| /** |
| * 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.sqoop.manager; |
| |
| import java.io.IOException; |
| import java.sql.PreparedStatement; |
| import java.sql.ResultSet; |
| import java.sql.SQLException; |
| import java.util.ArrayList; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.sqoop.ImportOptions; |
| import org.apache.hadoop.sqoop.util.ImportError; |
| |
| /** |
| * Manages connections to MySQL databases |
| */ |
| public class MySQLManager extends GenericJdbcManager { |
| |
| public static final Log LOG = LogFactory.getLog(MySQLManager.class.getName()); |
| |
| // driver class to ensure is loaded when making db connection. |
| private static final String DRIVER_CLASS = "com.mysql.jdbc.Driver"; |
| |
| // set to true after we warn the user that we can use direct fastpath. |
| private static boolean warningPrinted = false; |
| |
| public MySQLManager(final ImportOptions opts) { |
| super(DRIVER_CLASS, opts); |
| } |
| |
| protected MySQLManager(final ImportOptions opts, boolean ignored) { |
| // constructor used by subclasses to avoid the --direct warning. |
| super(DRIVER_CLASS, opts); |
| } |
| |
| @Override |
| protected String getColNamesQuery(String tableName) { |
| // Use mysql-specific hints and LIMIT to return fast |
| return "SELECT t.* FROM " + tableName + " AS t LIMIT 1"; |
| } |
| |
| @Override |
| public String[] listDatabases() { |
| // TODO(aaron): Add an automated unit test for this. |
| |
| ResultSet results; |
| try { |
| results = execute("SHOW DATABASES"); |
| } catch (SQLException sqlE) { |
| LOG.error("Error executing statement: " + sqlE.toString()); |
| return null; |
| } |
| |
| try { |
| ArrayList<String> databases = new ArrayList<String>(); |
| while (results.next()) { |
| String dbName = results.getString(1); |
| databases.add(dbName); |
| } |
| |
| return databases.toArray(new String[0]); |
| } catch (SQLException sqlException) { |
| LOG.error("Error reading from database: " + sqlException.toString()); |
| return null; |
| } finally { |
| try { |
| results.close(); |
| } catch (SQLException sqlE) { |
| LOG.warn("Exception closing ResultSet: " + sqlE.toString()); |
| } |
| } |
| } |
| |
| @Override |
| public void importTable(ImportJobContext context) |
| throws IOException, ImportError { |
| |
| // Check that we're not doing a MapReduce from localhost. If we are, point |
| // out that we could use mysqldump. |
| if (!MySQLManager.warningPrinted) { |
| String connectString = context.getOptions().getConnectString(); |
| |
| if (null != connectString && connectString.indexOf("//localhost") != -1) { |
| // if we're not doing a remote connection, they should have a LocalMySQLManager. |
| // TODO(aaron): After LocalMySQLManager supports --host/--port, this should |
| // always be issued. |
| LOG.warn("It looks like you are importing from mysql on"); |
| LOG.warn("localhost. This transfer can be faster! Use the"); |
| LOG.warn("--direct option to exercise a MySQL-specific fast"); |
| LOG.warn("path."); |
| |
| MySQLManager.warningPrinted = true; // don't display this twice. |
| } |
| } |
| |
| // Then run the normal importTable() method. |
| super.importTable(context); |
| } |
| |
| /** |
| * Executes an arbitrary SQL statement. Sets mysql-specific parameter |
| * to ensure the entire table is not buffered in RAM before reading |
| * any rows. A consequence of this is that every ResultSet returned |
| * by this method *MUST* be close()'d, or read to exhaustion before |
| * another query can be executed from this ConnManager instance. |
| * |
| * @param stmt The SQL statement to execute |
| * @return A ResultSet encapsulating the results or null on error |
| */ |
| protected ResultSet execute(String stmt, Object... args) throws SQLException { |
| PreparedStatement statement = null; |
| statement = this.getConnection().prepareStatement(stmt, |
| ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY); |
| statement.setFetchSize(Integer.MIN_VALUE); // MySQL: read row-at-a-time. |
| if (null != args) { |
| for (int i = 0; i < args.length; i++) { |
| statement.setObject(i + 1, args[i]); |
| } |
| } |
| |
| LOG.info("Executing SQL statement: " + stmt); |
| return statement.executeQuery(); |
| } |
| } |
| |