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   * 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 com.aliyun.odps.mapred.local;
  
  import java.io.IOException;
  import java.util.Iterator;
  
  import org.junit.Before;
  import org.junit.Test;
  
  import com.aliyun.odps.OdpsException;
  import com.aliyun.odps.data.Record;
  import com.aliyun.odps.data.TableInfo;
  import com.aliyun.odps.mapred.JobClient;
  import com.aliyun.odps.mapred.MapperBase;
  import com.aliyun.odps.mapred.ReducerBase;
  import com.aliyun.odps.mapred.conf.JobConf;
  import com.aliyun.odps.mapred.local.utils.TestUtils;
  import com.aliyun.odps.mapred.utils.InputUtils;
  import com.aliyun.odps.mapred.utils.OutputUtils;
  import com.aliyun.odps.mapred.utils.SchemaUtils;
  
  /**
   * This is an example ODPS Map/Reduce application. It reads the input table that
   * must contain two integers per record. The output is sorted by the first and
   * second number and grouped on the first number.
   *
   * To run: jar -libjars mapreduce-examples.jar -classpath
   * clt/lib/mapreduce-examples.jar
   * com.aliyun.odps.mapreduce.examples.SecondarySort <i>in-table</i>
   * <i>out-table</i>
   */
  public class SecondarySort {
  
    @Before
    public void setUp() throws Exception {
      TestUtils.setEnvironment(TestUtils.odps_test_openmr2);
    }
  
    /**
     * Read two integers from each line and generate a key, value pair as ((left,
     * right), right).
     */
    public static class MapClass extends MapperBase {
  
      private Record key;
      private Record value;
  
      @Override
      public void setup(TaskContext context) throws IOException {
        key = context.createMapOutputKeyRecord();
        value = context.createMapOutputValueRecord();
      }
  
      @Override
      public void map(long recordNum, Record record, TaskContext context) throws IOException {
        long left = 0;
        long right = 0;
  
        if (record.getColumnCount() > 0) {
          left = (Long) record.get(0);
          if (record.getColumnCount() > 1) {
            right = (Long) record.get(1);
          }
  
          key.set(new Object[]{(Long) left, (Long) right});
          value.set(new Object[]{(Long) right});
  
          context.write(key, value);
        }
      }
    }
  
    /**
     * A reducer class that just emits the sum of the input values.
     */
    public static class ReduceClass extends ReducerBase {
  
      private Record result = null;
  
      @Override
      public void setup(TaskContext context) throws IOException {
        result = context.createOutputRecord();
      }
  
      @Override
      public void reduce(Record key, Iterator<Record> values, TaskContext context)
          throws IOException {
        result.set(0, key.get(0));
        while (values.hasNext()) {
          Record value = values.next();
          result.set(1, value.get(0));
          context.write(result);
        }
      }
  
    }
  
    @Test
    public void test() throws OdpsException {
      String[] args = new String[2];
      args[0] = "mr_sort_in";
      args[1] = "mr_secondarysort_out";
  
      JobConf job = new JobConf();
      job.setMapperClass(MapClass.class);
      job.setReducerClass(ReduceClass.class);
  
      // compare first and second parts of the pair
      job.setOutputKeySortColumns(new String[]{"i1", "i2"});
  
      // partition based on the first part of the pair
      job.setPartitionColumns(new String[]{"i1"});
  
      // grouping comparator based on the first part of the pair
      job.setOutputGroupingColumns(new String[]{"i1"});
  
      // the map output is LongPair, Long
      job.setMapOutputKeySchema(SchemaUtils.fromString("i1:bigint,i2:bigint"));
      job.setMapOutputValueSchema(SchemaUtils.fromString("i2x:bigint"));
  
      InputUtils.addTable(TableInfo.builder().tableName(args[0]).build(), job);
      OutputUtils.addTable(TableInfo.builder().tableName(args[1]).build(), job);
  
      JobClient.runJob(job);
    }
  
  }
  