Redshift is a data warehouse from Amazon that supports SQL. It’s a managed solution on AWS cloud.

We can connect to Redshift database from Java using JDBC and query tables in just like any other database.
I am showing here code that connects to Redshift and queries table schema information.

package com.hadoopnotes;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;

public class RedshiftTest {

	public static void main(String[] args) {

		Connection connection;
		String redshiftUrl = "jdbc:redshift://ip_address:5439/dbatabase";

		try {
			DriverManager.registerDriver(new com.amazon.redshift.jdbc41.Driver());

			Properties driverProperties = new Properties();
			driverProperties.put("user", "myuser");
			driverProperties.put("password", "mypassword");

			connection = DriverManager.getConnection(redshiftUrl, driverProperties);

			String schemaSql = "set search_path to myschema";
			String sql = "select \"column\", type from pg_table_def where schemaname='myschema' and tablename = 'mytable'";

			System.out.println("SQL:" + sql);
			Statement stmt = null;

			try {
				stmt = connection.createStatement();
				stmt.execute(schemaSql);
				System.out.println("Running query now...");
				ResultSet rs = stmt.executeQuery(sql);

				while (rs.next()) {
					// this prints column name and its type
					System.out.println(rs.getString(1) + "--" + rs.getString(2));
				}
			} finally {
				if (stmt != null)
					stmt.close();
			}
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
	}
}

If using Maven to build this Java project, add the following dependency.

<dependency>
     <groupId>com.amazon.redshift</groupId>
     <artifactId>redshift-jdbc41</artifactId>
     <version>1.2.10.1009</version>
</dependency>

Build project and run it.

mvn package
java -cp target/myjar.jar com.hadoopnotes.RedshiftTest

Or, from command line, compile and run:

javac -cp redshift-jdbc41-1.2.10.1009.jar com/hadoopnotes/RedshiftTest.java
java -cp .:redshift-jdbc41-1.2.10.1009.jar com.hadoopnotes.RedshiftTest