Oracle dbms_scheduler: Can I create a job that will not overlap with itself?

Question

How can I ensure that a dbms_scheduler job will never have more than one instance running?

For example, if I have a job that is scheduled to run once a minute, but it actually runs for three minutes, I don't want a second and third instance of the job to start and run concurrently.

(note) I previously asked this question specifying that either dbms_scheduler or dbms_jobs solutions were acceptable. I have since learned that dbms_jobs does not work well on RAC, hence this dbms_scheduler-specific question. (end note)

Answer 1

yes, you can, this in fact is default behaviour. See Database Administrator’s Guide chapter 29 Scheduling Jobs with Oracle Scheduler

Immediately after a job starts, the repeat_interval is evaluated to determine the next scheduled execution time of the job. While this might arrive while the job is still running, a new instance of the job does not start until the current one completes.

Answer 2

Doesn't this accomplish the same thing that @Justin Cave did in the other thread?

BEGIN
DBMS_SCHEDULER.CREATE_JOB 
(
   job_name             => 'hr.employees_jobs',
   job_type             => 'PLSQL_BLOCK',
   job_action           => 'BEGIN proc_that_takes_3_minutes; END;',
   start_date           => systimestamp,  
   repeat_interval      => 'FREQ=MINUTELY;INTERVAL=1',
   enabled              =>  TRUE,
   comments             => 'Gather table stats on hr.employees'
) ;
END ;
/