Transactional Patterns

Basic Rules

• @Transactional belongs on service methods, never controllers or repositories
• Default propagation is REQUIRED — joins existing transaction or creates one
• Always use on methods that write to the DB or coordinate multiple writes
• @Transactional(readOnly = true) on all read-only service methods — enables optimizations

@Service
@RequiredArgsConstructor
@Transactional(readOnly = true) // default for all methods in this service
public class OrderService {