동시성 문제 - 중복 저장@Componentclass SubscribeWorkbookUseCase( private val subscriptionDao: SubscriptionDao, private val applicationEventPublisher: ApplicationEventPublisher,) { @Transactional fun execute(useCaseIn: SubscribeWorkbookUseCaseIn) { /** 워크북 구독 히스토리를 조회한다. */ val workbookSubscriptionHistory = subscriptionDao.selectTopWorkbookSubscriptionStatus() when { ..
