Join.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 com.aliyun.odps.mapred.open.example;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

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.utils.InputUtils;
import com.aliyun.odps.mapred.utils.OutputUtils;
import com.aliyun.odps.mapred.utils.SchemaUtils;

/**
 * Join, mr_join_src1/mr_join_src2(key bigint, value string), mr_join_out(key bigint, value1 string,
 * value2 string)
 * 
 */
public class Join {

  public static final Log LOG = LogFactory.getLog(Join.class);

  public static class JoinMapper extends MapperBase {

    private Record mapkey;
    private Record mapvalue;
    private long tag;

    @Override
    public void setup(TaskContext context) throws IOException {
      mapkey = context.createMapOutputKeyRecord();
      mapvalue = context.createMapOutputValueRecord();
      tag = context.getInputTableInfo().getLabel().equals("left") ? 0 : 1;
    }

    @Override
    public void map(long key, Record record, TaskContext context) throws IOException {
      mapkey.set(0, record.get(0));
      mapkey.set(1, tag);

      for (int i = 1; i < record.getColumnCount(); i++) {
        mapvalue.set(i - 1, record.get(i));
      }
      context.write(mapkey, mapvalue);
    }

  }

  public static class JoinReducer 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 {
      long k = key.getBigint(0);
      List<Object[]> leftValues = new ArrayList<Object[]>();

      while (values.hasNext()) {
        Record value = values.next();
        long tag = (Long) key.get(1);

        if (tag == 0) {
          leftValues.add(value.toArray().clone());
        } else {
          for (Object[] leftValue : leftValues) {
            int index = 0;
            result.set(index++, k);
            for (int i = 0; i < leftValue.length; i++) {
              result.set(index++, leftValue[i]);
            }
            for (int i = 0; i < value.getColumnCount(); i++) {
              result.set(index++, value.get(i));
            }
            context.write(result);
          }
        }
      }

    }

  }

  public static void main(String[] args) throws Exception {
    if (args.length != 3) {
      System.err.println("Usage: Join <input table1> <input table2> <out>");
      System.exit(2);
    }
    JobConf job = new JobConf();

    job.setMapperClass(JoinMapper.class);
    job.setReducerClass(JoinReducer.class);

    job.setMapOutputKeySchema(SchemaUtils.fromString("key:bigint,tag:bigint"));
    job.setMapOutputValueSchema(SchemaUtils.fromString("value:string"));

    job.setPartitionColumns(new String[] {"key"});
    job.setOutputKeySortColumns(new String[] {"key", "tag"});
    job.setOutputGroupingColumns(new String[] {"key"});
    job.setNumReduceTasks(1);

    InputUtils.addTable(TableInfo.builder().tableName(args[0]).label("left").build(), job);
    InputUtils.addTable(TableInfo.builder().tableName(args[1]).label("right").build(), job);
    OutputUtils.addTable(TableInfo.builder().tableName(args[2]).build(), job);

    JobClient.runJob(job);
  }

}