HBase:Map Reduce on HBase : Scanning HBase Table using Map Reduce

Following the example Map Reduce Program , that helps to scan Table on HBase. Here , I have not used Reducer because requirement has  been fulfilled  in Mapper only. This Map Reduce Program is scanning a table on Hbase and writing it in a file on HDFS.

Here, I have used default Mapper Class. TableMapper can also be used for accessing Hbase Table.

Following is the driver class:

public class ScanTableDriver {

    public static void main(String[] args) throws IOException, InterruptedException, ClassNotFoundException

     {

         Configuration conf= new Configuration();

         Job job = new Job(conf);

        job.setJarByClass(ScanTableDriver.class);

        job.setMapperClass(ScanTableMapper.class);

        job.setOutputKeyClass(Text.class);

        job.setOutputValueClass(NullWritable.class);

        job.setInputFormatClass(TableInputFormat.class);

        job.getConfiguration().set(TableInputFormat.INPUT_TABLE, "employee"); // here employee is the name of the table

        FileOutputFormat.setOutputPath(job, new Path("hdfs: //namenode:address/filename"));

        System.exit(job.waitForCompletion(true)?0:1);        

     }    

}

Following is the Mapper class:

public class ScanTableMapper extends Mapper

{

      Text row=new Text();

    NullWritable val = NullWritable.get();

    

    public void map(Object key, Result value,Context context)

 {

        row.set(value.toString());

        try {

        context.write(row, val);

    }

catch (IOException e)

    {

               e.printStackTrace();

    }

catch (InterruptedException e)

    {

               e.printStackTrace();

    }

    

}