Optimizing Performance

server:
  http2.enabled: true
  ssl.enabled: true     # HTTP/2 requires TLS in browsers
  port: 8443

server:
  compression:
    enabled: true
    mime-types: application/json,application/xml,text/html,text/css,text/plain
    min-response-size: 1024

@Query("SELECT o FROM Order o JOIN FETCH o.items WHERE o.userId = :uid")
List<Order> findOrdersWithItems(@Param("uid") Long uid);

@Entity
@Table(name = "orders", indexes = {
  @Index(name = "idx_orders_user_status", columnList = "user_id, status"),
  @Index(name = "idx_orders_created", columnList = "created_at")
})
public class Order { /* … */ }

@Cacheable(value = "users", key = "#id")
public UserDto get(Long id) { return repo.findById(id).map(UserDto::from).orElseThrow(); }
// Hibernate L2: spring.jpa.properties.hibernate.cache.use_second_level_cache=true

@EntityGraph(attributePaths = {"items", "customer"})
@Query("SELECT o FROM Order o WHERE o.id = :id")
Optional<Order> findFullOrder(@Param("id") Long id);

@GetMapping("/orders")
public Page<OrderDto> list(@PageableDefault(size = 50, sort = "createdAt,desc") Pageable p) {
  return repo.findAll(p).map(OrderDto::from);
}