Suppose we have input file like below: $ vi uwserde kiju1233,1234567890 huhuhuhu,1233330987 … … … This input file consist of sessionid and timestamp as comma-separated value. Assuming this I wrote a WritableComparable as below: package hive; import java.io.DataInput; import java.io.DataOutput; import java.io.IOException; import org.apache.hadoop.io.LongWritable; import org.apache.hadoop.io.Text; import org.apache.hadoop.io.WritableComparable; public class UserWritable implements WritableComparable< UserWritable > { private Text sessionID ; private Text timestamp ; public UserWritable() { set( new Text(), new Text()); } public void set(Text sessionID, Text timestamp) { this . sessionID = sessionID; this . timestamp = timestamp; }