standby_db_preferred_upstream_log_region

Description

standby_db_preferred_upstream_log_region specifies the preferred region for log synchronization for a standby tenant in a physical standby database scenario.

Privilege requirements

• Query the parameter

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

• Modify the parameter

  The sys tenant and user tenants can modify this parameter.

Attributes

Considerations

• After you set the standby_db_preferred_upstream_log_region parameter to specify the preferred region for log synchronization for a standby tenant, the standby tenant will prefer to synchronize logs from machines in the specified region. To ensure high availability, if the standby tenant cannot obtain logs from all machines in the specified region, the system will switch to other regions according to a certain strategy to synchronize logs and attempt to switch back to the specified region within a period of time to continue synchronizing logs.

• This parameter supports dynamic adjustment. When the standby tenant detects that the specified region for log synchronization has changed, the system will adjust the priority in real time to complete the switch of machines.

Examples

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

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

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

  obclient> ALTER SYSTEM SET standby_db_preferred_upstream_log_region='BEIJING';