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courses:mapreduce-tutorial:step-9 [2012/01/25 16:16] straka |
courses:mapreduce-tutorial:step-9 [2012/01/25 16:17] straka |
| ''-r number_of_reducers'' | ''-Dmapred.reduce.tasks=number_of_reducers'' | | | ''-r number_of_reducers'' | ''-Dmapred.reduce.tasks=number_of_reducers'' | |
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===== Brief list of Hadoop options ===== | ===== A brief list of Hadoop options ===== |
^ Hadoop option ^ Default value ^ Description ^ | ^ Hadoop option ^ Default value ^ Description ^ |
| ''mapred.job.tracker'' | ? | Cluster master | | | ''mapred.job.tracker'' | ? | Cluster master | |
| ''mapred.reduce.tasks'' | 1 | Number of reducers | | | ''mapred.reduce.tasks'' | 1 | Number of reducers | |
| ''mapred.min.split.size'' | 1 | Minimum size of file split in bytes | | | ''mapred.min.split.size'' | 1 | Minimum size of file split in bytes | |
| ''mapred.max.split.size'' | 2^63-1 | Minimum size of file split in bytes | | | ''mapred.max.split.size'' | 2%%^%%63-1 | Minimum size of file split in bytes | |
| ''mapred.map.tasks.speculative.execution'' | true | If true, then multiple instances of some map tasks may be executed in parallel | | | ''mapred.map.tasks.speculative.execution'' | true | If true, then multiple instances of some map tasks may be executed in parallel | |
| ''mapred.reduce.tasks.speculative.execution'' | true | If true, then multiple instances of some reduce tasks may be executed in parallel | | | ''mapred.reduce.tasks.speculative.execution'' | true | If true, then multiple instances of some reduce tasks may be executed in parallel | |
| ''mapred.compress.map.output'' | false | Should the outputs of the maps be compressed before being sent across the network. Uses SequenceFile compression | | | ''mapred.compress.map.output'' | false | Should the outputs of the maps be compressed before being sent across the network. Uses SequenceFile compression | |
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A more complete list (but not exhaustive) can be found {{http://hadoop.apache.org/common/docs/r1.0.0/mapred-default.html|here}. | A more complete list (but not exhaustive) can be found [[http://hadoop.apache.org/common/docs/r1.0.0/mapred-default.html|here]]. |
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