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MapReduce >> mail # user >> Re: Multi-stage map/reduce jobs


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Bertrand Dechoux 2012-11-24, 11:56
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Sean McNamara 2012-11-23, 22:22
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Re: Multi-stage map/reduce jobs
Hadoop is not an API for orchestrating mapreduce jobs- fortunately, there is no need for such an API.  Each mapreduce job can simple be run like a normal java class.

So, to run multiple mapreduce jobs?

Easy- you create a main()[] method in a single class which runs each job individually by invoking each job separately, using the waitForCompletion() method which blocks until a job completes.  

..this method will block until each individual job completes.

Jay Vyas
http://jayunit100.blogspot.com

On Nov 23, 2012, at 5:22 PM, Sean McNamara <[EMAIL PROTECTED]> wrote:

> It's not clear to me how to stitch together multiple map reduce jobs.  Without using cascading or something else like it, is the method basically to write to a intermediate spot, and have the next stage read from there?
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> If so, how are jobs responsible for cleaning up the temp/intermediate data they create?  What happens if stage 1 completes, and state 2 doesn't, do the stage 1 files get left around?
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> Does anyone have some insight they could share?
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> Thanks.