edu.yale.cs.hadoopdb.benchmark.SelectionTaskDB.java Source code

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Here is the source code for edu.yale.cs.hadoopdb.benchmark.SelectionTaskDB.java

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/**
 * Copyright 2009 HadoopDB Team (http://db.cs.yale.edu/hadoopdb/hadoopdb.html)
 *
 * Licensed 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 edu.yale.cs.hadoopdb.benchmark;

import java.io.IOException;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.FileOutputFormat;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.MapReduceBase;
import org.apache.hadoop.mapred.Mapper;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.TextOutputFormat;
import org.apache.hadoop.util.ToolRunner;

import edu.yale.cs.hadoopdb.connector.DBConst;
import edu.yale.cs.hadoopdb.connector.DBWritable;
import edu.yale.cs.hadoopdb.exec.DBJobBase;
import edu.yale.cs.hadoopdb.util.HDFSUtil;

/**
 * HadoopDB's implementation of Selection Task
 * http://database.cs.brown.edu/projects/mapreduce-vs-dbms/
 */
public class SelectionTaskDB extends DBJobBase {

    public static final String PAGE_RANK_VALUE_PARAM = "page.rank.value";

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

    @Override
    protected JobConf configureJob(String... args) throws Exception {

        JobConf conf = new JobConf(this.getClass());
        conf.setJobName("selection_db");

        conf.setOutputKeyClass(Text.class);
        conf.setOutputValueClass(IntWritable.class);
        conf.setOutputFormat(TextOutputFormat.class);

        conf.setMapperClass(Map.class);
        conf.setNumReduceTasks(0);

        if (args.length < 2) {
            throw new RuntimeException("Incorrect arguments provided for " + this.getClass());
        }

        conf.set(PAGE_RANK_VALUE_PARAM, args[0]);

        // OUTPUT properties
        Path outputPath = new Path(args[1]);
        HDFSUtil.deletePath(outputPath);
        FileOutputFormat.setOutputPath(conf, outputPath);

        conf.set(DBConst.DB_RELATION_ID, "Rankings");
        conf.set(DBConst.DB_RECORD_READER, RankingsRecord.class.getName());
        conf.set(DBConst.DB_SQL_QUERY, "SELECT pageURL, pageRank FROM Rankings " + "WHERE pageRank > "
                + conf.get(PAGE_RANK_VALUE_PARAM) + ";");

        return conf;
    }

    @Override
    protected int printUsage() {
        System.out.println("<page_rank_value> <output_dir>");
        return -1;
    }

    static class Map extends MapReduceBase implements Mapper<LongWritable, RankingsRecord, Text, IntWritable> {

        protected Text outputKey = new Text();
        protected IntWritable outputValue = new IntWritable();

        public void map(LongWritable key, RankingsRecord value, OutputCollector<Text, IntWritable> output,
                Reporter reporter) throws IOException {

            outputKey.set(value.getPageURL());
            outputValue.set(value.getPageRank());
            output.collect(outputKey, outputValue);

        }
    }

    static class RankingsRecord implements DBWritable {
        private String pageURL;
        private int pageRank;

        public String getPageURL() {
            return pageURL;
        }

        public int getPageRank() {
            return pageRank;
        }

        @Override
        public void readFields(ResultSet resultSet) throws SQLException {
            this.pageURL = resultSet.getString("pageURL");
            this.pageRank = resultSet.getInt("pageRank");
        }

        @Override
        public void write(PreparedStatement statement) throws SQLException {
            throw new UnsupportedOperationException("No write() impl.");
        }
    }

}