This gem is a DuckDB database adapter for ActiveRecord.

Activerecord::Duckdb providers DuckDB database access for Ruby on Rails applications.

~ NOTE: This gem is still a work in progress, so it might not work exactly as expected just yet. Some ActiveRecord features haven’t been added and/or fully tested.

This gem relies on the ruby-duckdb ruby gem as its database adapter. Thus it provides a seamless integration with the DuckDB database.

Both gems requires that you have duckdb. DuckDB has many installation options available that can be found on their installation page.

# OSx
brew install duckdb

# Most Linux distributions
curl https://install.duckdb.org | sh

Install the gem and add to the application's Gemfile by executing:

bundle add "activerecord-duckdb"

If bundler is not being used to manage dependencies, install the gem by executing:

gem install activerecord-duckdb

Adjust your database.yml file to use the duckdb adapter.

development:
  adapter: duckdb
  database: db/development.duckdb

test:
  adapter: duckdb
  database: db/test.duckdb

production:
  adapter: duckdb
  database: db/production.duckdb

Run some migrations to ensure the database is ready.

rails g model Notice name:string email:string content:string

Notice.create(name: 'John Doe', email: '[email protected]', content: 'Something happened at work today!')
Notice.find_by(email: '[email protected]')
Notice.all
Notice.last.delete

~ At the moment using an in-memory database is very limited and still in development. NOTE: When using a memory database, any transactional operations will be lost when the process exits. The only reason I can think of is that you might want to use an in-memory database for testing purposes, data analysis, or some sort of quick calculations where the data is not critical.

temporary_database:
  adapter: duckdb
  database: :memory

class User < ApplicationRecord
  establish_connection(:temporary_database)
end

Of you can set your own database configuration in the config/database.yml file. When using temporary databases you'll also have to generate your own schema on the fly rather than migrations creating them automatically.

test:
  adapter: duckdb
  database: :memory

production:
  adapter: duckdb
  database: :memory

The adapter supports advanced configuration options for extensions, settings, secrets, and database attachments. These are configured in your database.yml file.

Install and load DuckDB extensions automatically on connection:

development:
  adapter: duckdb
  database: db/development.duckdb
  extensions:
    - httpfs
    - postgres_scanner
    - parquet

Configure DuckDB settings. The adapter applies secure defaults which you can override:

development:
  adapter: duckdb
  database: db/development.duckdb
  settings:
    threads: 4
    memory_limit: '2GB'
    max_temp_directory_size: '8GB'

Default Settings:

Notes:

• allow_persistent_secrets and allow_community_extensions are applied before loading extensions
• lock_configuration = true is automatically applied at the end to lock all settings

Configure secrets for accessing external services (S3, PostgreSQL, etc.). Two styles are supported:

Style 1: Unnamed secrets (key is the secret type):

development:
  adapter: duckdb
  database: ducklake
  secrets:
    postgres:
      host: localhost
      database: mydb
      user: admin
      password: secret
    s3:
      key_id: AKIAIOSFODNN7EXAMPLE
      secret: wJalrXUtnFEMI/K7MDENG
      region: us-east-1

Style 2: Named secrets (explicit type key, hash key becomes secret name):

development:
  adapter: duckdb
  database: ducklake
  secrets:
    my_prod_bucket:
      type: s3
      key_id: AKIAIOSFODNN7EXAMPLE
      secret: wJalrXUtnFEMI/K7MDENG
      region: us-east-1
      scope: 's3://prod-bucket'
    my_dev_bucket:
      type: s3
      key_id: AKIAIOSFODNN7EXAMPLE2
      secret: anotherSecretKey
      region: us-west-2
      scope: 's3://dev-bucket'

Named secrets allow multiple secrets of the same type with different scopes.

Attach external databases (PostgreSQL, MySQL, DuckLake, etc.):

development:
  adapter: duckdb
  database: ducklake
  extensions:
    - postgres_scanner
    - ducklake
  secrets:
    postgres:
      host: localhost
      database: mydb
      user: admin
      password: secret
  attachments:
    - name: pg_db
      connection_string: 'postgres:'
      type: POSTGRES
    - name: ducklake
      connection_string: 'ducklake:postgres:'
      options: "DATA_PATH 's3://my-bucket', ENCRYPTED"

If you need to switch to a specific attached database after configuration, you can use the use_database option:

development:
  adapter: duckdb
  database: db/development.duckdb
  attachments:
    - name: analytics
      connection_string: 's3://bucket/analytics.duckdb'
  use_database: analytics  # Switch to the attached database

The following steps are required to setup a sample application using the activerecord-duckdb gem:

1. Create a new Rails application:

rails new sample_app --database=sqlite3

2. Add the activerecord-duckdb gem to your Gemfile:

gem 'activerecord-duckdb'

3. Run bundle install to install the gem.

4. Update the config/database.yml file to use the duckdb adapter:

development:
  adapter: duckdb
  database: db/development.db

test:
  adapter: duckdb
  database: :memory

production:
  adapter: duckdb
  database: :memory

5. Generate a model for the sample application:

rails g model User name:string email:string

5. Run some migrations to ensure the database is ready:

rails db:create; rails db:migrate

6. Create some sample data:

User.create(name: 'John Doe', email: '[email protected]')
User.create(name: 'Jane Doe', email: '[email protected]')

7. Run some queries:

User.all
User.find_by(email: '[email protected]')
User.last.delete

Bug reports and pull requests are welcome on GitHub at https://github.com/tarellel/activerecord-duckdb.

The gem is available as open source under the terms of the MIT License.