Using JDBC to access Greenplum

The JDBC is the driver used to access a database with Java. Greenplum has a full working JDBC implementation.

In that short article we'll have a.

# # Download and install

It is possible to download the JDBC for Greenplum directly from the Greenplum Community Edition site (http://www.greenplum . com/community/downloads/database-ce/).

Look for the * "Connectivity Tools" * file.

You'll receive a link to download the archive file.

Extract the archive and run the binary extracted. Then Follow the instructions on screens and in less than a minute you have installed JDBC.

# # Prepare The Greenplum server

After a successful installation, make sure this server accepts TCP connections from the desired hosts. Check that *listen_addresses* are properly set in postgresql.conf.

**note:** by default and Greenplum listens to any address.

Another aspect you have to consider are the user authentication, which is delegated to the pg_hba.conf file (please refer T o page of Greenplum adminguide for more information).

After you have verified the "user is able" to "the" database, you can go on and test JDBC.

Connecting to a Greenplum Database and JDBC is a three steps procedure:

* Import JDBC

* Load the driver

* Connect to the database

Remember that the *forname* function can throw a *classnotfoundexception* if the driver are not available. We don't try to catch this exception in the simple example below. You are should in your production environment.

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To connect to a database using JDBC, you have to use a connection URL. It can be in one of these three forms:

* Jdbc:postgresql:databasename

* Jdbc:postgresql://host/databasename

* Jdbc:postgresql://host:port/databasename

Build a URL that is suits your needs and use it with the getconnection function. For example:

Package com.gp.dbtest;

Import java.sql.Connection;

Import Java.sql.DriverManager;

Import Java.sql.ResultSet;

Import java.sql.SQLException;

Import java.sql.Statement;

public class Gpdbtest {

public static void Main (string[] args) {

try {

Class.forName ("Org.postgresql.Driver");

Connection db = Drivermanager.getconnection ("jdbc:postgresql://192.168.1.23:5432/zwcdb", "ZHONGWC", "ZHONGWC");

Statement st = Db.createstatement ();

ResultSet rs = st.executequery ("SELECT * from TAB_GP limit 1 offset 0");

while (Rs.next ()) {

System.out.println (rs.getstring (1));

}

Rs.close ();

St.close ();

catch (ClassNotFoundException e) {

E.printstacktrace ();

catch (SQLException e) {

E.printstacktrace ();

}

}

}

Author: csdn Blog Zhongweicheng