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Both sides previous revision Previous revision Next revision | Previous revision Next revision Both sides next revision | ||
courses:mapreduce-tutorial:step-3 [2012/01/24 21:22] straka |
courses:mapreduce-tutorial:step-3 [2012/01/28 11:32] majlis Commands for execution were added. |
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====== MapReduce Tutorial : Basic mapper ====== | ====== MapReduce Tutorial : Basic mapper ====== | ||
- | The simplest | + | The simplest |
+ | |||
+ | 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 ===== | ===== Example Perl mapper ===== | ||
- | <file perl mapper.pl> | + | <file perl> |
# | # | ||
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The values '' | The values '' | ||
- | Resulting script can be executed locally | + | Resulting script can be executed locally |
perl script.pl run input_directory output_directory | perl script.pl run input_directory output_directory | ||
All files in input_directory are processes. The output_directory must not exist. | All files in input_directory are processes. The output_directory must not exist. | ||
Line 38: | Line 40: | ||
===== Exercise ===== | ===== Exercise ===== | ||
- | To check that your Hadoop environment works, try running a MR job on ''/ | + | To check that your Hadoop environment works, try running a MR job on ''/ |
+ | wget --no-check-certificate ' | ||
+ | rm -rf step-3-out-ex; | ||
+ | less step-3-out-ex/ | ||
+ | |||
+ | ==== Solution ==== | ||
+ | You can also download the solution {{: | ||
+ | wget --no-check-certificate ' | ||
+ | rm -rf step-3-out-sol; | ||
+ | less step-3-out-sol/ | ||
- | {{.: |