How & When does the Scheduler calculates the next run of the job?

Question

I have created 3 jobs (J1, J2, J3). All of these are using same named schedule. My concept is that all the jobs should run on the same time according to the repeat interval of the schedule but it doesnt happen. When i alter the scheduler information, only one job's next run time gets updated and the rest of two keep on containing the older values. This results in only one of the job to be running on the next recurrence. Is it a known issue,..or am i getting anything wrong?

Answer 1

I ran the test and not found issue.
begin
--dbms_scheduler.drop_job(job_name => 'j1');
--dbms_scheduler.drop_job(job_name => 'j2');
--dbms_scheduler.drop_job(job_name => 'j3');
DBMS_SCHEDULER.CREATE_SCHEDULE
(schedule_name => 'TEST_SCHED',
start_date=> sysdate,
end_date => null,
repeat_interval=> 'FREQ=DAILY',
comments=>NULL);
DBMS_SCHEDULER.create_job(job_name => 'j1',
job_type => 'PLSQL_BLOCK',
job_action => 'declare a number begin select 1 into a from dual; end;',
schedule_name => 'TEST_SCHED',
comments => 'TEST');
DBMS_SCHEDULER.create_job(job_name => 'j2',
job_type => 'PLSQL_BLOCK',
job_action => 'declare a number begin select 1 into a from dual; end;',
schedule_name => 'TEST_SCHED',
comments => 'TEST');
DBMS_SCHEDULER.create_job(job_name => 'j3',
job_type => 'PLSQL_BLOCK',
job_action => 'declare a number begin select 1 into a from dual; end;',
schedule_name => 'TEST_SCHED',
comments => 'TEST');
end;
select job_name,next_run_date From user_scheduler_jobs
1     J3     *06-MAR-10* 05.28.59.600000 PM +07:00
2     J1     *06-MAR-10* 05.28.59.500000 PM +07:00
3     J2     *06-MAR-10* 05.28.59.700000 PM +07:00
begin
dbms_scheduler.set_attribute(name => 'TEST_SCHED',attribute => 'repeat_interval' ,value => 'FREQ=MINUTELY;INTERVAL=20');
end;
select job_name,next_run_date From user_scheduler_jobs
1     J3     *05-MAR-10* 05.48.59.000000 PM +07:00
2     J1     *05-MAR-10* 05.48.59.000000 PM +07:00
3     J2     *05-MAR-10* 05.48.59.000000 PM +07:00
try check job has been enabled.