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From th.ced...@free.fr
Subject Problem MapReduce Total Sort, Word Count example
Date Thu, 03 Sep 2015 15:51:31 GMT
I want to do a total sort in mapreduce Word Count.

public int run(String[] args) throws Exception {
  Job job = Job.getInstance(getConf(), "wordcount");
  job.setJarByClass(this.getClass());
  FileInputFormat.addInputPath(job, new Path(args[0]));
  FileOutputFormat.setOutputPath(job, new Path(args[1]));
  job.setMapperClass(Map.class);

  //Total Sort
  job.setPartitionerClass(TotalOrderPartitioner.class);
  InputSampler.Sampler<Text, IntWritable> sampler = new InputSampler.RandomSampler<Text,
IntWritable>(0.1, 10000, 10);
  InputSampler.writePartitionFile(job, sampler);
  Path inputDir = new Path(args[2] + "/_tmp");
  Path partitionFile = new Path(inputDir, "_partitioning");
  TotalOrderPartitioner.setPartitionFile(job.getConfiguration(),partitionFile);
  InputSampler.writePartitionFile(job, sampler);

  job.setReducerClass(Reduce.class);
  job.setOutputKeyClass(Text.class);
  job.setOutputValueClass(IntWritable.class);  

  return job.waitForCompletion(true) ? 0 : 1;
}

But i get an error java.io.IOException: wrong key class: org.apache.hadoop.io.Text is not
class org.apache.hadoop.io.LongWritable

Does the InputSampler.RandomSampler only work for FloatWritable ? if not how can do a total
sort in mapreduce ?

Thanks,
Cedric

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