Snapshot refresh DBMS Jobs

Question

Hello,
I have a snapshot scheduled to refresh every hour. I have noticed that job is actually not running every hour. Here is an example of what i am trying to explain.
DECLARE
X NUMBER;
BEGIN
SYS.DBMS_JOB.SUBMIT
( job => X
,what => 'dbms_refresh.refresh(''"Schema"."FLODS_RENEW_MV"'');'
,next_date => TO_DATE('08/08/2006 09:22:00','dd/mm/yyyy hh24:mi:ss')
,INTERVAL => 'SYSDATE+1/24 '
,no_parse => TRUE
SYS.DBMS_OUTPUT.PUT_LINE('Job Number is: ' || TO_CHAR(x));
END;
COMMIT;
This runs approximately for 3 mins. And i noticed today that the next_date changed the time to next_date => TO_DATE('08/08/2006 10:25:00','dd/mm/yyyy hh24:mi:ss').
So, is there any way to schedule a job every hour? Insted of every hour after the job finished executing?
Thanks

Answer 1

Hi,
This is one of the good reasons for using dbms_scheduler instead of dbms_job. dbms_scheduler supports a calendar syntax (actually a modified iCal RFC 2445 standard) for scheduling at regular intervals. The following job skeleton runs every hour at 22 mins after the hour starting immediately
begin
dbms_scheduler.create_job(
job_name=>'my_hourly_job',
job_type=>'plsql_block',
job_action=>'my_proc();',
repeat_interval=>'freq=hourly;byminute=22;bysecond=0',
enabled=>true , auto_drop=>true
end;
This is much clearer than using an ugly PL/SQL time function with TRUNC . It also deals automatically with daylight savings time switchovers which is uncertain with the PL/SQL time function.
With the new calendar syntax there should really be no reason to revert to time functions.
Hope this helps,
Ravi.