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--- courses:mapreduce-tutorial:step-3 [2012/01/24 21:11]
straka
+++ courses:mapreduce-tutorial:step-3 [2012/01/26 17:15]
straka
@@ Line 1: / Line 1: @@
 ====== MapReduce Tutorial : Basic mapper ======
-The simplest MR job consists of a mapper only.  The input data is divided in several parts, every processed by an independent mapper, and the results are collected in one directory, one file per mapper.
+The simplest Hadoop job consists of a mapper only.  The input data is divided in several parts, every processed by an independent mapper, and the results are collected in one directory, one file per mapper.
+The Hadoop framework silently handles failures. If a mapper task fails, another is executed and the input of the failed attempt is discarded.
 ===== Example Perl mapper =====
@@ Line 38: / Line 40: @@
 ===== Exercise =====
-To check that your Hadoop environment works, try running a MR job on ''/home/straka/wiki/cs-text'', which outputs only articles with names beginning with a (ignoring the case).
+To check that your Hadoop environment works, try running a MR job on ''/home/straka/wiki/cs-text'', which outputs only articles with names beginning with an ''A'' (ignoring the case). You can download the template {{:courses:mapreduce-tutorial:step-3-exercise.txt|step-3-exercise.pl}} and execute it using
+  rm -rf step-3-output perl step-3-exercise.pl run /home/straka/wiki/cs-text step-3-output
+{{.:step-3-solution.txt|Solution.pl}}
-{{.:step-3:exercise.txt|Solution.pl}}

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