Gist for Stack Overflow Q: http://stackoverflow.com/questions/19080287/whats-the-difference-between-mapred-and-mapreduce-packages-in-apache-avro

AvroWordCountNewAPI.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package csw;

import java.io.IOException;
import java.util.StringTokenizer;

import org.apache.avro.mapred.AvroKey;
import org.apache.avro.mapreduce.AvroJob;
import org.apache.avro.mapreduce.AvroKeyOutputFormat;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;

import csw.avro.WordCount;

/**
 * The classic WordCount example modified to output Avro Pair<CharSequence,
 * Integer> records instead of text
 * <p>
 * Adapted from
 * http://svn.apache.org/viewvc/avro/trunk/doc/examples/mr-example/src
 * /main/java/example/AvroWordCount.java?view=co and modified to use the new
 * Hadoop mapreduce API
 */
public class AvroWordCountNewAPI extends Configured implements Tool {

    public static class Map extends
            Mapper<LongWritable, Text, Text, IntWritable> {
        private final static IntWritable one = new IntWritable(1);
        private Text word = new Text();

        @Override
        public void map(LongWritable key, Text value, Context context)
                throws IOException, InterruptedException {
            String line = value.toString();
            StringTokenizer tokenizer = new StringTokenizer(line);
            while (tokenizer.hasMoreTokens()) {
                word.set(tokenizer.nextToken());
                context.write(word, one);
            }
        }
    }

    public static class Reduce extends
            Reducer<Text, IntWritable, AvroKey<WordCount>, NullWritable> {
        AvroKey<WordCount> outputKey = new AvroKey<WordCount>(new WordCount());

        @Override
        protected void reduce(Text key, Iterable<IntWritable> values,
                Context context) throws IOException, InterruptedException {
            int sum = 0;
            for (IntWritable value : values) {
                sum += value.get();
            }
            outputKey.datum().setWord(key.toString());
            outputKey.datum().setCount(sum);

            context.write(outputKey, null);
        }
    }

    public int run(String[] args) throws Exception {
        if (args.length != 2) {
            System.err
                    .println("Usage: AvroWordCountNewAPI <input path> <output path>");
            return -1;
        }

        Job conf = new Job(getConf());
        conf.setJobName("wordcount");
        conf.setJarByClass(AvroWordCountNewAPI.class);

        AvroJob.setOutputKeySchema(conf, WordCount.getClassSchema());

        conf.setMapperClass(Map.class);
        conf.setReducerClass(Reduce.class);

        conf.setInputFormatClass(TextInputFormat.class);
        conf.setOutputFormatClass(AvroKeyOutputFormat.class);

        conf.setMapOutputKeyClass(Text.class);
        conf.setMapOutputValueClass(IntWritable.class);
        
        conf.setOutputKeyClass(AvroKey.class);
        conf.setOutputValueClass(NullWritable.class);

        FileInputFormat.setInputPaths(conf, new Path(args[0]));
        FileOutputFormat.setOutputPath(conf, new Path(args[1]));

        return conf.waitForCompletion(true) ? 0 : 1;
    }

    public static void main(String[] args) throws Exception {
        int res = ToolRunner.run(new Configuration(),
                new AvroWordCountNewAPI(), args);
        System.exit(res);
    }
}

wc.avsc

{"namespace": "csw.avro",
 "type": "record",
 "name": "WordCount",
 "fields": [
     {"name": "word", "type": "string"},
     {"name": "count",  "type": "int"}
 ]
}