standby_db_preferred_upstream_log_region

Description

The standby_db_preferred_upstream_log_region parameter specifies the preferred region for log synchronization of a standby tenant.

Privilege requirements

• Query the parameter

  The sys tenant and all user tenants can query this parameter by using the SHOW PARAMETERS statement or the GV$OB_PARAMETERS view.

• Modify the parameter

  The sys tenant and user tenants can modify this parameter.

Attributes

Considerations

• After you specify the preferred region for log synchronization of a standby tenant by using the standby_db_preferred_upstream_log_region parameter, the standby tenant first synchronizes logs from a server in the specified region. To ensure high availability, if the standby tenant cannot obtain logs from all servers in the specified region, the system switches to another region based on a certain strategy to synchronize logs. The system then attempts to switch back to the specified region to continue log synchronization within a period of time.

• This parameter supports dynamic adjustment. When the standby tenant detects a change in the specified region for log synchronization, the system adjusts the priority in real time to switch servers.

Examples

• Set the preferred region for log synchronization of a standby tenant in the sys tenant of the cluster where the standby tenant resides.

  obclient> ALTER SYSTEM SET standby_db_preferred_upstream_log_region='BEIJING' tenant = 'restore_mysql_tenant';
  

• Set the preferred region for log synchronization of the current standby tenant.

  obclient> ALTER SYSTEM SET standby_db_preferred_upstream_log_region='BEIJING';