8.9.7 A Complete Example: Working with Employee Data

The included program shows one possible way of working with sharded data relating to employees. To run this program, you must set up a shard mapping for the employees table in MySQL Fabric as described in Section 8.9.4, “MySQL Fabric Configuration for Running Samples”.

This code can be found in the distribution package in src/demo/fabric/EmployeesJdbc.java.

/*
  Copyright (c) 2013, 2014, Oracle and/or its affiliates. All rights reserved.

  The MySQL Connector/J is licensed under the terms of the GPLv2
  <http://www.gnu.org/licenses/old-licenses/gpl-2.0.html>, like most MySQL Connectors.
  There are special exceptions to the terms and conditions of the GPLv2 as it is applied to
  this software, see the FLOSS License Exception
  <http://www.mysql.com/about/legal/licensing/foss-exception.html>.

  This program is free software; you can redistribute it and/or modify it under the terms
  of the GNU General Public License as published by the Free Software Foundation; version 2
  of the License.

  This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
  without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  See the GNU General Public License for more details.

  You should have received a copy of the GNU General Public License along with this
  program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth
  Floor, Boston, MA 02110-1301  USA

 */

package demo.fabric;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.Statement;
import java.sql.ResultSet;

import com.mysql.fabric.jdbc.FabricMySQLConnection;

/**
 * Demonstrate working with employee data in MySQL Fabric with Connector/J and the JDBC APIs.
 */
public class EmployeesJdbc {
	public static void main(String args[]) throws Exception {

		String hostname = System.getProperty("com.mysql.fabric.testsuite.hostname");
		String port = System.getProperty("com.mysql.fabric.testsuite.port");
		String database = System.getProperty("com.mysql.fabric.testsuite.database");
		String user = System.getProperty("com.mysql.fabric.testsuite.username");
		String password = System.getProperty("com.mysql.fabric.testsuite.password");

		String baseUrl = "jdbc:mysql:fabric://" + hostname + ":" + Integer.valueOf(port) + "/";

		// Load the driver if running under Java 5
		if (!com.mysql.jdbc.Util.isJdbc4()) {
			Class.forName("com.mysql.fabric.jdbc.FabricMySQLDriver");
		}

		// 1. Create database and table for our demo
		Connection rawConnection = DriverManager.getConnection(
				baseUrl + "mysql?fabricServerGroup=fabric_test1_global",
				user,
				password);
		Statement statement = rawConnection.createStatement();
		statement.executeUpdate("create database if not exists employees");
		statement.close();
		rawConnection.close();

		// We should connect to the global group to run DDL statements,
		// they will be replicated to the server groups for all shards.

		// The 1-st way is to set it's name explicitly via the
		// "fabricServerGroup" connection property
		rawConnection = DriverManager.getConnection(
				baseUrl + database + "?fabricServerGroup=fabric_test1_global",
				user,
				password);
		statement = rawConnection.createStatement();
		statement.executeUpdate("create database if not exists employees");
		statement.close();
		rawConnection.close();

		// The 2-nd way is to get implicitly connected to global group
		// when the shard key isn't provided, ie. set "fabricShardTable"
		// connection property but don't set "fabricShardKey"
		rawConnection = DriverManager.getConnection(
				baseUrl + "employees" + "?fabricShardTable=employees.employees",
				user,
				password);
		// At this point, we have a connection to the global group for 
		// the `employees.employees' shard mapping.
		statement = rawConnection.createStatement();
		statement.executeUpdate("drop table if exists employees");
		statement.executeUpdate("create table employees (emp_no int not null," + 
		          "first_name varchar(50), last_name varchar(50)," +
				  "primary key (emp_no))");

		// 2. Insert data

		// Cast to a Fabric connection to have access to specific methods
		FabricMySQLConnection connection = (FabricMySQLConnection)rawConnection;

		// example data used to create employee records
		Integer ids[] = new Integer[] {1, 2, 10001, 10002};
		String firstNames[] = new String[] {"John", "Jane", "Andy", "Alice"};
		String lastNames[] = new String[] {"Doe", "Doe", "Wiley", "Wein"};

		// insert employee data
		PreparedStatement ps = connection.prepareStatement(
            "INSERT INTO employees.employees VALUES (?,?,?)");
		for (int i = 0; i < 4; ++i) {
			// choose the shard that handles the data we interested in
			connection.setShardKey(ids[i].toString());

			// perform insert in standard fashion
			ps.setInt(1, ids[i]);
			ps.setString(2, firstNames[i]);
			ps.setString(3, lastNames[i]);
			ps.executeUpdate();
		}

		// 3. Query the data from employees
		System.out.println("Querying employees");
		System.out.format("%7s | %-30s | %-30s%n", "emp_no", "first_name", "last_name");
		System.out.println("--------+--------------------------------+-------------------------------");
		ps = connection.prepareStatement(
            "select emp_no, first_name, last_name from employees where emp_no = ?");
		for (int i = 0; i < 4; ++i) {

			// we need to specify the shard key before accessing the data
			connection.setShardKey(ids[i].toString());

			ps.setInt(1, ids[i]);
			ResultSet rs = ps.executeQuery();
			rs.next();
			System.out.format("%7d | %-30s | %-30s%n", rs.getInt(1), rs.getString(2), rs.getString(3));
			rs.close();
		}
		ps.close();

		// 4. Connect to the global group and clean up
		connection.setServerGroupName("fabric_test1_global");
		statement.executeUpdate("drop table if exists employees");
		statement.close();
		connection.close();
	}
}