Which two statements are true with respect to the maintenance window? (Choose two.)
A.
A DBA can enable or disable an individual task in all maintenance windows.
B.
A DBA cannot change the duration of the maintenance window after it is created.
C.
In case of a long maintenance window, all Automated Maintenance Tasks are restarted
every four hours.
D.
A DBA can control the percentage of the resource allocated to the Automated
Maintenance Tasks in each window.
A and D are correct:
https://docs.oracle.com/cd/E11882_01/server.112/e25494/tasks.htm#ADMIN11836
A:
You can enable and disable individual maintenance tasks, and can configure when these tasks run and what resource allocations they are allotted.
B is incorrect:
The DBMS_SCHEDULER PL/SQL package includes a SET_ATTRIBUTE procedure for modifying the attributes of a window. For example, the following script changes the duration of the maintenance window SATURDAY_WINDOW to 4 hours:
BEGIN
dbms_scheduler.disable(
name => ‘SATURDAY_WINDOW’);
dbms_scheduler.set_attribute(
name => ‘SATURDAY_WINDOW’,
attribute => ‘DURATION’,
value => numtodsinterval(4, ‘hour’));
dbms_scheduler.enable(
name => ‘SATURDAY_WINDOW’);
END;
/
C is incorrect:
In the case of a very long maintenance window, all automated maintenance tasks except Automatic SQL Tuning Advisor are restarted every four hours. This feature ensures that maintenance tasks are run regularly, regardless of window size.
D:
To change the resource allocation for automated maintenance tasks within a maintenance window, you must change the percentage of resources allocated to the subplan ORA$AUTOTASK_SUB_PLAN in the resource plan for that window. (By default, the resource plan for each predefined maintenance window is DEFAULT_MAINTENANCE_PLAN.) You must also adjust the resource allocation for one or more other subplans or consumer groups in the window’s resource plan such that the resource allocation at the top level of the plan adds up to 100%.