Using ActiveRecord logger and transaction rollback to review data processing task before going live

data.rake

namespace :data do
  task :console_logger do
    ActiveRecord::Base.logger = Logger.new(STDOUT)
  end

  task :do_some_tweaking, [:user_email, :confirmation] => [:environment, :console_logger] do |t, args|
    User.transaction do
      # ...

      raise "Rolling back after dry run - add CONFIRM to confirm!" unless args[:confirmation] == 'CONFIRM'
    end
  end
end