mview_refresh_dop

Purpose

The mview_refresh_dop variable specifies the default DOP for refreshing materialized views.

Privileges

• Query variables

  • Global level

    Both the sys tenant and all user tenants can use the SHOW VARIABLES statement or the information_schema.GLOBAL_VARIABLES view (in MySQL mode) to view the values of global system variables.

  • Session level

    Both the sys tenant and all user tenants can use the SHOW VARIABLES statement or the information_schema.SESSION_VARIABLES view (in MySQL mode) to view the values of session system variables.

• Modify variables

  • Global level

    • The sys tenant can directly modify the values of global system variables.

    • MySQL-compatible tenants need the SUPER or ALTER SYSTEM privilege to modify the values of global system variables.

  • Session level

    The sys tenant and all user tenants can directly modify the values of session system variables in their respective tenants.

Attributes

Settings

1. Session level

   Set mview_refresh_dop within the current session to control the default refresh parallelism for materialized views in that session. Any manual refresh of materialized views initiated in this session will use this value if parallelism is not explicitly specified.

2. Global level

   Set the mview_refresh_dop globally to affect all sessions, including both manual and automatic refreshes of materialized views. Any refresh initiated across sessions will use this value if parallelism is not explicitly specified.

3. If you set the mview_refresh_dop variable to 0 or 1, parallel refreshes are disabled.

Examples

• Set the default refresh parallelism for the current session.

  obclient> SET mview_refresh_dop = 5;
  

• Set the global default refresh parallelism.

  obclient> SET GLOBAL mview_refresh_dop = 5;
  

References

• Refresh materialized views (MySQL mode)
• Refresh materialized views (Oracle mode)