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Sqoop, mail # user - Calling Sqoop incremental job from Map/Reduce code


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Artem Ervits 2013-02-12, 15:26
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Jarek Jarcec Cecho 2013-02-12, 15:44
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RE: Calling Sqoop incremental job from Map/Reduce code
Artem Ervits 2013-02-21, 17:49
Thank you Jarek, I can now see where I went wrong with my idea.

-----Original Message-----
From: Jarek Jarcec Cecho [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, February 12, 2013 10:44 AM
To: [EMAIL PROTECTED]
Subject: Re: Calling Sqoop incremental job from Map/Reduce code

Hi Artem,
would you mind describe your use case in a more details? I'm especially interested to know more about what do you mean by executing from map/reduce program.

Sqoop itself will span a mapreduce job, so executing it from another map/reduce job do not make much sense as you would get exponencial load. Imagine 50 mappers where each will span Sqoop job that will again span 50 mappers, thats 50 * 50 = 2500 running map tasks that most likely would kill your remote database. Thus it might be more appropriate to execute Sqoop prior running your mapreduce job as you've mentioned that you're already doing.

About your question whether Sqoop needs to be installed on each node, it do not. Hadoop is providing facility called DistributedCache [1] that allows you to distribute arbitrary files with your job. The benefit is that jars will be automatically added to application classpath.

Jarcec

Links:
1: http://hadoop.apache.org/docs/current/api/org/apache/hadoop/filecache/DistributedCache.html

On Tue, Feb 12, 2013 at 03:26:50PM +0000, Artem Ervits wrote:
> Hello all,
>
> I'd like to know if there's a way to execute an incremental job from a map/reduce program. If there is a way, please point to a user guide I can take a look at to achieve it. In case it is possible, does Sqoop need to be installed on every node of the Hadoop cluster? I'm aware of the fact that Oozie would be able to achieve this but I was wondering if there are other ways. Right now I have a script that first calls the Sqoop job and then executes the M/R job.
>
> Thank you.
>
> Artem Ervits
> New York Presbyterian Hospital
>
>
>
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