What would you say about adding `null: false` to these two columns? We don't ever expect them to be empty, do we? (ActiveRecord 3.2 used to create timestamp columns as `NOT NULL`, [but ActiveRecord 4 doesn't](https://stackoverflow.com/questions/20956526/rails-migration-generates-default-timestamps-created-at-updated-at-as-nullabl#answer-20956956).)
```ruby
create_table :groups do |t|
  t.string :name, null: false
  t.timestamps null: false
end
```