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disadvantages of using job sequencer

Posted: Wed Nov 18, 2009 6:22 am
by dnat
Hi,

Can anyone tell what are the disadvantages of using a job sequencer..

Actually we have the scheduling tool, so i am planning to have separate ETL jobs called from the scheduling tool..but we can have one job sequencer to call all the jobs and execute..I feel restartability is little complex using job sequencer..

Posted: Wed Nov 18, 2009 6:25 am
by ray.wurlod
What's your alternative that you believe not to be as complex as a sequence job?

(The terminology is "sequence" - a "sequencer" is something you use IN a sequence job.)

Posted: Wed Nov 18, 2009 7:12 am
by chulett
You are in for a world of hurt if you plan on having your Enterprise scheduling tool running hundreds or thousands of individual jobs, enforcing dependencies, error handling, restarts and the like. :shock:

If you've got nothing else, there is no disadvantage to sequence jobs and their restartability can be as simple or as complex as you want to make it. Now, if you are running a version of 7.x earlier than say 7.5 I may need to revise that answer. :wink:

And for Ray, while we love to nit-pick on the 'sequence job' versus 'sequencer stage in a sequence job' subject, you do need to recognize that the official documentation names them as equal part sequence, sequence job, job sequence and job sequencer. From the 8.1 docs:

"WebSphere DataStage provides a graphical Job Sequencer which allows you to specify a sequence of parallel jobs or server jobs to run."

I tend to cut people more slack on that unless their usage is actually confusing.

Posted: Wed Nov 18, 2009 4:11 pm
by ray.wurlod
It's OK, I spread the joy. I do harangue IBM about errors in their manuals. They claim to welcome the feedback. Sometimes the changes even make it into the next edition!

Posted: Thu Nov 19, 2009 5:05 am
by kduke
The built in restartability is weak in a sequence job. You can improve it on your own. If you get more than 20 jobs in a sequence then it can get ugly.

The visual representation in a sequence is good document all by itself.