Sample MapReduce Code

Sample MapReduce Code

import com.emc.greenplum.gpdb.hadoop.io.GPDBWritable;
import com.emc.greenplum.gpdb.hadoop.mapreduce.lib.input.GPDBInputFormat;
import com.emc.greenplum.gpdb.hadoop.mapreduce.lib.output.GPDBOutputFormat;
import java.io.*;
import java.util.*;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.conf.*;
import org.apache.hadoop.io.*;
import org.apache.hadoop.mapreduce.*;
import org.apache.hadoop.mapreduce.lib.output.*;
import org.apache.hadoop.mapreduce.lib.input.*;
import org.apache.hadoop.util.*;

public class demoMR {

/*
 * Helper routine to create our generic record. This section shows the
 * format of the data. Modify as necessary. 
 */
 public static GPDBWritable generateGenericRecord() throws
      IOException {
 int[] colType = new int[3];
 colType[0] = GPDBWritable.BIGINT;
 colType[1] = GPDBWritable.BOOLEAN;
 colType[2] = GPDBWritable.VARCHAR;
 
  /*
   * This section passes the values of the data. Modify as necessary. 
   */ 
  GPDBWritable gw = new GPDBWritable(colType); 
  gw.setLong (0, (long)12345);  
  gw.setBoolean(1, true); 
  gw.setString (2, "abcdef");
  return gw; 
} 

/* 
 * DEMO Map/Reduce class test1
 * -- Regardless of the input, this section dumps the generic record
 * into GPDBFormat/
 */
 public static class Map_test1 
     extends Mapper<LongWritable, Text, LongWritable, GPDBWritable> {
 
  private LongWritable word = new LongWritable(1);

  public void map(LongWritable key, Text value, Context context) throws
       IOException { 
    try {
      GPDBWritable gw = generateGenericRecord();
      context.write(word, gw); 
      } 
      catch (Exception e) { 
        throw new IOException (e.getMessage()); 
      } 
    }
  }

  Configuration conf = new Configuration(true);
  Job job = new Job(conf, "test1");
  job.setJarByClass(demoMR.class);
  job.setInputFormatClass(TextInputFormat.class);
  job.setOutputKeyClass (LongWritable.class);
  job.setOutputValueClass (GPDBWritable.class);
  job.setOutputFormatClass(GPDBOutputFormat.class);
  job.setMapperClass(Map_test1.class);
  FileInputFormat.setInputPaths (job, new Path("/demo/data/tmp"));
  GPDBOutputFormat.setOutputPath(job, new Path("/demo/data/MRTest1"));
  job.waitForCompletion(true);
}