Setting up the JDBC Driver

This section describes the steps you need to take before you can write or run programs that use the JDBC interface.

Precompiled versions of the driver can be downloaded from the PostgreSQL JDBC web site.

Alternatively you can build the driver from source, but you should only need to do this if you are making changes to the source code. To build the JDBC driver, you need gradle and a JDK (currently at least jdk1.8).

If you have several Java compilers installed, maven will use the first one on the path. To use a different one set JAVA_HOME to the Java version you wish to use. For example, to use a different JDK than the default, this may work:

 JAVA_HOME=/usr/local/jdk1.8.0_45

To compile the driver simply run gradlew assemble or gradlew build if you want to run the tests in the top level directory.

If you want to skip test execution, add the option -DskipTests. The compiled driver will be placed in pgjdbc/build/libs/postgresql-MM.nn.pp.jar

Where MM is the major version, nn is the minor version and pp is the patch version. Versions for JDBC3 and lower can be found here

This is a very brief outline of how to build the driver. Much more detailed information can be found on the github repo

Even though the JDBC driver should be built with Gradle, for situations, where use of Gradle is not possible, e.g., when building pgJDBC for distributions, the pgJDBC Gradle build provides a convenience source release artifact *-src.tar.gz - a Maven based project. The Maven based project contains a version of the JDBC driver with complete functionality, which can be used in production and is still validly buildable within the Maven build environment. The Maven-based project is created with gradlew -d :postgresql:sourceDistribution -Prelease. The produced *-src.tar.gz can be then found in pgjdbc/build/distributions/ directory. JDBC driver can be built from the Maven-based project with mvn package or, when the tests are to be skipped, with mvn -DskipTests package. Source files *-src.tar.gz’s are released in the Maven central repository.

To use the driver, the JAR archive named postgresql-MM.nn.pp.jar needs to be included in the class path, either by putting it in the CLASSPATH environment variable, or by using flags on the java command line.

For instance, assume we have an application that uses the JDBC driver to access a database, and that application is installed as /usr/local/lib/myapp.jar . The PostgreSQL JDBC driver installed as /usr/local/pgsql/share/java/postgresql-MM.nn.pp.jar . To run the application, we would use:

export CLASSPATH=/usr/local/lib/myapp.jar:/usr/local/pgsql/share/java/postgresql-42.5.0.jar:. java MyApp

Current Java applications will likely use maven, gradle or some other package manager. Use this to search for the latest jars and how to include them in your project

Loading the driver from within the application is covered in Initializing the Driver.

Out of the box, Java does not support unix sockets so the PostgreSQL server must be configured to allow TCP/IP connections. Starting with server version 8.0 TCP/IP connections are allowed from localhost . To allow connections to other interfaces than the loopback interface, you must modify the postgresql.conf file’s listen_addresses setting.

Once you have made sure the server is correctly listening for TCP/IP connections the next step is to verify that users are allowed to connect to the server. Client authentication is setup in pg_hba.conf . Refer to the main PostgreSQL documentation for details .

When creating a database to be accessed via JDBC it is important to select an appropriate encoding for your data. Many other client interfaces do not care what data you send back and forth, and will allow you to do inappropriate things, but Java makes sure that your data is correctly encoded. Do not use a database that uses the SQL_ASCII encoding. This is not a real encoding and you will have problems the moment you store data in it that does not fit in the seven bit ASCII character set. If you do not know what your encoding will be or are otherwise unsure about what you will be storing the UNICODE encoding is a reasonable default to use.