ActiveRecordの after_xxx系コールバックは return falseしても ROLLBACKしてくれない

Module: ActiveRecord::Callbacks

If a before_* callback cancels the action a ROLLBACK is issued. You can also trigger a ROLLBACK raising an exception in any of the callbacks, including after_* hooks. Note, however, that in that case the client needs to be aware of it because an ordinary save will raise such exception instead of quietly returning false.

例外投げればROLLBACKしてくれる
.