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
019package org.apache.hadoop.mapreduce.lib.db;
020
021import java.sql.Connection;
022import java.sql.ResultSet;
023import java.sql.PreparedStatement;
024import java.sql.SQLException;
025
026import org.apache.hadoop.classification.InterfaceAudience;
027import org.apache.hadoop.classification.InterfaceStability;
028import org.apache.hadoop.conf.Configuration;
029
030/**
031 * A RecordReader that reads records from a MySQL table.
032 */
033@InterfaceAudience.Public
034@InterfaceStability.Evolving
035public class MySQLDBRecordReader<T extends DBWritable> extends DBRecordReader<T> {
036
037  public MySQLDBRecordReader(DBInputFormat.DBInputSplit split, 
038      Class<T> inputClass, Configuration conf, Connection conn, DBConfiguration dbConfig,
039      String cond, String [] fields, String table) throws SQLException {
040    super(split, inputClass, conf, conn, dbConfig, cond, fields, table);
041  }
042
043  // Execute statements for mysql in unbuffered mode.
044  protected ResultSet executeQuery(String query) throws SQLException {
045    statement = getConnection().prepareStatement(query,
046      ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
047    statement.setFetchSize(Integer.MIN_VALUE); // MySQL: read row-at-a-time.
048    return statement.executeQuery();
049  }
050}