- Automatic Optimizer Statistics Collection
Gathers stale or missing statistics for all schema objects. The task name is 'auto optimizer stats collection'. - Automatic Segment Advisor
Identifies segments that could be reorganized to save space. The task name is 'auto space advisor'. - Automatic SQL Tuning Advisor
Identifies and attempts to tune high load SQL. The task name is 'sql tuning advisor'.
These tasks run during maintenance windows scheduled to open over night. Configuration of the maintenance tasks, their schedules and resource usage is possible using Enterprise Manager or PL/SQL APIs.
The "Automated Maintenance Tasks" screen displays the maintenance window for each task (Server > Automated Maintenance Tasks (link under Scheduler section)). Click the "Configure" button to navigate to the configuration screens.
Basic Task Configuration
The "Automated Maintenance Tasks Configuration" screen is the stating point for all maintenance task configuration.
The "Global Status" switch allows you to turn enable or disable all automated tasks for all maintenance windows.
The DISABLE and ENABLE procedures of the DBMS_AUTO_TASK_ADMIN package achieve the same result if they are called with no parameters.
EXEC DBMS_AUTO_TASK_ADMIN.disable;
EXEC DBMS_AUTO_TASK_ADMIN.enable;
The "Task Settings" section allows you to enable or disable individual tasks from all maintenance windows.
This can be done using the DBMS_AUTO_TASK_ADMIN package by specifying the task name in the CLIENT_NAME parameter of the DISABLE and ENABLE procedures.
BEGIN
DBMS_AUTO_TASK_ADMIN.disable(
client_name => 'auto space advisor',
operation => NULL,
window_name => NULL);
END;/
BEGIN
DBMS_AUTO_TASK_ADMIN.enable(
client_name => 'auto space advisor',
operation => NULL, window_name => NULL);
END;
/
The "Maintenance Window Group Assignment" section provides the most granular level of control. It allows tasks to be removed or added to individual maintenance windows.
This can be done using the DBMS_AUTO_TASK_ADMIN package by specifying the CLIENT_NAME and WINDOW_NAME parameters of the DISABLE and ENABLE procedures.
BEGIN
DBMS_AUTO_TASK_ADMIN.disable(
client_name => 'auto optimizer stats collection',
operation => NULL,
window_name => 'MONDAY_WINDOW');
DBMS_AUTO_TASK_ADMIN.disable(
client_name => 'auto space advisor',
operation => NULL,
window_name => 'MONDAY_WINDOW');
DBMS_AUTO_TASK_ADMIN.disable(
client_name => 'sql tuning advisor',
operation => NULL,
window_name => 'MONDAY_WINDOW');
END;
/
Task Parameter Configuration
The "Task Settings" section of the "Automated Maintenance Tasks Configuration" screen includes two "Configure" buttons.
The "Configure" button next to the "Optimizer Statistics Gathering" task takes you to the "Global Statistics Gathering Options" screen.
With the exception of the history retention, these settings can all be altered with the SET_GLOBAL_PREFS procedure in the DBMS_STATS package.
EXEC DBMS_STATS.alter_stats_history_retention(90);
EXEC DBMS_STATS.set_global_prefs('estimate_percent', '5');
The "Configure" button next to the "Automatic SQL Tuning" task takes you to the "Automatic SQL Tuning Settings" screen.
These settings can all be altered with the SET_TUNING_TASK_PARAMETER procedure in the DBMS_SQLTUNE package.
BEGIN
DBMS_SQLTUNE.set_tuning_task_parameter
('SYS_AUTO_SQL_TUNING_TASK','LOCAL_TIME_LIMIT', 1200);
DBMS_SQLTUNE.set_tuning_task_parameter
('SYS_AUTO_SQL_TUNING_TASK','ACCEPT_SQL_PROFILES', 'FALSE');
DBMS_SQLTUNE.set_tuning_task_parameter
('SYS_AUTO_SQL_TUNING_TASK','MAX_SQL_PROFILES_PER_EXEC', 20);
DBMS_SQLTUNE.set_tuning_task_parameter
('SYS_AUTO_SQL_TUNING_TASK','MAX_AUTO_SQL_PROFILES', 10000);
END;
/
Maintenance Window Configuration
The maintenance windows are defined using the Oracle Scheduler. Oracle provide a separate active maintenance window for each day, with all windows collected into a window group called "MAINTENANCE_WINDOW_GROUP". Clicking the "Edit Window Group" button on the "Automated Maintenance Tasks Configuration" screen allows you to view and modify the window group.
The whole window group can be enabled or disabled using this screen, or using the ENABLE and DISABLE procedures in the DBMS_SCHEDULER package.
BEGIN
DBMS_SCHEDULER.disable(
name => 'SYS.MAINTENANCE_WINDOW_GROUP',
force => TRUE);
DBMS_SCHEDULER.enable(
name => 'SYS.MAINTENANCE_WINDOW_GROUP');
END;
/
Clicking on the window name on this screen, or in the "Automated Maintenance Tasks Configuration" screen, takes you to the "View Windows" screen, which gives you a summary of the window configuration.
Click the "Edit" button alter the window definition.
These configuration changes can be performed using the SET_ATTRIBUTE procedure of the DBMS_SCHEDULER package.
BEGIN
DBMS_SCHEDULER.disable(name => 'SYS.MONDAY_WINDOW', force => TRUE);
DBMS_SCHEDULER.set_attribute(
name => 'SYS.MONDAY_WINDOW',
attribute => 'DURATION',
value => numtodsinterval(180, 'minute'));
DBMS_SCHEDULER.enable(name=>'SYS.MONDAY_WINDOW');
END;
/
If you wish to create additional maintenance windows, make sure they are assigned to the "MAINTENANCE_WINDOW_GROUP" window group.
Resource Plan Configuration
The "Edit Window" screen includes "View Resource Plan" and "Create Resource Plan" buttons. These buttons take you to the resource manager maintenance screens. All maintenance windows are assigned to the "DEFAULT_MAINTENANCE_PLAN" resource plan by default.
If necessary, you can edit this plan, or create a new plan.
If you create a new resource plan, you need assign it to the relevant maintenance windows in the "Edit Window" screen, or using the DBMS_SCHEDULER package.
BEGIN
DBMS_SCHEDULER.disable(name => 'SYS.MONDAY_WINDOW', force => TRUE);
DBMS_SCHEDULER.set_attribute(
name => 'SYS.MONDAY_WINDOW',
attribute => 'RESOURCE_PLAN',
value => 'MY_NEW_PLAN');
DBMS_SCHEDULER.enable(name=>'SYS.MONDAY_WINDOW');
END;
/
Relevant Views
The following views display information related to the automated database maintenance tasks:
- DBA_AUTOTASK_CLIENT_JOB
- DBA_AUTOTASK_CLIENT
- DBA_AUTOTASK_JOB_HISTORY
- DBA_AUTOTASK_WINDOW_CLIENTS
- DBA_AUTOTASK_CLIENT_HISTORY
