Vertica7 Native Connection Load Balance

SELECT SET_LOAD_BALANCE_POLICY(‘ROUNDROBIN‘);

SELECT SET_LOAD_BALANCE_POLICY(‘NONE‘);

SELECT GET_LOAD_BALANCE_POLICY();

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
 
public class VerticaTest {
    private static String USERNAME = "<user>";
    private static String PASSWORD = "<password>";
    private static String URL = "jdbc:vertica://<ip>:5433/<db>";
     
    public static void main(String[] args) throws Exception {
        Class.forName("com.vertica.jdbc.Driver");
        Properties props = new Properties();
        props.put("user", USERNAME);
        props.put("password", PASSWORD);
        props.put("ConnectionLoadBalance", 1);
        for (int x = 1; x <= 10; x++) {
            try {
                Connection conn = DriverManager.getConnection(URL, props);
                Statement stmt = conn.createStatement();
                ResultSet rs = stmt.executeQuery("SELECT node_name FROM v_monitor.current_session;");
                rs.next();
                System.out.println("Connected to node " + rs.getString(1).trim());
                conn.close();
            } catch (SQLException ex) {
                ex.printStackTrace();
            }
        }
    }
}

这里特别注意下面一句，这一句设置了一个连接属性告诉Vertica的JDBC驱动使用负载均衡功能。

props.put("ConnectionLoadBalance", 1);

4. 测试
运行这段代码，可以看到每次连接到的Vertica节点都会按照顺序变动。

另外也可以通过下面的sql来查询当前所有连接的情况。

select node_name, client_hostname from sessions;