ActiveRecord JDBC Adapter

Gem Version

ActiveRecord-JDBC-Adapter (AR-JDBC) is a database adapter for Rails' ActiveRecord component that can be used with JRuby. It allows use of virtually any JDBC-compliant database with your JRuby on Rails application.

We supports ActiveRecord 2.3, 3.x and 4.x from a single code base. You'll need JRuby >= 1.6.8 (we recommend using the latest and greatest of JRubies) thus Java >= 1.6 is mandatory.

AR-JDBC 1.3.x is a recommended update for all 1.2.x users.

Our latest major version 1.3.x represents a few months of refactoring and updates covering (not just) new/old ActiveRecord features. It tries to stay compatible with 1.2.9 as much as possible but please be aware that it's not always possible(mostly for the best), please read our migration guide for details.


ActiveRecord-JDBC-Adapter provides full or nearly full support for: MySQL, PostgreSQL, SQLite3, Oracle, MS-SQL* (SQL Server), DB2, Firebird, Derby, HSQLDB, H2, and Informix.

Other databases will require testing and likely a custom configuration module. Please join the JRuby mailing list to help us discover support for more databases.

Using ActiveRecord JDBC

Inside Rails

To use AR-JDBC with JRuby on Rails:

  1. Choose the adapter you wish to gem install. The following pre-packaged adapters are available:
  • Base JDBC (activerecord-jdbc-adapter) - supports all available databases via JDBC, but requires you to download and manually setup a JDBC driver for the database you're using
  • MySQL (activerecord-jdbcmysql-adapter)
  • PostgreSQL (activerecord-jdbcpostgresql-adapter)
  • SQLite3 (activerecord-jdbcsqlite3-adapter)
  • Derby (activerecord-jdbcderby-adapter)
  • HSQLDB (activerecord-jdbchsqldb-adapter)
  • H2 (activerecord-jdbch2-adapter)
  • MSSQL (activerecord-jdbcmssql-adapter) - uses the OSS jTDS driver by default which might have issues with the latest SQLServer (but should work using the Microsoft JDBC Driver for SQL Server - we recommend using 4.0)

2a. If you're generating a new Rails application, use the following command:

jruby -S rails new sweetapp

2b. Otherwise, you might need to perform some extra configuration steps to prepare your Rails application for JDBC.

You'll need to modify your Gemfile to use the activerecord-jdbc-adapter gem (or one of the helper gems) under JRuby. Change your Gemfile to look something like the following:

gem 'mysql2', platform: :ruby
gem 'activerecord-jdbcmysql-adapter', platform: :jruby

If you're (stuck) using Rails 2.3, you might need to:

jruby script/generate jdbc
  1. Configure your database.yml in the normal Rails style:
  adapter: mysql2 # or mysql
  database: blog_development
  username: blog
  password: 1234

Legacy Configuration: If you use one of the activerecord-jdbcxxx-adapter gems, you can still put a 'jdbc' prefix in front of the database adapter name, e.g. adapter: jdbcmysql.

For plain JDBC database configurations, you'll need to know the database driver class and URL (do not forget to put the driver .jar(s) on the class-path) e.g.:

  adapter: jdbc
  username: blog
  password: 1234
  driver: com.mysql.jdbc.Driver
  url: jdbc:mysql://localhost:3306/blog_development

For JNDI data sources, you may simply specify the JNDI location as follows, it's recommended to use the same adapter: setting as one would configure when using "bare" (JDBC) connections e.g. :

  adapter: postgresql
  jndi: jdbc/PostgreDS

NOTE: any other settings such as database:, username:, properties: make no difference since everything is already configured on the JNDI DataSource end.

JDBC driver specific properties might be set if you use an URL to specify the DB or preferably using the properties: syntax:

  adapter: mysql
  username: blog
  password: blog
  url: "jdbc:mysql://localhost:3306/blog?profileSQL=true"
  properties: # specific to com.mysql.jdbc.Driver
    socketTimeout:  60000
    connectTimeout: 60000

If you're really old school you might want to use AR-JDBC with a DB2 on z/OS:

  adapter: jdbc
  url: jdbc:db2j:net://mightyzoshost:446/RAILS_DBT1
  schema: DB2XB12
  database: RAILS_DB1
  tablespace: TSDE911
    first_table: TSDE912
  username: business
  password: machines
  encoding: unicode
  # you can force a (DB2) dialect using:
  #dialect: as400

More information on (configuring) AR-JDBC might be found on our wiki.

Standalone with ActiveRecord

Once the setup is made (see below) you can establish a JDBC connection like this (e.g. for activerecord-jdbcderby-adapter):

  adapter: 'derby',
  database: 'db/my-database'

or using (requires that you manually put the driver jar on the class-path):

  :adapter => 'jdbc',
  :driver => 'org.apache.derby.jdbc.EmbeddedDriver',
  :url => 'jdbc:derby:sample_db;create=true'

Using Bundler

Proceed as with Rails; specify ActiveRecord in your Bundle along with the chosen JDBC adapter(s), this time sample Gemfile for MySQL:

gem 'activerecord', '~> 3.2.14'
gem 'activerecord-jdbcmysql-adapter', :platform => :jruby

When you require 'bundler/setup' everything will be set up for you as expected.

You do not need to use the 'helper' activerecord-jdbcxxx-adapter gem we provide but than should make sure an appropriate JDBC driver is available at runtime, in that case simply setup your Gemfile as:

gem 'activerecord', '~> 4.0.0'
gem 'activerecord-jdbc-adapter', '~> 1.3.2', platform: :jruby

Without Bundler

Install the needed gems with JRuby, for example:

gem install activerecord -v "~> 3.2.10"
gem install activerecord-jdbc-adapter --ignore-dependencies

If you wish to use the adapter for a specific database, you can install it directly and the (jdbc-) driver gem (dependency) will be installed as well:

jruby -S gem install activerecord-jdbcderby-adapter

Your program should include:

require 'active_record'
require 'activerecord-jdbc-adapter' if defined? JRUBY_VERSION
# or in case you're using the pre-packaged adapter gem :
require 'activerecord-jdbcderby-adapter' if defined? JRUBY_VERSION

Extending AR-JDBC

You can create your own extension to AR-JDBC for a JDBC-based database that core AR-JDBC does not support. We've created an example project for the Intersystems Cache database that you can examine as a template. See the cachedb-adapter project for more information.


The source for activerecord-jdbc-adapter is available using git:

git clone git://

Please note that the project manages multiple gems from a single repository, if you're using Bundler >= 1.2 it should be able to locate all gemspecs from the git repository. Sample Gemfile for running with (MySQL) master:

gem 'activerecord-jdbc-adapter', :github => 'jruby/activerecord-jdbc-adapter'
gem 'activerecord-jdbcmysql-adapter', :github => 'jruby/activerecord-jdbc-adapter'

Getting Involved

Please read our CONTRIBUTING & RUNNING_TESTS guides for starters. You can always help us by maintaining AR-JDBC's wiki.


Please report bugs at our issue tracker. If you're not sure if something's a bug, feel free to pre-report it on the mailing lists or ask on the #JRuby IRC channel on (try web-chat).


This project was originally written by Nick Sieger and Ola Bini with lots of help from the JRuby community. Polished 3.x compatibility and 4.x support (for AR-JDBC >= 1.3.0) was managed by Karol Bucek among others.


ActiveRecord-JDBC-Adapter is open-source released under the BSD/MIT license. See LICENSE.txt included with the distribution for details.

Open-source driver gems within AR-JDBC's sources are licensed under the same license the database's drivers are licensed. See each driver gem's LICENSE.txt.