Percona Migrations

Allows to use pt-online-schema-change for table changes in MySQL.

Installation

Add this line to your application's Gemfile:

gem 'percona-migrations'

Create config/initializers/percona_migrations.rb with:

PerconaMigrations.database_config = ActiveRecord::Base.configurations.find_db_config(Rails.env)
PerconaMigrations.allow_sql = !Rails.env.production?

ActiveRecord::Migration.send :include, PerconaMigrations::HelperMethods

Usage

class AddAddressToUsers < ActiveRecord::Migration
  def up
    commands = columns.map { |name, type| "ADD COLUMN #{name} #{type}" }

    percona_alter_table :users, commands
  end

  def down
    commands = columns.map { |name, _| "DROP COLUMN #{name}" }

    percona_alter_table :users, commands
  end

  private

  def columns
    { street: 'STRING(255)' },
    { city:   'STRING(255)' },
    { state:  'STRING(2)' },
    { zip:    'STRING(10)' }
  end
end

Configuration

Additional config can optionally be passed either in the initializer or in the migration itself

As a block in the initializer

PerconaMigrations.config do |c|
  c.drop_old_table = false
  c.max_load       = 'Threads_running=60'
end

As a hash argument to the percona_alter_table command

def up
  commands = columns.map { |name, type| "ADD COLUMN #{name} #{type}" }
  options = { drop_old_table: false, max_load: 'Threads_running=60' }

  percona_alter_table :users, commands, options: options
end

Contributing

1. Fork it ( https://github.com/[my-github-username]/percona-migrations/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request