Take control of Oracles queue with a step by step approach to getting rid of those pesky DBMS_JOBs.

Lets face it, Oracles job scheduling facility is a wonderful tool for scheduling Oracle related jobs without having to maintain a cron job on Unix or an AT job in windows. It is also very robust and reliable. It is that very reliability and robustness that gives many of us our problems.

If you have any form of jobs running on your system, you will at one time or another come across the issue of a run-away job that just doesnt seem to want to end. Or maybe you will try and shutdown the database only to find out that it is waiting to complete a job. I would like to offer some help in the management of those job queues when they just dont seem to want to end or go away.

A while back I needed to find information on how to clear the job queue for jobs running with no apparent end in sight. Some had hung, while others just were taking a bad access path to data. I needed to bring down these jobs, do a bit of tuning and then restart the jobs. Well, to my amazement, there wasnt very much information out on the web that gave good insight into this process. Basically the method suggested was to first break the job and then issue an ALTER SYTEM KILL SESSION command. This method does not always work and unfortunately--never on my system, for the jobs I had. I then called Oracle support and basically got the same answer as I found out on the web. They did give me one added piece of information. They said, if the ALTER SYSTEM KILL SESSION didnt work, I was supposed to bounce my database in order to bring down the job queue processes. First of all, this wasnt an option and when I did get the opportunity to bounce the database box, many of the jobs seemed to come right back as strong as ever.

Before writing this article I did another quick search on the topic of killing dbms_jobs and to my amazement there still wasnt much good information out there. This is why I want to share my method, so that you wont be stuck up against the wall with this problem and nowhere to turn, as I was.

Lets first go through a few different methods of viewing the information about job queues.

Viewing scheduled dbms_jobs

When looking at what jobs have been scheduled, there is really only one view that you need to go to. The dba_jobs view contains all of the information you need, to see what has been scheduled, when they were last run, and if they are currently running. Use the following simple script to take a look. Bear with me on the sub-select, I will build on this query as we go on in the presentation.

scheduled_dbms_jobs.sql

set linesize 250
col log_user       for a10
col job            for 9999999  head 'Job'
col broken         for a1       head 'B'
col failures       for 99       head "fail"
col last_date      for a18      head 'Last|Date'
col this_date      for a18      head 'This|Date'
col next_date      for a18      head 'Next|Date'
col interval       for 9999.000 head 'Run|Interval'
col what           for a60

select j.log_user,
     j.job,
     j.broken,
     j.failures,
     j.last_date||':'||j.last_sec last_date,
     j.this_date||':'||j.this_sec this_date,
     j.next_date||':'||j.next_sec next_date,
     j.next_date - j.last_date interval,
     j.what
from (select dj.LOG_USER, dj.JOB, dj.BROKEN, dj.FAILURES, 
             dj.LAST_DATE, dj.LAST_SEC, dj.THIS_DATE, dj.THIS_SEC, 
             dj.NEXT_DATE, dj.NEXT_SEC, dj.INTERVAL, dj.WHAT
        from dba_jobs dj) j;

What Jobs are Actually Running

A simple join to the dba_jobs_running view will give us a good handle on the scheduled jobs that are actually running at this time. This is done by a simple join through the job number. The new column of interest returned here is the sid which is the identifier of the process that is currently executing the job.

running_jobs.sql

set linesize 250
col sid            for 9999     head 'Session|ID'
col log_user       for a10
col job            for 9999999  head 'Job'
col broken         for a1       head 'B'
col failures       for 99       head "fail"
col last_date      for a18      head 'Last|Date'
col this_date      for a18      head 'This|Date'
col next_date      for a18      head 'Next|Date'
col interval       for 9999.000 head 'Run|Interval'
col what           for a60
select j.sid,
       j.log_user,
       j.job,
       j.broken,
       j.failures,
       j.last_date||':'||j.last_sec last_date,
       j.this_date||':'||j.this_sec this_date,
       j.next_date||':'||j.next_sec next_date,
       j.next_date - j.last_date interval,
       j.what
from (select djr.SID, 
             dj.LOG_USER, dj.JOB, dj.BROKEN, dj.FAILURES, 
             dj.LAST_DATE, dj.LAST_SEC, dj.THIS_DATE, dj.THIS_SEC, 
             dj.NEXT_DATE, dj.NEXT_SEC, dj.INTERVAL, dj.WHAT
        from dba_jobs dj, dba_jobs_running djr
       where dj.job = djr.job ) j;

What Sessions are Running the Jobs

Now that we have determined which jobs are currently running, we need to find which Oracle session and operating system process is accessing them. This is done through first joining v$process to v$session by way of paddr and addr which is the address of the processs that owns the sessions, and then joining the results back to the jobs running through the sid value. The new columns returned in our query are spid which is the operating system process identifier and serial# which is the session serial number.

session_jobs.sql

set linesize 250
col sid            for 9999     head 'Session|ID'
col spid                        head 'O/S|Process|ID'
col serial#        for 9999999  head 'Session|Serial#'
col log_user       for a10
col job            for 9999999  head 'Job'
col broken         for a1       head 'B'
col failures       for 99       head "fail"
col last_date      for a18      head 'Last|Date'
col this_date      for a18      head 'This|Date'
col next_date      for a18      head 'Next|Date'
col interval       for 9999.000 head 'Run|Interval'
col what           for a60
select j.sid,
s.spid,
s.serial#,
       j.log_user,
       j.job,
       j.broken,
       j.failures,
       j.last_date||':'||j.last_sec last_date,
       j.this_date||':'||j.this_sec this_date,
       j.next_date||':'||j.next_sec next_date,
       j.next_date - j.last_date interval,
       j.what
from (select djr.SID, 
             dj.LOG_USER, dj.JOB, dj.BROKEN, dj.FAILURES, 
             dj.LAST_DATE, dj.LAST_SEC, dj.THIS_DATE, dj.THIS_SEC, 
             dj.NEXT_DATE, dj.NEXT_SEC, dj.INTERVAL, dj.WHAT
        from dba_jobs dj, dba_jobs_running djr
       where dj.job = djr.job ) j,
     (select p.spid, s.sid, s.serial#
          from v$process p, v$session s
         where p.addr  = s.paddr ) s
 where j.sid = s.sid;

Now that we have a good handle on how we can look at the jobs and the key columns involved, let's go through the steps needed to bring down a job. The following is a 5 to 11 step process that should solve all of your problems.

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