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courses:mapreduce-tutorial:step-12 [2012/01/28 23:09]
majlis Added links to previous and next chapter. 		courses:mapreduce-tutorial:step-12 [2012/01/31 09:39] (current)
straka Change Perl commandline syntax.
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 ===== Reduce-less jobs ===== ===== Reduce-less jobs =====
 If a MR job runs without reducers, the output of mappers is written to output directory without further processing. In this case, environmental variable ''HADOOP_WORK_OUTPUT_PATH'' is present even in a mapper and the files created in this directory are copied to the job output directory. If a MR job runs without reducers, the output of mappers is written to output directory without further processing. In this case, environmental variable ''HADOOP_WORK_OUTPUT_PATH'' is present even in a mapper and the files created in this directory are copied to the job output directory.
 +
  
 ===== Exercise ===== ===== Exercise =====
-Change the word counting script {{:courses:mapreduce-tutorial:TODOstep-5-solution1.txt|TODOwc.pl}} to produce results in reducers manually using the mentioned environmental variables, and execute it using four reducers.+Change the word counting script {{:courses:mapreduce-tutorial:step-5-solution1.txt|step-12-exercise.pl}} to produce results in reducers manually using the mentioned environmental variables, and execute it using four reducers.
  
-{{:courses:mapreduce-tutorial:step-12-solution.txt|Solution.pl}}+  wget --no-check-certificate 'https://wiki.ufal.ms.mff.cuni.cz/_media/courses:mapreduce-tutorial:step-5-solution1.txt' -O 'step-12-exercise.pl' 
 +  # NOW EDIT THE FILE 
 +  # $EDITOR step-12-exercise.pl 
 +  rm -rf step-12-out-ex; perl step-12-exercise.pl -c 4 -r 4 /home/straka/wiki/cs-text-medium/ step-12-out-ex 
 +  less step-12-out-ex/part-*
  
 +==== Solution ====
 +You can also download the solution {{:courses:mapreduce-tutorial:step-12-solution.txt|step-12-solution.pl}} and check the correct output.
 +  wget --no-check-certificate 'https://wiki.ufal.ms.mff.cuni.cz/_media/courses:mapreduce-tutorial:step-12-solution.txt' -O 'step-12-solution.pl'
 +  # NOW VIEW THE FILE
 +  # $EDITOR step-12-solution.pl
 +  rm -rf step-12-out-sol; perl step-12-solution.pl -c 4 -r 4 /home/straka/wiki/cs-text-medium/ step-12-out-sol
 +  less step-12-out-sol/vystup-*
  
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 </table> </table>
 </html> </html>
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