Oracle Tips by Burleson

SCHTASKS.EXE

C:\>SCHTASKS
INFO: There are no scheduled tasks present in the system.

C:\>

Since some of the external schedulers available on the most common operating systems have been presented, the following section will focus on the internal schedulers provided by the Oracle database.

Internal Oracle Job Scheduling

The Oracle scheduler allows jobs to be scheduled to run at a later date, or on a repeating cycle.  Information about the scheduling session’s environment is stored along with the scheduled job, allowing jobs to run in a consistent environment each time.  Scheduled jobs are placed on a job queue that is managed by a coordinator process, which periodically scans the job queue looking for jobs to execute.  When necessary, the coordinator process spawns job slaves to execute the jobs.  The basic architecture of the Oracle scheduler is shown in Figure 1.10.

Figure 1.10 – Oracle Scheduler Architecture

The basic architecture of Oracle 9i and Oracle 10g schedulers may be similar, but the functionality and associated APIs are quite different.  The Oracle 9i scheduler is extremely basic and a little clumsy, while the Oracle 10g scheduler is packed with features allowing job scheduling to be as simple or complicated as desired.  The original scheduler API has been retained in Oracle 10g for backwards compatibility, and it is this scheduler that will be focused on first.