Monitoring and Managing the Scheduler

Job Log

You can view information about job runs, job state changes, and job failures in the job log. The job log is implemented as the following two data dictionary views:

• *_SCHEDULER_JOB_LOG

• *_SCHEDULER_JOB_RUN_DETAILS

You can control the amount of logging that the Scheduler performs on jobs at both the job class and individual job level. Normally, you control logging at the class level, as this offers you more control over logging for the jobs in the class.

See "Viewing the Job Log" for definitions of the various logging levels and for information about logging level precedence between jobs and their job class. By default, the logging level of job classes is LOGGING_RUNS, which causes all job runs to be logged.

You can set the logging_level attribute when you create the job class, or you can use the SET_ATTRIBUTE procedure to change the logging level at a later time. The following example sets the logging level of jobs in the myclass1 job class to LOGGING_FAILED_RUNS, which means that only failed runs are logged. Note that all job classes are in the SYS schema.

BEGIN
  DBMS_SCHEDULER.SET_ATTRIBUTE (
   'sys.myclass1', 'logging_level', DBMS_SCHEDULER.LOGGING_FAILED_RUNS);
END;
/

You must be granted the MANAGE SCHEDULER privilege to set the logging level of a job class.

Window Log

The Scheduler makes an entry in the window log each time that:

• You create or drop a window

• A window opens

• A window closes

• Windows overlap

• You enable or disable a window

There are no logging levels for window activity logging.

To see the contents of the window log, query the DBA_SCHEDULER_WINDOW_LOG view. The following statement shows sample output from this view:

SELECT log_id, to_char(log_date, 'DD-MON-YY HH24:MM:SS') timestamp,
   window_name, operation FROM DBA_SCHEDULER_WINDOW_LOG;

    LOG_ID TIMESTAMP            WINDOW_NAME       OPERATION
---------- -------------------- ----------------- --------
         4 10/01/2004 15:29:23  WEEKEND_WINDOW    CREATE
         5 10/01/2004 15:33:01  WEEKEND_WINDOW    UPDATE
        22 10/06/2004 22:02:48  WEEKNIGHT_WINDOW  OPEN
        25 10/07/2004 06:59:37  WEEKNIGHT_WINDOW  CLOSE
        26 10/07/2004 22:01:37  WEEKNIGHT_WINDOW  OPEN
        29 10/08/2004 06:59:51  WEEKNIGHT_WINDOW  CLOSE

The DBA_SCHEDULER_WINDOWS_DETAILS view provides information about every window that was active and is now closed (completed). The following statement shows sample output from that view:

SELECT LOG_ID, WINDOW_NAME, ACTUAL_START_DATE, ACTUAL_DURATION
  FROM DBA_SCHEDULER_WINDOW_DETAILS;

    LOG_ID WINDOW_NAME      ACTUAL_START_DATE                    ACTUAL_DURATION
---------- ---------------- ------------------------------------ ---------------
        25 WEEKNIGHT_WINDOW 06-OCT-04 10:02.48.832438 PM PST8PDT +000 01:02:32
        29 WEEKNIGHT_WINDOW 07-OCT-04 10.01.37.025704 PM PST8PDT +000 03:02:00

Notice that log IDs correspond in both of these views, and that in this case the rows in the DBA_SCHEDULER_WINDOWS_DETAILS view correspond to the CLOSE operations in the DBA_SCHEDULER_WINDOW_LOG view.

Purging Logs

To prevent job and window logs from growing indiscriminately, use the SET_SCHEDULER_ATTRIBUTE procedure to specify how much history (in days) to keep. Once per day, the Scheduler automatically purges all log entries that are older than the specified history period from both the job log and the window log. The default history period is 30 days. For example, to change the history period to 90 days, issue the following statement:

DBMS_SCHEDULER.SET_SCHEDULER_ATTRIBUTE('log_history','90');

Some job classes are more important than others. Because of this, you can override this global history setting by using a class-specific setting. For example, suppose that there are three job classes (class1, class2, and class3), and that you want to keep 10 days of history for the window log, class1, and class3, but 30 days for class2. To achieve this, issue the following statements:

DBMS_SCHEDULER.SET_SCHEDULER_ATTRIBUTE('log_history','10');
DBMS_SCHEDULER.SET_ATTRIBUTE('class2','log_history','30');

You can also set the class-specific history when creating the job class.

Note that log entries pertaining to steps of a chain run are not purged until the entries for the main chain job are purged.

Purging Logs Manually

The PURGE_LOG procedure enables you to manually purge logs. As an example, the following statement purges all entries from both the job and window logs:

DBMS_SCHEDULER.PURGE_LOG();

Another example is the following, which purges all entries from the jog log that are older than three days. The window log is not affected by this statement.

DBMS_SCHEDULER.PURGE_LOG(log_history => 3, which_log => 'JOB_LOG');

The following statement purges all window log entries older than 10 days and all job log entries older than 10 days that relate to job1 and to the jobs in class2:

DBMS_SCHEDULER.PURGE_LOG(log_history => 10, job_name => 'job1, sys.class2');