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From maisnam ns <maisnam...@gmail.com>
Subject Re: Few noob MR questions
Date Sat, 13 Apr 2013 20:36:08 GMT
@Vjeran , running hadoop command over java adds the Hadoop libraries and
their dependencies to the classpath and brings in all the Hadoop
configuration details, the former does not . There's an excellent book on
Hadoop call the Hadoop the Definitive Guide by Tom White, everything is
explained in that book.

Regards
Niranjan Singh


On Sun, Apr 14, 2013 at 1:49 AM, Vjeran Marcinko <
vjeran.marcinko@email.t-com.hr> wrote:

> Hello,****
>
> ** **
>
> I am complete Hadoop and MR newbiew, so please help me with following…****
>
> ** **
>
> I can see that primary way to submit Hadoop MR job is via following
> command (wordcount example):****
>
> ** **
>
> hadoop jar wordcount.jar org.mycompany.WordCount****
>
> ** **
>
> **1.    **Although, looking at all MR examples out there, I see this
> „hadooo jar“ command used for submitting MR jobs, but actually it has
> nothing specific with MR job submissions, it just calls static „main“
> method, similar to plain „java“ command, and this main method can just
> print „Hello world“ on console and have no business with MR framework,
> right?****
>
> **2.    **If above is true, and I assume it is, what is the difference
> with using plain java –jar in place of  „hadoop jar“? Both call static
> „main“ method, and this method could submit MR job via JobClient class,
> right?****
>
> **3.    **On Hadoop docs (
> http://hadoop.apache.org/docs/r1.0.4/commands_manual.html#Generic+Options ),
> I see that –libjars options is only present in „hadoop job“ command, but
> not in „hadoop jar“, and later is usually used (for some unknown reason
> because former also has –submit ooption?) for submitting jobs, so my
> question is does that mean that when using „jar“ command I should only
> priovde thrid-party libs via „fat jar“?****
>
> ** **
>
> Regards,****
>
> Vjeran ****
>

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