001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     *     http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    
019    package org.apache.hadoop.mapred.lib.db;
020    
021    import java.io.IOException;
022    import java.sql.Connection;
023    import java.sql.PreparedStatement;
024    import java.sql.SQLException;
025    
026    import org.apache.hadoop.classification.InterfaceAudience;
027    import org.apache.hadoop.classification.InterfaceStability;
028    import org.apache.hadoop.fs.FileSystem;
029    import org.apache.hadoop.mapred.JobConf;
030    import org.apache.hadoop.mapred.OutputFormat;
031    import org.apache.hadoop.mapred.RecordWriter;
032    import org.apache.hadoop.mapred.Reporter;
033    import org.apache.hadoop.mapreduce.MRJobConfig;
034    import org.apache.hadoop.mapreduce.TaskAttemptID;
035    import org.apache.hadoop.mapreduce.task.TaskAttemptContextImpl;
036    import org.apache.hadoop.util.Progressable;
037    
038    @InterfaceAudience.Public
039    @InterfaceStability.Stable
040    public class DBOutputFormat<K  extends DBWritable, V> 
041        extends org.apache.hadoop.mapreduce.lib.db.DBOutputFormat<K, V>
042        implements OutputFormat<K, V> {
043    
044      /**
045       * A RecordWriter that writes the reduce output to a SQL table
046       */
047      protected class DBRecordWriter extends 
048          org.apache.hadoop.mapreduce.lib.db.DBOutputFormat<K, V>.DBRecordWriter
049          implements RecordWriter<K, V> {
050    
051        protected DBRecordWriter(Connection connection, 
052          PreparedStatement statement) throws SQLException {
053          super(connection, statement);
054        }
055    
056        /** {@inheritDoc} */
057        public void close(Reporter reporter) throws IOException {
058          super.close(null);
059        }
060      }
061    
062      /** {@inheritDoc} */
063      public void checkOutputSpecs(FileSystem filesystem, JobConf job)
064      throws IOException {
065      }
066    
067    
068      /** {@inheritDoc} */
069      public RecordWriter<K, V> getRecordWriter(FileSystem filesystem,
070          JobConf job, String name, Progressable progress) throws IOException {
071        org.apache.hadoop.mapreduce.RecordWriter<K, V> w = super.getRecordWriter(
072          new TaskAttemptContextImpl(job, 
073                TaskAttemptID.forName(job.get(MRJobConfig.TASK_ATTEMPT_ID))));
074        org.apache.hadoop.mapreduce.lib.db.DBOutputFormat.DBRecordWriter writer = 
075         (org.apache.hadoop.mapreduce.lib.db.DBOutputFormat.DBRecordWriter) w;
076        try {
077          return new DBRecordWriter(writer.getConnection(), writer.getStatement());
078        } catch(SQLException se) {
079          throw new IOException(se);
080        }
081      }
082    
083      /**
084       * Initializes the reduce-part of the job with the appropriate output settings
085       * 
086       * @param job The job
087       * @param tableName The table to insert data into
088       * @param fieldNames The field names in the table.
089       */
090      public static void setOutput(JobConf job, String tableName, String... fieldNames) {
091        if(fieldNames.length > 0 && fieldNames[0] != null) {
092          DBConfiguration dbConf = setOutput(job, tableName);
093          dbConf.setOutputFieldNames(fieldNames);
094        } else {
095          if(fieldNames.length > 0)
096            setOutput(job, tableName, fieldNames.length);
097          else 
098            throw new IllegalArgumentException("Field names must be greater than 0");
099        }
100      }
101      
102      /**
103       * Initializes the reduce-part of the job with the appropriate output settings
104       * 
105       * @param job The job
106       * @param tableName The table to insert data into
107       * @param fieldCount the number of fields in the table.
108       */
109      public static void setOutput(JobConf job, String tableName, int fieldCount) {
110        DBConfiguration dbConf = setOutput(job, tableName);
111        dbConf.setOutputFieldCount(fieldCount);
112      }
113      
114      private static DBConfiguration setOutput(JobConf job, String tableName) {
115        job.setOutputFormat(DBOutputFormat.class);
116        job.setReduceSpeculativeExecution(false);
117    
118        DBConfiguration dbConf = new DBConfiguration(job);
119        
120        dbConf.setOutputTableName(tableName);
121        return dbConf;
122      }
123      
124    }