[JPA] OneToOne 양방향 매핑과 LazyLoading

OneToOne 양방향 매핑할 때 주의할 점이 Lazy Loading이 안되는 문제이다.

출처

호오 정말 그럴까? 실험 !!

상황

@Entity
public class Instagram {
    @OneToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "PLACE_ID")
    public Place place;
    ...
}

@Entity
public class Place {
    @OneToOne(fetch = FetchType.LAZY, mappedBy = "place")
    public Instagram instagram;
    ...
}

주인: Instagram, OneToOne 양방향 매핑을 해준 상태

주인이 부를 때에는 Lazy Loading이 동작한다.

    @Test
    void test() {
        Place place = placeRepository.save(new Place());
        Instagram instagram = instagramRepository.save(Instagram.builder().place(place).build());

        Instagram savedInstagram = instagramRepository.findById(1L).get();
    }

Hibernate: 
    select
        instagram0_.instagram_id as instagra1_4_0_,
        instagram0_.created_date as created_2_4_0_,
        instagram0_.modified_date as modified3_4_0_,
        instagram0_.hashtag_count as hashtag_4_4_0_,
        instagram0_.hashtag_name as hashtag_5_4_0_,
        instagram0_.place_id as place_id6_4_0_ 
    from
        instagram instagram0_ 
    where
        instagram0_.instagram_id=?

place id만 불러온다
Lazy Loading 잘 되쥬?

주인이 아닌 쪽에서 부를 때는 Lazy Loading이 동작하지 않는다.

이번에는 주인이 아닌 쪽을 조회해보자.

    @Test
    void test() {
        Place place = placeRepository.save(new Place());
        Instagram instagram = instagramRepository.save(Instagram.builder().place(place).build());

        Place savedPlace = placeRepository.findById(1L).get();
    }

Hibernate: 
    select
        place0_.place_id as place_id1_8_0_,
        place0_.created_date as created_2_8_0_,
        place0_.modified_date as modified3_8_0_,
        place0_.category as category4_8_0_,
        place0_.kakao_id as kakao_id5_8_0_,
        place0_.latitude as latitude6_8_0_,
        place0_.longitude as longitud7_8_0_,
        place0_.road_address_name as road_add8_8_0_,
        place0_.place_name as place_na9_8_0_,
        place0_.place_url as place_u10_8_0_ 
    from
        place place0_ 
    where
        place0_.place_id=?
Hibernate: 
    select
        instagram0_.instagram_id as instagra1_4_0_,
        instagram0_.created_date as created_2_4_0_,
        instagram0_.modified_date as modified3_4_0_,
        instagram0_.hashtag_count as hashtag_4_4_0_,
        instagram0_.hashtag_name as hashtag_5_4_0_,
        instagram0_.place_id as place_id6_4_0_ 
    from
        instagram instagram0_ 
    where
        instagram0_.place_id=?

주인이 아닌 쪽에 fetchType을 Lazy로 했음에도 불구하고 EagerLoading으로 조회한다.
주인이 아닌 Place는 Instagram에 대한 fk가 없기 때문에 나중에 Lazy Loading할 수 없어서 바로 불러버리는 둡