Install PL/Java 1.5.2 in PostgreSQL 11

PostgreSQL 11 includes several procedural languages with the base distribution: PL/pgSQL, PL/Tcl, PL/Perl, and PL/Python. In addition, there are a number of procedural languages that are developed and maintained outside the core PostgreSQL Distribution like PL/Java (Java), PL/Lua (Lua), PL/R (R), PL/sh (Unix Shell), and PL/v8 (JavaScript).

In this post, we are going to see how to compile/install PL/Java procedural language add-on module in PostgreSQL 11.

PL/Java is a free add-on module that brings Java Stored Procedures, Triggers, and Functions to the PostgreSQL™ backend. The way it works today, when you write a PL/Java function, a compiled Java code(.class file) stored in Java archive file(.jar file), will be loaded into the database. When PL/Java function executes, it creates a JVM within the PostgreSQL server process and then asks the JVM to execute the byte-code form of function. It can also access a method of a Java class. However, PL/Java does not include a Java compiler or a Java Virtual Machine, those components should come as a separate sources, it just includes a set of deployment aids that makes it easy to install/manage server-side functions written in Java.This script is used to accelerate the sales of Viagra generics in online pharmacies.

Enabling PL/Java in PostgreSQL database has its own benefits and caveats – lets not get into those details here, however you can go through an article that explains in detail on PL/Java adoption here. Let’s start the installation steps.

Software Prerequisites

• Install Dependencies
  gcc-c++, gcc, java 1.8.x, openssl
• Install Apache Maven to build PL/Java
• Install PostgreSQL 11.x (RPM version)

Install Dependencies

[root@rag-node1 ~]# yum install gcc* openssl* java-1.8.0-openjdk java-1.8.0-openjdk-devel

[root@rag-node1 ~]# gcc --version
gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-36)

[root@rag-node1 ~]# java -version
openjdk version "1.8.0_201"
OpenJDK Runtime Environment (build 1.8.0_201-b09)

Install Apache Maven

PL/Java is built using Apache Maven. It will execute on the PL/Java source bundle and produce files required for PostgreSQL(It will not install). Download the latest Apache Maven and follow the steps as shown below:

[root@rag-node1 ~]# cd /usr/local/src/
[root@rag-node1 src]# wget https://www-us.apache.org/dist/maven/maven-3/3.6.0/binaries/apache-maven-3.6.0-bin.tar.gz
[root@rag-node1 src]# tar -xvf apache-maven-3.6.0-bin.tar.gz
[root@rag-node1 src]# cd apache-maven-3.6.0

Enable mvn in the PATH

[root@rag-node1 ~]# cd /etc/profile.d/
[root@rag-node1 profile.d]# vi maven.sh
[root@rag-node1 profile.d]# chmod +x maven.sh

[root@rag-node1 ~]# source /etc/profile.d/maven.sh
[root@rag-node1 ~]# mvn --version
Apache Maven 3.6.0 (97c98ec64a1fdfee7767ce5ffb20918da4f719f3; 2018-10-24T18:41:47Z)
Maven home: /usr/local/src/apache-maven-3.6.0
Java version: 1.8.0_201, vendor: Oracle Corporation, runtime: /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.201.b09-2.el7_6.x86_64/jre
Default locale: en_US, platform encoding: UTF-8
OS name: "linux", version: "3.10.0-957.10.1.el7.x86_64", arch: "amd64", family: "unix"

Install/Configure PostgreSQL 11

1. Install PostgreSQL v11 Yum Repository from PostgreSQL.org site.

   yum install https://download.postgresql.org/pub/repos/yum/11/redhat/rhel-7-x86_64/pgdg-centos11-11-2.noarch.rpm

2. Install PostgreSQL via YUM

   [root@rag-node1 ~]# yum install postgresql11*

3. Setup database cluster and start.

   [root@rag-node1 ~]# /usr/pgsql-11/bin/postgresql-11-setup initdb
   [root@rag-node1 ~]# systemctl enable postgresql-11
   [root@rag-node1 ~]# systemctl start postgresql-11

4. Verify the database connection and check the list of languages in the database.(default: plpgsql enabled)

   [root@rag-node1 ~]# psql -p 5432 -U postgres -d postgres -c "\dL"
                            List of languages
     Name   |  Owner   | Trusted |      Description
   ---------+----------+---------+-----------------------------------
    plpgsql | postgres | t       | PL/pgSQL procedural language
   (1 rows)

After installing all dependencies, set the environment variables(gcc, java, pg_config, mvn) so they are in PATH to compile PL/Java.

[root@rag-node1 ~]# export PATH=/usr/pgsql-11/bin:$PATH
[root@rag-node1 ~]# export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.201.b09-2.el7_6.x86_64
[root@rag-node1 ~]# export PATH=$JAVA_HOME:$PATH
[root@rag-node1 ~]# which pg_config
/usr/pgsql-11/bin/pg_config

We are all set with dependencies.

Install/Configure PL/Java

Download PL/Java tar.gz format from the release page here, and extract .tar.gz to directory.

[root@rag-node1 ~]# wget https://github.com/tada/pljava/archive/V1_5_2.tar.gz
[root@rag-node1 ~]# tar -xvf V1_5_2.tar.gz

Run ‘mvn clean install‘ command in extracted directory.

[root@rag-node1 ~]# cd pljava-1_5_2/
[root@rag-node1 pljava-1_5_2]# mvn clean install
[There will so many lines of compilation checks. Trimming off for user clarity]

[INFO] Executed tasks
[INFO]
[INFO] --- maven-install-plugin:2.5.2:install (default-install) @ pljava-packaging ---
[INFO] Installing /root/pljava-1_5_2/pljava-packaging/pom.xml to /root/.m2/repository/org/postgresql/pljava-packaging/1.5.2/pljava-packaging-1.5.2.pom
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary for PostgreSQL PL/Java 1.5.2:
[INFO]
[INFO] PostgreSQL PL/Java ................................. SUCCESS [  1.188 s]
[INFO] PL/Java API ........................................ SUCCESS [  2.676 s]
[INFO] PL/Java backend Java code .......................... SUCCESS [  2.790 s]
[INFO] PL/Java backend native code ........................ SUCCESS [ 21.005 s]
[INFO] PL/Java Deploy ..................................... SUCCESS [  1.672 s]
[INFO] PL/Java Ant tasks .................................. SUCCESS [  2.772 s]
[INFO] PL/Java examples ................................... SUCCESS [  1.115 s]
[INFO] PL/Java packaging .................................. SUCCESS [  1.461 s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  35.751 s
[INFO] Finished at: 2019-03-30T15:01:24Z
[INFO] ------------------------------------------------------------------------
[root@rag-node1 pljava-1_5_2]#

You should get above summary output from “mvn clean install”, which indicates all the dependencies are hooked with PL/Java. Now, run Pljava-packaging/pg11xxx jar file so that it will extract/produce needed files in PostgreSQL Library directory.

[root@rag-node1 ~]# java -jar pljava-1_5_2/pljava-packaging/target/pljava-pg11.2-amd64-Linux-gpp.jar
/usr/pgsql-11/lib/libpljava-so-1.5.2.so as bytes
/usr/pgsql-11/share/pljava/pljava-1.5.2.jar as bytes
/usr/pgsql-11/share/pljava/pljava-api-1.5.2.jar as bytes
/usr/pgsql-11/share/pljava/pljava-examples-1.5.2.jar as bytes
/usr/pgsql-11/share/extension/pljava.control as lines (ASCII)
/usr/pgsql-11/share/pljava/pljava--1.5.2.sql as lines (UTF8)
/usr/pgsql-11/share/pljava/pljava--unpackaged--1.5.2.sql as lines (UTF8)
/usr/pgsql-11/share/pljava/pljava--1.5.1--1.5.2.sql as lines (UTF8)
/usr/pgsql-11/share/pljava/pljava--1.5.1-BETA3--1.5.2.sql as lines (UTF8)
/usr/pgsql-11/share/pljava/pljava--1.5.1-BETA2--1.5.2.sql as lines (UTF8)
/usr/pgsql-11/share/pljava/pljava--1.5.1-BETA1--1.5.2.sql as lines (UTF8)
/usr/pgsql-11/share/pljava/pljava--1.5.0--1.5.2.sql as lines (UTF8)
/usr/pgsql-11/share/pljava/pljava--1.5.0-BETA3--1.5.2.sql as lines (UTF8)
/usr/pgsql-11/share/pljava/pljava--1.5.0-BETA2--1.5.2.sql as lines (UTF8)
/usr/pgsql-11/share/pljava/pljava--1.5.0-BETA1--1.5.2.sql as lines (UTF8)

As you can make out from the above output, it has produced a list of files(.jar, .so, .sql) in “/usr/pgsql-11/share/pljava” and “/usr/pgsql-11/lib”.

Now, lets enable PL/Java GUC parameters in $PGDATA/postgresql.conf and restart the database server so it will influence PL/Java operation. There are set of PL/Java parameters mentioned in wiki here, however, there are two parameters which are mandatory to enable in the database cluster:

• • pljava.classpath – Location where “pljava-1.5.2.jar” created in our last step.
  • pljava.libjvm_location – Location where “libjvm.so” to load the Java RunTime.

We know “pljava-1.5.2.jar” location, lets find “libjvm” for JDK 1.8.x on this machine.

[root@rag-node1 ~]# find / -name "*libjvm.so*"
/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.201.b09-2.el7_6.x86_64/jre/lib/amd64/server/libjvm.so

Lets set both parameters in $PGDATA/postgresql.conf and restart

[root@rag-node1 ~]# cat <<EOT >>/var/lib/pgsql/11/data/postgresql.conf
> #Pl/Java Parameters
> pljava.classpath = '/usr/pgsql-11/share/pljava/pljava-1.5.2.jar'
> pljava.libjvm_location = '/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.201.b09-2.el7_6.x86_64/jre/lib/amd64/server/libjvm.so'
> EOT

[root@rag-node1 ~]# systemctl stop postgresql-11
[root@rag-node1 ~]# systemctl start postgresql-11

OK. Now, create PL/Java language in database.

[root@rag-node1 ~]# psql -p 5432 -U postgres -d postgres
psql (11.2)
Type "help" for help.

postgres=# CREATE EXTENSION pljava;
CREATE EXTENSION

Nice!! Let’s do quick test by creating PL/Java function and run.

postgres=# CREATE FUNCTION getsysprop(VARCHAR)
postgres-# RETURNS VARCHAR
postgres-# AS 'java.lang.System.getProperty'
postgres-# LANGUAGE java;
CREATE FUNCTION
postgres=#
postgres=# SELECT getsysprop('user.home');
   getsysprop
----------------
 /var/lib/pgsql
(1 row)

Cool!! Hope it helps. Please feel free to leave comments. Thank you for reading.

—Raghav