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[BE] refactor: 특정 상품에 대한 리뷰 목록 조회 N+1 문제 완전히 해결 #838

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[BE] refactor: 특정 상품에 대한 리뷰 목록 조회 N+1 문제 완전히 해결 #838

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f370b08
feat: 리뷰 목록 조회에서 태그 정보를 가져올 때 발생하는 N+1 문제 해결
70825 Oct 27, 2023
9e5494a
refactor: 테스트 코드 로그 제거
70825 Oct 27, 2023
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19 changes: 16 additions & 3 deletions backend/src/main/java/com/funeat/review/application/ReviewService.java
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Original file line number Diff line number Diff line change
Expand Up @@ -38,8 +38,10 @@
import com.funeat.review.specification.SortingReviewSpecification;
import com.funeat.tag.domain.Tag;
import com.funeat.tag.persistence.TagRepository;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.Objects;
import java.util.Optional;
import java.util.stream.Collectors;
import org.springframework.context.ApplicationEventPublisher;
Expand Down Expand Up @@ -184,10 +186,21 @@ private List<SortingReviewDto> getSortingReviews(final Member member, final Prod

private List<SortingReviewDto> addTagsToSortingReviews(
final List<SortingReviewDtoWithoutTag> sortingReviewDtoWithoutTags) {
return sortingReviewDtoWithoutTags.stream()
.map(reviewDto -> SortingReviewDto.toDto(reviewDto,
tagRepository.findTagsByReviewId(reviewDto.getId())))
final List<Long> reviewIds = sortingReviewDtoWithoutTags.stream()
.map(SortingReviewDtoWithoutTag::getId)
.collect(Collectors.toList());
final List<ReviewTag> reviewTags = reviewTagRepository.findReviewTagByReviewIds(reviewIds);

final List<SortingReviewDto> sortingReviewDtos = new ArrayList<>();
for (final SortingReviewDtoWithoutTag sortingReviewDtoWithoutTag : sortingReviewDtoWithoutTags) {
final List<Tag> tags = reviewTags.stream()
.filter(reviewTag -> Objects.equals(sortingReviewDtoWithoutTag.getId(), reviewTag.getReview().getId()))
.map(ReviewTag::getTag)
.collect(Collectors.toList());
final SortingReviewDto sortingReviewDto = SortingReviewDto.toDto(sortingReviewDtoWithoutTag, tags);
sortingReviewDtos.add(sortingReviewDto);
}
return sortingReviewDtos;
Comment on lines +194 to +203
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다른 효율적인 방법은 없을까요?
조회된 reviewTag 를 sortingReviewDtoWithoutTags 만큼 계속 돌 거 같아서요!! ㅎㅎ

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이게 ReviewTag를 통해 Review와 Tag를 서로 찾아 조립해주는 역할을 하는거라 저는 여기까지가 한계... ㅠㅠ
제가 보기엔 쿼리문을 덜 날리는 대신 메모리에서 더 처리하기 vs 쿼리문을 더 날려서 메모리에서 덜 처리하기라 저는 전자를 택했어요

전자) O(Review 수 * ReviewTag 수)로 메모리에서 처리하는 대신 쿼리문 14개에서 3개로 줄이기 (= 현재 PR 코드)
후자) O(Review 수)로 메모리는 덜 쓰고, 각 리뷰가 원하는 태그들을 쿼리문으로 날려서 디비에서 가져오기 (= 현재 프로덕션 코드)

}

private Specification<Review> getSortingSpecification(final Product product, final String sortOption,
Expand Down
8 changes: 8 additions & 0 deletions backend/src/main/java/com/funeat/review/persistence/ReviewTagRepository.java
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
import org.springframework.data.domain.Pageable;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;

public interface ReviewTagRepository extends JpaRepository<ReviewTag, Long> {

Expand All @@ -21,4 +22,11 @@ public interface ReviewTagRepository extends JpaRepository<ReviewTag, Long> {
void deleteByReview(final Review review);

List<ReviewTag> findByReview(final Review review);

@Query("SELECT rt "
+ "FROM ReviewTag rt "
+ "JOIN FETCH rt.review "
+ "JOIN FETCH rt.tag "
+ "WHERE rt.review.id IN :reviewIds")
List<ReviewTag> findReviewTagByReviewIds(@Param("reviewIds") final List<Long> reviewIds);
}
6 changes: 3 additions & 3 deletions backend/src/test/java/com/funeat/acceptance/review/ReviewSteps.java
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Original file line number Diff line number Diff line change
Expand Up @@ -61,10 +61,10 @@ public class ReviewSteps {
.cookie("SESSION", loginCookie)
.queryParam("sort", sort)
.queryParam("page", page)
.queryParam("lastReviewId", lastReviewId).log().all()
.queryParam("lastReviewId", lastReviewId)
.when()
.get("/api/products/{product_id}/reviews", productId)
.then().log().all()
.then()
.extract();
}

Expand All @@ -80,7 +80,7 @@ public class ReviewSteps {
return given()
.when()
.get("/api/ranks/products/{product_id}/reviews", productId)
.then().log().all()
.then()
.extract();
}

Expand Down