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Tools to help with managing database operations with Sequel through Rake tasks


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SequelTools brings some tooling around Sequel migrations and database management, providing tasks to create, drop and migrate the database, plus dumping and restoring from the last migrated schema. It can also display which migrations are applied and which ones are missing. It's highly customizable and supports multiple databases or environments. It integrates well with Rake as well.

Currently only PostgreSQL is supported out-of-the-box for some tasks, but it should allow you to specify the database vendor specific commands to support your vendor of choice without requiring changes to SequelTools itself. Other vendors can be supported through additional gems or you may want to submit pull requests for your preferred DB vendor if you prefer so that it would be supported out-of-the-box by this gem.

The idea behind SequelTools is to create a collection of supported actions, which depend on the database adapter/vendor. Those supported actions can then be translated to Rake tasks as a possible interface.


Add this line to your application's Gemfile:

gem 'sequel_tools'
gem 'rake'

# For PostgreSQL:
gem 'pg', platform: :mri
gem 'jdbc-postgres', platform: :jruby

And then execute:



Here's a sample Rakefile supporting migrate actions:

require 'bundler/setup'
require 'sequel_tools'

base_config = {
  # project_root: Dir.pwd,
  dbadapter: 'postgres',
  dbname: 'mydb',
  username: 'myuser',
  password: 'secret',
  # default log_level is nil, in which mode the executed actions such as
  # starting/finishing a migration in a given direction or creating and
  # dropping the database are not logged to standard output.
  log_level: :info,

  # Default options:
  sql_log_level: :debug,
  dump_schema_on_migrate: false, # it's a good idea to enable it for the reference environment
  pg_dump: 'pg_dump', # command used to run pg_dump
  pg_dump: 'psql', # command used to run psql when calling rake db:shell if adapter is postgres
  migrations_location: 'db/migrations',
  schema_location: 'db/migrations/schema.sql',
  seeds_location: 'db/seeds.rb',
  # for tasks such as creating the database:
  # when nil, defaults to the value of the :dbadapter config.
  # This is the database we should connect to before executing "create database dbname"
  maintenancedb: :default,
  # migrations_table: 'schema_migrations',
  # allow other tables data to be included in the dump file generated by rake db:schema_dump
  # extra_tables_in_dump: nil
  # for example, if you want to keep migrations from ActiveRecord in the dump file, while using
  # another table for Sequel migrations:
  # migrations_table: 'sequel_schema_migrations',
  # extra_tables_in_dump: ['schema_migrations'],

namespace 'db' do
  SequelTools.inject_rake_tasks base_config.merge(dump_schema_on_migrate: true), self

namespace 'dbtest' do
  SequelTools.inject_rake_tasks base_config.merge(dbname: 'mydb_test'), self

Then you are able to run several tasks (rake -T will list all supported):

rake db:create
rake db:new_migration[migration_name]
rake db:migrate
# setup creates the database, loads the latest schema
# and import seeds when available
rake dbtest:setup
# reset drops (if existing) then recreate the database, run all migrations
# and import seeds when available
rake dbtest:reset
# shell opens a psql section to the database for the PostgreSQL adapter
rake db:shell
# irb runs "bundle exec sequel" pointing to the database and stores the connection in "DB"
rake db:irb
rake db:rollback
rake db:status
# version displays latest applied migration
rake db:version
rake db:seed
rake db:redo[migration_filename]
rake db:down[migration_filename]
rake db:up[migration_filename]
# schema_dump is called automatically after migrate/rollback/up/down/redo
# if passing { dump_schema_on_migrate: true } to the config
rake db:schema_dump
# database must be empty before calling db:schema_load
rake db:schema_load

You may define your own command to open a shell to your database upon the 'db:shell' task. PostgreSQL is supported out-of-the-box, but if it wasn't, here's a sample script that would get the job done:


# name it like ~/bin/opensql for example and give it execution permission


Then you may set shell_command: '~/bin/opensql' in config.

Alternatively you can define the shell_#{dbadapter} action if you prefer. Take a look at the implementation for shell_postgres to see how to do that. If you want to share that action with others you may either submit a pull request to this project or create a separate gem to add support for your database to sequel_tools, which wouldn't require waiting for me to approve your pull requests and you'd be able to maintain it independently.

Development and running tests

The tests assume the database sequel_tools_test_pw exists and can be only accessed using a username and password. It also assumes a valid user/passwd is sequel_tools_user/secret. The database sequel_tools_test is also required to exist and it should be possible to access it using the trust authentication method, without requiring a password. You may achieve that by adding these lines to the start of your pg_hba.conf:

host sequel_tools_test_pw   all md5
host sequel_tools_test      all trust

Then feel free to run the tests:

bundle exec rspec

The default strategy is a safe one, which uses Open3.capture3 to actually run bundle exec rake ... whenever we want to test the Rake integration and we do that many times in the tests. Running bundle exec is slow, so it adds a lot to the test suite total execution time. Alternatively, although less robust, you may run the tests using a fork-rake approach, which avoids calling bundle exec each time we want to run a Rake task. Just define the FORK_RAKE environment variable:

FORK_RAKE=1 bundle exec rspec

In my environment this would complete the full suite in about half the time.


Bug reports and pull requests are welcome on GitHub at


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


Tools to help with managing database operations with Sequel through Rake tasks







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