@Transactional does not work on private methods or same-class calls

@Transactional is implemented via AOP proxy. If you call a @Transactional method from another method in the same class (self-invocation), or annotate a private method, the proxy is bypassed and no transaction is started.

Move the transactional logic to a separate Spring-managed bean, or inject a self-reference (less elegant):

// BAD — self-invocation bypasses proxy
@Service
public class OrderService {
    public void processOrders() {
        saveOrder(); // no transaction started
    }

    @Transactional
    public void saveOrder() { ... }
}

// GOOD — separate bean
@Service
public class OrderService {
    private final OrderWriter writer;

    public void processOrders() {
        writer.saveOrder(); // proxy is invoked
    }
}

@Service
public class OrderWriter {
    @Transactional
    public void saveOrder() { ... }
}

Spring creates a CGLIB or JDK proxy around the bean. Calls from outside the bean go through the proxy and trigger advice (transactions). Internal calls use this directly, skipping the proxy entirely.