i, I have been trying to do a word count programme, which emmits only 1 key value , ie the last key value pair in the input file using wordcount mapreduce programme. Here is the content of the input file in a directory : a.txt : ==== f f g h i i j k l l m r f f h h Content of b.txt ======== r r g h h h m m c c b b d d r f O/p should be : r 4 Here is my sample mapper code & reducer code for simple word count. Can anyone tell me what changes should I make to get th o/p like above : Mapper code: -------------------- public class WcMapper extends Mapper<LongWritable,Text,Text,IntWritable>{ private static final IntWritable one= new IntWritable(1); private final Text word=new Text(); public void map(LongWritable key,Text value, Context context ) throws IOException, InterruptedException { StringTokenizer st =new StringTokenizer(value.toString()); while(st.hasMoreTokens()){ word.set(st.nextToken()); context.write(word, one); } } } Reducer code : --------------------- public void reduce(Text key,Iterable<IntWritable> values, Context context ) throws IOException, InterruptedException{ int sum=0; for(IntWritable value:values){ sum+= value.get(); } context.write(key, new IntWritable(sum)); } }   Driver code:: ----------------------- public class WcDriver extends Configured implements Tool{ public static void main(String[] args) throws Exception { int status = ToolRunner.run(new WcDriver(), args); System.exit(status); } @Override public int run(String[] args) throws Exception { Configuration c1=new Configuration(); Job j1= new Job(c1,"woc"); j1.setJarByClass(WcDriver.class); j1.setMapperClass(WcMapper.class); j1.setReducerClass(WcReducer.class); j1.setInputFormatClass(TextInputFormat.class); j1.setOutputFormatClass(TextOutputFormat.class); j1.setOutputKeyClass(Text.class); j1.setOutputValueClass(IntWritable.class); FileInputFormat.addInputPath(j1, new Path(args[0])); FileOutputFormat.setOutputPath(j1, new Path(args[1])); FileSystem fs = FileSystem.newInstance(c1); if (fs.exists(new Path(args[1]))) { fs.delete(new Path(args[1]), true); } return j1.waitForCompletion(true) ? 0 : 1; } } Appreciate all help.Please help.... ... View more

Hi,   I have gone through this question., can anyone pls tell me the correct answer with explanation?   Which best describes how TextInputFormat processes input files and line breaks? A. Input file splits may cross line breaks. A line that crosses file splits is read by the RecordReader of the split that contains the beginning of the broken line. B. Input file splits may cross line breaks. A line that crosses file splits is read by the RecordReaders of both splits containing the broken line. C. The input file is split exactly at the line breaks, so each RecordReader will read a series of complete lines. D. Input file splits may cross line breaks. A line that crosses file splits is ignored. E. Input file splits may cross line breaks. A line that crosses file splits is read by the RecordReader of the split that contains the end of the broken line.     Thanks in advance ... View more