want input sampler & sorted partitioner
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Key: HADOOP-3019
URL: https://issues.apache.org/jira/browse/HADOOP-3019
Project: Hadoop Core
Issue Type: New Feature
Components: mapred
Reporter: Doug Cutting
The input sampler should generate a small, random sample of the input, saved to
a file.
The partitioner should read the sample file and partition keys into relatively
even-sized key-ranges, where the partition numbers correspond to key order.
Note that when the sampler is used for partitioning, the number of samples
required is proportional to the number of reduce partitions. 10x the intended
reducer count should give good results.
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