Spring Boot's Open Session in View Silently Causes Hidden Database Query Problems

Spring Boot enables the Open Session in View (OSIV) pattern by default, keeping the JPA persistence context open for the entire duration of an HTTP request. This allows lazy-loaded relationships to resolve even outside service-layer transactions, such as during DTO mapping or JSON serialization in the controller layer. While this prevents LazyInitializationException errors and makes applications appear to work correctly, it can silently trigger unintended database queries far outside the intended persistence boundary. The hidden behavior often goes unnoticed until endpoints become slow or monitoring tools reveal unexpected SQL queries being executed after service methods have returned. Developers are advised to explicitly disable OSIV via spring.jpa.open-in-view=false and instead design APIs that load all required data within transactional boundaries.