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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 20:06] straka |
courses:mapreduce-tutorial:step-3 [2012/01/28 12:03] majlis |
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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 ===== | ||
- | <code perl> | + | <file perl> |
# | # | ||
Line 28: | Line 30: | ||
$runner-> | $runner-> | ||
- | </code> | + | </file> |
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. | ||
- | ===== Exercise ===== | ||
- | To check that your Hadoop environment works, try running a MR job on ''/ | + | ---- |
+ | < | ||
+ | <table style=" | ||
+ | <tr> | ||
+ | <td style=" | ||
+ | <td style=" | ||
+ | <td style=" | ||
+ | </tr> | ||
+ | </ | ||
+ | </ |