A code example referenced in our blog post: https://medium.com/expected-behavior/our-plan-for-zero-downtime-database-transitions-with-rails-part-2-3cc4c5d6051c

ex03-happy-path-destination-model.rb

module ActiveMigrator
  class ActiveMigratorDestinationModel < ActiveRecord::Base
    self.abstract_class = true
    # disable STI for this "copy" model
    self.inheritance_column = :_type_disabled
    establish_connection DB_ACTIVE_MIGRATOR_CONFIGURATION[:destination]
  end
end
module ActiveMigrator
  module ActiveMigratorSource
    extend ActiveSupport::Concern
    included do
      @active_migrator_destination_klass_name = "ActiveMigrator::#{self.name}ActiveMigratorDestinationModel"
      eval <<-STR, nil, __FILE__, __LINE__
        ActiveMigrator.send(:remove_const, :#{self.name}ActiveMigratorDestinationModel) if defined?(#{@active_migrator_destination_klass_name})
        class #{@active_migrator_destination_klass_name} < ActiveMigrator::ActiveMigratorDestinationModel
          self.table_name = '#{table_name}'
          self.record_timestamps = false
          self.lock_optimistically = false
        end
      STR
    end
  end
end