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.mapreduce.lib.db;
020
021 import java.sql.Connection;
022 import java.sql.ResultSet;
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.conf.Configuration;
029
030 /**
031 * A RecordReader that reads records from a MySQL table.
032 */
033 @InterfaceAudience.Public
034 @InterfaceStability.Evolving
035 public 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 }