default_batch_fetch_size, @BatchSize 가 동작하지 않습니다.

강의 내용 중 N+1, 페이징 등의 복합적인 문제를 해결하기 위해 BatchSize 기능을 이용하는데 해당 기능이 동작하질 않아 질문을 드립니다.

• 스프링부트 설정 파일에 설정한 값은 아래와 같습니다.

# application.yml
spring:
  jpa:
    hibernate:
      ddl-auto: create
      properties:
        hibernate:
          default_batch_fetch_size: 30
          jdbc:
            batch_size: 100

• 강의 예시대로라면 아래와 같이 orderItem을 조회할 때에 IN 조건이 발생되어 총 두 번의 쿼리가 나가야 하지만, 실제로는 IN 조건이 생성되지 않고 BatchSize 설정 전과 같이 여전히 N+1 문제가 해결되지 않는 모습입니다.

2022-11-15 05:11:32.146  INFO 19268 --- [io-49445-exec-5] p6spy                                    : 2022-11-15T05:11:32.146352400 / time:0ms / 
    select
        order0_.order_id as order_id1_10_0_,
        member1_.member_id as member_i1_6_1_,
        delivery2_.delivery_id as delivery1_4_2_,
        order0_.delivery_id as delivery4_10_0_,
        order0_.member_id as member_i5_10_0_,
        order0_.order_date as order_da2_10_0_,
        order0_.status as status3_10_0_,
        member1_.add_time as add_time2_6_1_,
        member1_.city as city3_6_1_,
        member1_.street as street4_6_1_,
        member1_.zipcode as zipcode5_6_1_,
        member1_.description as descript6_6_1_,
        member1_.name as name7_6_1_,
        delivery2_.city as city2_4_2_,
        delivery2_.street as street3_4_2_,
        delivery2_.zipcode as zipcode4_4_2_ 
    from
        orders order0_ 
    inner join
        member member1_ 
            on order0_.member_id=member1_.member_id 
    inner join
        delivery delivery2_ 
            on order0_.delivery_id=delivery2_.delivery_id limit 50 offset 1
2022-11-15 05:11:32.147  INFO 19268 --- [io-49445-exec-5] p6spy                                    : 2022-11-15T05:11:32.147842300 / time:0ms / 
    select
        orderitems0_.order_id as order_id5_9_1_,
        orderitems0_.order_item_id as order_it1_9_1_,
        orderitems0_.order_item_id as order_it1_9_0_,
        orderitems0_.count as count2_9_0_,
        orderitems0_.item_id as item_id4_9_0_,
        orderitems0_.order_id as order_id5_9_0_,
        orderitems0_.order_price as order_pr3_9_0_ 
    from
        order_item orderitems0_ 
    where
        orderitems0_.order_id=11
2022-11-15 05:11:32.148  INFO 19268 --- [io-49445-exec-5] p6spy                                    : 2022-11-15T05:11:32.148833600 / time:0ms / 
    select
        item0_.item_id as item_id2_5_0_,
        item0_.name as name3_5_0_,
        item0_.price as price4_5_0_,
        item0_.stock_quantity as stock_qu5_5_0_,
        item0_1_.author as author1_0_0_,
        item0_1_.isbn as isbn2_0_0_,
        item0_2_.actor as actor1_7_0_,
        item0_2_.director as director2_7_0_,
        item0_3_.artist as artist1_8_0_,
        item0_3_.etc as etc2_8_0_,
        item0_.dtype as dtype1_5_0_ 
    from
        item item0_ 
    left outer join
        book item0_1_ 
            on item0_.item_id=item0_1_.item_id 
    left outer join
        movie item0_2_ 
            on item0_.item_id=item0_2_.item_id 
    left outer join
        music item0_3_ 
            on item0_.item_id=item0_3_.item_id 
    where
        item0_.item_id=9
2022-11-15 05:11:32.149  INFO 19268 --- [io-49445-exec-5] p6spy                                    : 2022-11-15T05:11:32.149825900 / time:0ms / 
    select
        item0_.item_id as item_id2_5_0_,
        item0_.name as name3_5_0_,
        item0_.price as price4_5_0_,
        item0_.stock_quantity as stock_qu5_5_0_,
        item0_1_.author as author1_0_0_,
        item0_1_.isbn as isbn2_0_0_,
        item0_2_.actor as actor1_7_0_,
        item0_2_.director as director2_7_0_,
        item0_3_.artist as artist1_8_0_,
        item0_3_.etc as etc2_8_0_,
        item0_.dtype as dtype1_5_0_ 
    from
        item item0_ 
    left outer join
        book item0_1_ 
            on item0_.item_id=item0_1_.item_id 
    left outer join
        movie item0_2_ 
            on item0_.item_id=item0_2_.item_id 
    left outer join
        music item0_3_ 
            on item0_.item_id=item0_3_.item_id 
    where
        item0_.item_id=10

• 엔티티 클래스의 컬렉션 필드에 @BatchSize를 직접 입력해보았지만 결과는 같았습니다.

• 커뮤니티 질문 중 @Transactional 설정으로 인한 flush 발생 여부에 따라 동작이 상이할 수 있다는 내용을 보고 @Transactional(readonly = true) 설정도 해보았지만 결과는 같았습니다.

전체 프로그램 소스코드 다운로드) https://drive.google.com/file/d/1Q0XQFEBGpAVi0xYhEZgr8qME4rebI39q/view?usp=share_link

spring:
  datasource:
    url: jdbc:h2:tcp://localhost/~/test
    username: sa
    password:
    driver-class-name: org.h2.Driver
  jpa:
    hibernate:
      ddl-auto: create
      properties:
        hibernate:
          default_batch_fetch_size: 30
          jdbc:
            batch_size: 100

spring:
  datasource:
    url: jdbc:h2:tcp://localhost/~/test
    username: sa
    password:
    driver-class-name: org.h2.Driver
  jpa:
    hibernate:
      ddl-auto: create
    properties:
      hibernate:
        default_batch_fetch_size: 30
        jdbc:
          batch_size: 100