Apache Tajo provides JDBC interface to connect and execute queries. We can use the same JDBC interface to connect Tajo from our Java based application. Let us now understand how to connect Tajo and execute the commands in our sample Java application using JDBC interface in this section.

Download JDBC Driver

Download the JDBC driver by visiting the following link − http://apache.org/dyn/closer.cgi/tajo/tajo-0.11.3/tajo-jdbc-0.11.3.jar.

Now, “tajo-jdbc-0.11.3.jar” file has been downloaded on your machine.

Set Class Path

To make use of the JDBC driver in your program, set the class path as follows −

CLASSPATH = path/to/tajo-jdbc-0.11.3.jar:$CLASSPATH 

Connect to Tajo

Apache Tajo provides a JDBC driver as a single jar file and it is available @ /path/to/tajo/share/jdbc-dist/tajo-jdbc-0.11.3.jar.

The connection string to connect the Apache Tajo is of the following format −

jdbc:tajo://host/
jdbc:tajo://host/database
jdbc:tajo://host:port/  
jdbc:tajo://host:port/database 

Here,

• host − The hostname of the TajoMaster.

• port − The port number that server is listening. Default port number is 26002.

• database − The database name. The default database name is default.

Java Application

Let us now understand Java application.

Coding

import java.sql.*; 
import org.apache.tajo.jdbc.TajoDriver;  

public class TajoJdbcSample {  
   public static void main(String[] args) {  
      Connection connection = null; 
      Statement statement = null;  
      try {
         Class.forName("org.apache.tajo.jdbc.TajoDriver");  
         connection = DriverManager.getConnection(“jdbc:tajo://localhost/default");
         statement = connection.createStatement(); 
         String sql;  
         sql = "select * from mytable”; 
         // fetch records from mytable.  
         ResultSet resultSet = statement.executeQuery(sql);  
         while(resultSet.next()){  
            int id  = resultSet.getInt("id"); 
            String name = resultSet.getString("name");  
            System.out.print("ID: " + id + ";nName: " + name + "n"); 
         }  
         resultSet.close();
         statement.close(); 
         connection.close(); 
      }catch(SQLException sqlException){ 
         sqlException.printStackTrace(); 
      }catch(Exception exception){ 
         exception.printStackTrace(); 
      } 
   } 
}

The application can be compiled and run using the following commands.

Compilation

javac -cp /path/to/tajo-jdbc-0.11.3.jar:. TajoJdbcSample.java 

Execution

java -cp /path/to/tajo-jdbc-0.11.3.jar:. TajoJdbcSample 

Result

The above commands will generate the following result −

ID: 1; 
Name: Adam  

ID: 2; 
Name: Amit  

ID: 3; 
Name: Bob  

ID: 4; 
Name: David  

ID: 5; 
Name: Esha  

ID: 6; 
Name: Ganga 

ID: 7; 
Name: Jack  

ID: 8; 
Name: Leena  

ID: 9; 
Name: Mary  

ID: 10; 
Name: Peter