I don't like to use @Transactional in methods I like to keep it more micro level

[livid sonnet]

For the context

what do you think of this?

    @Transactional
    public Customer updateCustomer(Long id, CustomerDTO customerDTO) {
        log.info("Updating customer with ID: {}", id);
        Customer existingCustomer = customerRepository.findById(id)
                .orElseThrow(() -> new ResourceNotFoundException("Customer not found with ID: " + id));

        modelMapper.map(customerDTO, existingCustomer);
        existingCustomer.setCustomerId(id);

        List<LocationDTO> pickupLocationDTOs= customerDTO.getPickupLocations();
        List<LocationDTO> deliveryLocationDTOs = customerDTO.getDeliveryLocations();

        List<Location> pickupLocations = mapLocations(pickupLocationDTOs, LocationType.PICKUP, existingCustomer);
        List<Location> deliveryLocations = mapLocations(deliveryLocationDTOs, LocationType.DELIVERY, existingCustomer);

        List<Location> allLocations = new ArrayList<>(pickupLocations.size()+deliveryLocations.size());
        allLocations.addAll(pickupLocations);
        allLocations.addAll(deliveryLocations);
        locationRepository.saveAll(allLocations);
        return customerRepository.save(existingCustomer);
    }

[formal moon]

<@&987246399047479336> please have a look, thanks.

[hollow jungle]

Putting a transactional annotation on a method like this is actually a perfect use case

[livid sonnet]

but again, what if there's a lot of transactions?

this is just 2 transactions.

[hollow jungle]

I only see a single transaction?

[livid sonnet]

yeah only one trnasaction. what I meant is what if multiple db entry calls

[hollow jungle]

your db can run multiple transactions in parallel as long as you're modifying different rows etc 🙂

DBs are awesome

[frail shadow]

Indeed, and we do this at considerable scale. There are a few levers you can pull on a method to indicate whether it needs a transaction, whether it will modify data or could use a readonly transaction, and how it should act if entered without a transaction or in one (creating a new transaction, joining the existing transaction and whether it can elevate a readonly transaction to modify data).

The transaction isolation can be specified to get dirrty-reads, consistent reads or fully serialised transactions (and other nuanced options besides).

Transactions are a fundamental part of concurrent database access.

[safe moth]

that's usually the case where you want to use it

transactional, in simplest terms, means "do everything or nothing"

if you only have 1 db call, you can omit it, but then you need to be careful with fetching entity relationships because their getters might perform a DB call if they're not fetched already

outside of an active transaction that will result in an exception, and even with it, it is uusally better to fetch everying in one DB round trip