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courses:mapreduce-tutorial:step-7 [2012/01/29 20:52] straka |
courses:mapreduce-tutorial:step-7 [2012/01/29 20:52] straka |
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| Remarks: | Remarks: | ||
| * The reducers seem to start running before the mappers finish. In the web interface, the running time of reducers is divided into thirds: | * The reducers seem to start running before the mappers finish. In the web interface, the running time of reducers is divided into thirds: | ||
| - | * during the first 33%, the mapper outputs are copied to the machine where reducer runs | + | * during the first 33%, the mapper outputs are copied to the machine where reducer runs. |
| - | * during the second 33%, the (key, value) pairs are sorted | + | * during the second 33%, the (key, value) pairs are sorted. |
| - | * during the last 33%, the user-defined reducer runs | + | * during the last 33%, the user-defined reducer runs. |
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