Need a better answer for "how many reduces?"
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Key: MAPREDUCE-1206
URL: https://issues.apache.org/jira/browse/MAPREDUCE-1206
Project: Hadoop Map/Reduce
Issue Type: Bug
Reporter: Allen Wittenauer
http://hadoop.apache.org/common/docs/current/mapred_tutorial.html#Reducer
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How Many Reduces?
The right number of reduces seems to be 0.95 or 1.75 multiplied by (<no. of
nodes> * mapred.tasktracker.reduce.tasks.maximum).
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Sure, if you only ever run one job on your grid. There should really be a
better answer here, especially explaining what the impact is of a high/low
number when chaining multiple map/reduce jobs.
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