Question

I am currently working on a MapReduce Job which I am only using the mapper without the reducer. I do not need to write the key out because I only need the values which are stored in an array and want to write it out as my final output file. How can achieve this on Hadoop? Instead of writing to the output both the key and the value, I am only interested in writing out only the values. The values are in an array. Thanks

public void pfor(TestFor pfor,LongWritable key, Text value, Context context, int times) throws IOException, InterruptedException{
    int n = 0;
    while(n < times){
        pfor.pforMap(key,value, context);
        n++;
    }
    for(int i =0;i<uv.length; i++){
        LOG.info(uv[i].get() + " Final output");
    }
    IntArrayWritable edge = new IntArrayWritable();
    edge.set(uv);
    context.write(new IntWritable(java.lang.Math.abs(randGen.nextInt())), edge);        
    uv= null;
}

Answer 1

Use NullWritable as value and emit your “edge” as key.

https://hadoop.apache.org/docs/stable/api/org/apache/hadoop/io/NullWritable.html