Join.java
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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 org.apache.hadoop.examples;
- import java.io.IOException;
- import java.util.*;
- import org.apache.hadoop.conf.Configuration;
- import org.apache.hadoop.conf.Configured;
- import org.apache.hadoop.fs.Path;
- import org.apache.hadoop.io.BytesWritable;
- import org.apache.hadoop.io.Writable;
- import org.apache.hadoop.io.WritableComparable;
- import org.apache.hadoop.mapred.*;
- import org.apache.hadoop.mapred.join.*;
- import org.apache.hadoop.mapred.lib.IdentityMapper;
- import org.apache.hadoop.mapred.lib.IdentityReducer;
- import org.apache.hadoop.util.Tool;
- import org.apache.hadoop.util.ToolRunner;
- /**
- * This is the trivial map/reduce program that does absolutely nothing
- * other than use the framework to fragment and sort the input values.
- *
- * To run: bin/hadoop jar build/hadoop-examples.jar join
- * [-m <i>maps</i>] [-r <i>reduces</i>]
- * [-inFormat <i>input format class</i>]
- * [-outFormat <i>output format class</i>]
- * [-outKey <i>output key class</i>]
- * [-outValue <i>output value class</i>]
- * [-joinOp <inner|outer|override>]
- * [<i>in-dir</i>]* <i>in-dir</i> <i>out-dir</i>
- */
- public class Join extends Configured implements Tool {
- static int printUsage() {
- System.out.println("join [-m <maps>] [-r <reduces>] " +
- "[-inFormat <input format class>] " +
- "[-outFormat <output format class>] " +
- "[-outKey <output key class>] " +
- "[-outValue <output value class>] " +
- "[-joinOp <inner|outer|override>] " +
- "[input]* <input> <output>");
- ToolRunner.printGenericCommandUsage(System.out);
- return -1;
- }
- /**
- * The main driver for sort program.
- * Invoke this method to submit the map/reduce job.
- * @throws IOException When there is communication problems with the
- * job tracker.
- */
- public int run(String[] args) throws Exception {
- JobConf jobConf = new JobConf(getConf(), Sort.class);
- jobConf.setJobName("join");
- jobConf.setMapperClass(IdentityMapper.class);
- jobConf.setReducerClass(IdentityReducer.class);
- JobClient client = new JobClient(jobConf);
- ClusterStatus cluster = client.getClusterStatus();
- int num_maps = cluster.getTaskTrackers() *
- jobConf.getInt("test.sort.maps_per_host", 10);
- int num_reduces = (int) (cluster.getMaxReduceTasks() * 0.9);
- String sort_reduces = jobConf.get("test.sort.reduces_per_host");
- if (sort_reduces != null) {
- num_reduces = cluster.getTaskTrackers() *
- Integer.parseInt(sort_reduces);
- }
- Class<? extends InputFormat> inputFormatClass =
- SequenceFileInputFormat.class;
- Class<? extends OutputFormat> outputFormatClass =
- SequenceFileOutputFormat.class;
- Class<? extends WritableComparable> outputKeyClass = BytesWritable.class;
- Class<? extends Writable> outputValueClass = TupleWritable.class;
- String op = "inner";
- List<String> otherArgs = new ArrayList<String>();
- for(int i=0; i < args.length; ++i) {
- try {
- if ("-m".equals(args[i])) {
- num_maps = Integer.parseInt(args[++i]);
- } else if ("-r".equals(args[i])) {
- num_reduces = Integer.parseInt(args[++i]);
- } else if ("-inFormat".equals(args[i])) {
- inputFormatClass =
- Class.forName(args[++i]).asSubclass(InputFormat.class);
- } else if ("-outFormat".equals(args[i])) {
- outputFormatClass =
- Class.forName(args[++i]).asSubclass(OutputFormat.class);
- } else if ("-outKey".equals(args[i])) {
- outputKeyClass =
- Class.forName(args[++i]).asSubclass(WritableComparable.class);
- } else if ("-outValue".equals(args[i])) {
- outputValueClass =
- Class.forName(args[++i]).asSubclass(Writable.class);
- } else if ("-joinOp".equals(args[i])) {
- op = args[++i];
- } else {
- otherArgs.add(args[i]);
- }
- } catch (NumberFormatException except) {
- System.out.println("ERROR: Integer expected instead of " + args[i]);
- return printUsage();
- } catch (ArrayIndexOutOfBoundsException except) {
- System.out.println("ERROR: Required parameter missing from " +
- args[i-1]);
- return printUsage(); // exits
- }
- }
- // Set user-supplied (possibly default) job configs
- jobConf.setNumMapTasks(num_maps);
- jobConf.setNumReduceTasks(num_reduces);
- if (otherArgs.size() < 2) {
- System.out.println("ERROR: Wrong number of parameters: ");
- return printUsage();
- }
- FileOutputFormat.setOutputPath(jobConf,
- new Path(otherArgs.remove(otherArgs.size() - 1)));
- List<Path> plist = new ArrayList<Path>(otherArgs.size());
- for (String s : otherArgs) {
- plist.add(new Path(s));
- }
- jobConf.setInputFormat(CompositeInputFormat.class);
- jobConf.set("mapred.join.expr", CompositeInputFormat.compose(
- op, inputFormatClass, plist.toArray(new Path[0])));
- jobConf.setOutputFormat(outputFormatClass);
- jobConf.setOutputKeyClass(outputKeyClass);
- jobConf.setOutputValueClass(outputValueClass);
- Date startTime = new Date();
- System.out.println("Job started: " + startTime);
- JobClient.runJob(jobConf);
- Date end_time = new Date();
- System.out.println("Job ended: " + end_time);
- System.out.println("The job took " +
- (end_time.getTime() - startTime.getTime()) /1000 + " seconds.");
- return 0;
- }
- public static void main(String[] args) throws Exception {
- int res = ToolRunner.run(new Configuration(), new Join(), args);
- System.exit(res);
- }
- }