recalculation of the materialized view's query results. In some cases, consider using incremental refresh (if supported by the database system) to improve refresh efficiency.