[week 04/김준영] 영속성 컨텍스트 #33
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junyoungkim12
requested review from
ByeongJun-Jang,
SJ70,
WhitebearM,
changkiyun,
hanni66 and
ulthwjdwkd
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hanni66
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Apr 26, 2024
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저도 궁금했던 지점들을 잘 설명해주신 것 같아요~!
수고 많으셨습니다~!😉
week04/영속성 컨텍스트.md
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혹시 영속성 컨텍스트의 지연 로딩 기능은 어떤 역할을 하나요?
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JPA에서는 데이터를 조회할 때 즉시 로딩(EAGER)과 지연 로딩(LAZY) 두 가지 방식이 있는데,
즉시 로딩은 데이터를 조회할 때 연관된 데이터까지 한 번에 불러오는 것이고,
지연 로딩은 필요한 시점에 연관된 데이터를 불러오는 것 입니다.
만약 Member 엔티티와 Team 엔티티가 N:1 매핑으로 관계를 맺고 있을 때
즉시 로딩으로 Member를 조회하면 연관된 Team의 수 만큼 Join되어 쿼리가 나가게 됩니다.
그 결과 조회 쿼리 하나가 아닌 많은 쿼리문을 수행하게 되어 성능이 저하됩니다.
그러나 지연 로딩을 사용하면 Member만 조회할 수 있어서 많은 쿼리문을 실행하지 않을 수 있기 때문에
필요한 객체의 데이터만 불러올 수 있는 장점이 있다고 합니다!
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