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✨Feat: 인기 전문가 칼럼 조회 Redis 캐시 도입 및 DTO 조회 구조 개선 #23

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Merged
mmije0ng merged 4 commits into from
Jan 8, 2026
Merged

✨Feat: 인기 전문가 칼럼 조회 Redis 캐시 도입 및 DTO 조회 구조 개선 #23

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Feat: 인기 전문가 칼럼 조회 Redis 캐시 및 DTO 조회 구조 개선
mmije0ng Jan 8, 2026
0938457
Refactor: Redis cache 기본 TTL 설정 및 역직렬화 기본 생성자 보완
mmije0ng Jan 8, 2026
c37359a
Refactor: 인기 전문가 칼럼 pinned 여부에 따른 정렬 분기 처리
mmije0ng Jan 8, 2026
225eaad
Refactor: 인기 전문가 칼럼 pinned 정렬 Expression 조건부 생성으로 assert 제거
mmije0ng Jan 8, 2026
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10 changes: 5 additions & 5 deletions README.md
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Expand Up @@ -113,11 +113,11 @@

## 6. 최종 성능 개선 목표 및 달성 현황 요약

| 구분 | 목표치 (Thresholds) | v1 (기존) | v4 (최종) | 결과 |
| :--- | :--- |:----------| :--- | :--- |
| **p(95) Latency** | **2.0s 미만** | 6.71s | **2.56s** | **미달 (CPU 자원 임계)** |
| **p(99) Latency** | **5.0s 미만** | **7.94s** | **3.98s** | **통과** |
| **Error Rate** | **1.0% 미만** | 0.005% | **0.009%** | **통과** |
| 구분 | 목표치 (Thresholds) | v1 (기존) | v4 (최종) | 결과 |
| :--- | :--- |:--------| :--- | :--- |
| **p(95) Latency** | **2.0s 미만** | 6.71s | **2.56s** | **미달 (CPU 자원 임계)** |
| **p(99) Latency** | **5.0s 미만** | 7.94s | **3.98s** | **통과** |
| **Error Rate** | **1.0% 미만** | 0.005% | **0.009%** | **통과** |

**향후 목표**:
로직, 인프라, 캐싱 최적화를 통해 비약적인 성능 향상을 거두었으나, 1,000 VU 환경에서 단일 인스턴스의 CPU 부하로 인해 p(95) 2.0s 목표에는 미달했습니다. 향후 **인스턴스 확장(Scale-out)** 및 **로드밸런서(ALB)** 적용을 통해 자원 부하를 분산하고 최종 목표 지표를 달성할 예정입니다.
15 changes: 10 additions & 5 deletions src/main/java/com/backend/farmon/config/RedisConfig.java
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Expand Up @@ -12,6 +12,8 @@
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.*;

import java.time.Duration;

@Configuration
public class RedisConfig {

Expand Down Expand Up @@ -81,15 +83,18 @@ public RedisTemplate<String, String> autoSearchLogRedisTemplate() {
}

@Bean
public RedisCacheManager redisCacheManager(RedisConnectionFactory redisConnectionFactory) {
RedisCacheConfiguration redisCacheConfiguration = RedisCacheConfiguration.defaultCacheConfig()
.entryTtl(java.time.Duration.ofSeconds(60))
public RedisCacheManager redisCacheManager(RedisConnectionFactory cf) {
RedisCacheConfiguration base = RedisCacheConfiguration.defaultCacheConfig()
.entryTtl(Duration.ofSeconds(60)) // 기본 TTL
.disableCachingNullValues()
.serializeKeysWith(RedisSerializationContext.SerializationPair.fromSerializer(new StringRedisSerializer()))
.serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(new GenericJackson2JsonRedisSerializer()));

return RedisCacheManager.builder(redisConnectionFactory)
.cacheDefaults(redisCacheConfiguration)
RedisCacheConfiguration popularExpert = base.entryTtl(Duration.ofMinutes(5));

return RedisCacheManager.builder(cf)
.cacheDefaults(base)
.withCacheConfiguration("home:popularExpertColumn", popularExpert)
.build();
}
}
30 changes: 11 additions & 19 deletions src/main/java/com/backend/farmon/converter/HomeConverter.java
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Expand Up @@ -6,6 +6,7 @@
import com.backend.farmon.domain.User;
import com.backend.farmon.dto.home.HomePostRow;
import com.backend.farmon.dto.home.HomeResponse;
import com.backend.farmon.dto.home.PopularExpertPostRow;

import java.util.List;
import java.util.Optional;
Expand All @@ -27,33 +28,24 @@ public static HomeResponse.PostListDTO toPostListDTO(List<HomePostRow> rows) {
return new HomeResponse.PostListDTO(list);
}

public static HomeResponse.PopularPostListDTO toPopularPostListDTO(List<Post> postList) {
List<HomeResponse.PopularPostDetailDTO> popularPostDetailDTOList = postList.stream()
.map(HomeConverter::toPopularPostDetailListDTO)
public static HomeResponse.PopularPostListDTO toPopularPostListDTO(List<PopularExpertPostRow> rows) {
List<HomeResponse.PopularPostDetailDTO> popularPostDetailDTOList = rows.stream()
.map(HomeConverter::toPopularPostDetailDTOF)
.toList();

return HomeResponse.PopularPostListDTO.builder()
.popularPostList(popularPostDetailDTOList)
.build();
}

public static HomeResponse.PopularPostDetailDTO toPopularPostDetailListDTO(Post post) {
public static HomeResponse.PopularPostDetailDTO toPopularPostDetailDTOF(PopularExpertPostRow row) {
return HomeResponse.PopularPostDetailDTO.builder()
.popularPostId(post.getId())
.popularPostTitle(post.getPostTitle())
.popularPostContent(post.getPostContent())
.writer(post.getUser().getUserName())
.profileImage(Optional.ofNullable(post.getUser())
.map(User::getExpert)
.map(Expert::getProfileImageUrl)
.orElse(null))
.popularPostImage(
Optional.ofNullable(post.getPostImgs())
.filter(list -> !list.isEmpty()) // 리스트가 비어 있지 않은 경우만 처리
.map(list -> list.get(0)) // 첫 번째 이미지 가져오기
.map(PostImg::getStoredFileName) // 파일명 가져오기
.orElse(null) // 없으면 null 반환
)
.popularPostId(row.getPostId())
.popularPostTitle(row.getTitle())
.popularPostContent(row.getContent())
.writer(row.getWriter())
.profileImage(row.getProfileImageUrl())
.popularPostImage(row.getFirstImageStoredFileName())
.build();
}

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2 changes: 1 addition & 1 deletion src/main/java/com/backend/farmon/dto/home/HomePostRow.java
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Expand Up @@ -10,4 +10,4 @@ public record HomePostRow(
LocalDateTime createdAt,
Long likeCount,
Long commentCount
) {}
) {}
17 changes: 17 additions & 0 deletions src/main/java/com/backend/farmon/dto/home/PopularExpertPostRow.java
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@@ -0,0 +1,17 @@
package com.backend.farmon.dto.home;

import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.NoArgsConstructor;

@Getter
@AllArgsConstructor
@NoArgsConstructor
public class PopularExpertPostRow {
private Long postId;
private String title;
private String content;
private String writer;
private String profileImageUrl;
private String firstImageStoredFileName;
}
Comment on lines +7 to +17
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@coderabbitai coderabbitai bot Jan 8, 2026

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🧹 Nitpick | 🔵 Trivial

캐시 대상 DTO로 적절한 구조입니다.

@NoArgsConstructor(Jackson 역직렬화용)와 @AllArgsConstructor(QueryDSL projection용) 조합이 적절합니다.

불변성을 보장하려면 필드에 final 키워드를 추가하고 @RequiredArgsConstructor 대신 명시적 생성자를 사용하거나, Lombok의 @Value와 @Jacksonized를 조합하는 방안도 고려해 보세요. 현재 구조도 동작에 문제는 없습니다.

🤖 Prompt for AI Agents 
In @src/main/java/com/backend/farmon/dto/home/PopularExpertPostRow.java around
lines 7 - 17, The DTO PopularExpertPostRow should be made immutable: mark all
fields (postId, title, content, writer, profileImageUrl,
firstImageStoredFileName) as final and replace the Lombok constructor
annotations with either (a) an explicit all-args constructor plus a no-args
constructor for Jackson, or (b) use Lombok's @Value combined with @Jacksonized
to get an immutable, Jackson-friendly type; update/remove
@AllArgsConstructor/@NoArgsConstructor and keep the class-level annotations
consistent with your chosen approach (or keep the current combination if you
prefer mutability).

3 changes: 2 additions & 1 deletion src/main/java/com/backend/farmon/repository/PostRepository/PostRepositoryCustom.java
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Expand Up @@ -2,6 +2,7 @@

import com.backend.farmon.domain.Post;
import com.backend.farmon.dto.home.HomePostRow;
import com.backend.farmon.dto.home.PopularExpertPostRow;
import com.backend.farmon.dto.post.PostType;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
Expand All @@ -20,7 +21,7 @@ public interface PostRepositoryCustom {
List<HomePostRow> findTopPostsByPostTypeWithCounts(PostType postType, int limit);

// 인기 전문가 칼럼 6개 조회
List<Post> findTop6ExpertColumnPostsByPostId(List<Long> popularPostsIdList);
List<PopularExpertPostRow> findTopExpertColumnRowsByPopularIds(List<Long> popularPostsIdList, int limit);

// 필터링없이 조회
Page<Post> findAllByBoardId(Long boardId, Pageable pageable);
Expand Down
99 changes: 70 additions & 29 deletions src/main/java/com/backend/farmon/repository/PostRepository/PostRepositoryImpl.java
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Expand Up @@ -4,10 +4,12 @@
import com.backend.farmon.apiPayload.exception.GeneralException;
import com.backend.farmon.domain.*;
import com.backend.farmon.dto.home.HomePostRow;
import com.backend.farmon.dto.home.PopularExpertPostRow;
import com.backend.farmon.dto.post.PostType;
import com.backend.farmon.repository.BoardRepository.BoardRepository;
import com.querydsl.core.BooleanBuilder;
import com.querydsl.core.types.Projections;
import com.querydsl.core.types.dsl.CaseBuilder;
import com.querydsl.core.types.dsl.Expressions;
import com.querydsl.jpa.JPAExpressions;
import com.querydsl.jpa.impl.JPAQueryFactory;
Expand All @@ -20,8 +22,6 @@

import java.util.*;

import static com.backend.farmon.domain.QPostImg.postImg;

@Slf4j
@Repository
@RequiredArgsConstructor
Expand All @@ -33,8 +33,10 @@ public class PostRepositoryImpl implements PostRepositoryCustom {
private final QBoard board = QBoard.board;
private final QPost originalPost = new QPost("originalPost");
private final QComment comment = QComment.comment;

private final QCrop crop = QCrop.crop;
private final QUser user = QUser.user;
private final QExpert expert = QExpert.expert;
private final QPostImg postImg = QPostImg.postImg;

/**
* 공통 select (원본 게시글 기준) + 좋아요/댓글 count를 한 번에 가져오기 위한 프로젝션
Expand Down Expand Up @@ -142,33 +144,72 @@ public List<HomePostRow> findTopPostsByPostTypeWithCounts(PostType postType, int

// 인기 전문가 칼럼 6개 조회
@Override
public List<Post> findTop6ExpertColumnPostsByPostId(List<Long> popularPostsIdList) {
return queryFactory.select(post)
public List<PopularExpertPostRow> findTopExpertColumnRowsByPopularIds(List<Long> popularPostsIdList, int limit) {
QPostImg pi2 = new QPostImg("pi2");

boolean hasPinned = popularPostsIdList != null && !popularPostsIdList.isEmpty();

var query = queryFactory
.select(Projections.constructor(
PopularExpertPostRow.class,
post.id,
post.postTitle,
post.postContent,
user.userName,
expert.profileImageUrl,
postImg.storedFileName
))
.from(post)
.join(post.board, board).fetchJoin()
.leftJoin(post.postlikes, likeCount)
.where(
board.postType.eq(PostType.EXPERT_COLUMN) // 전문가 칼럼 조건
.and(
popularPostsIdList != null && !popularPostsIdList.isEmpty()
? post.id.in(popularPostsIdList).or(post.id.notIn(popularPostsIdList))
: null
)
)
.groupBy(post)
.orderBy(
// 인기 게시글 우선 정렬
popularPostsIdList != null && !popularPostsIdList.isEmpty()
? Expressions.stringTemplate("CASE WHEN {0} IN ({1}) THEN 1 ELSE 2 END", post.id, Expressions.constant(popularPostsIdList)).asc()
: null,
// popularPostsIdList 내부 정렬
popularPostsIdList != null && !popularPostsIdList.isEmpty()
? Expressions.stringTemplate("FIELD({0}, {1})", post.id, Expressions.constant(popularPostsIdList)).asc()
: null,
likeCount.count().desc(), // 좋아요 개수 내림차순
post.createdAt.desc() // 작성일 내림차순
)
.limit(6) // 6개 제한
.join(post.board, board)
.join(post.user, user)
.leftJoin(user.expert, expert)
.leftJoin(likeCount).on(likeCount.post.id.eq(post.id))
// 첫 이미지 1개만 LEFT JOIN
.leftJoin(postImg).on(postImg.id.eq(
JPAExpressions.select(pi2.id.min())
.from(pi2)
.where(pi2.post.id.eq(post.id))
))
.where(board.postType.eq(PostType.EXPERT_COLUMN))
.groupBy(
post.id,
post.postTitle,
post.postContent,
user.userName,
expert.profileImageUrl,
postImg.storedFileName
);

// QueryDSL orderBy에 null 전달 방지 + pinned 조건부 생성
if (hasPinned) {
// pinned 우선 정렬(1) / 나머지(2)
var pinnedFirstOrderExpr = new CaseBuilder()
.when(post.id.in(popularPostsIdList)).then(1)
.otherwise(2);

// pinned 내부 순서 유지 (MySQL: FIELD)
var pinnedInnerOrderExpr = Expressions.numberTemplate(
Integer.class,
"FIELD({0}, {1})",
post.id,
Expressions.constant(popularPostsIdList)
);
Comment on lines +191 to +196
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⚠️ Potential issue | 🟡 Minor

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
# Check for database configurations across the project
echo "=== Database Configuration Files ==="
fd -e properties -e yaml | head -20

echo -e "\n=== Searching for datasource and database configs ==="
rg "spring.datasource|spring.jpa|h2|mysql" -t yaml -t properties -A 2

echo -e "\n=== Checking pom.xml for database dependencies ==="
if [ -f "pom.xml" ]; then
  rg "<artifactId>(h2|mysql|postgresql|mariadb|oracle)" pom.xml
fi

echo -e "\n=== Checking build.gradle for database dependencies ==="
if [ -f "build.gradle" ] || [ -f "build.gradle.kts" ]; then
  rg "(h2|mysql|postgresql|mariadb|oracle)" build.gradle* 2>/dev/null || true
fi

Repository: mmije0ng/FarmON_BE_Refactor

Length of output: 452

🏁 Script executed:

#!/bin/bash
# Search more specifically for application configuration files in src directory
echo "=== Application configuration files in src ==="
find src -name "application*.properties" -o -name "application*.yml" -o -name "application*.yaml" | sort

echo -e "\n=== Content of test application properties ==="
find src -path "*test*" -name "application*.properties" -o -path "*test*" -name "application*.yml" -o -path "*test*" -name "application*.yaml" | xargs cat 2>/dev/null || echo "No test configs found"

echo -e "\n=== Main application configurations ==="
find src/main -name "application*.properties" -o -name "application*.yml" -o -name "application*.yaml" | xargs cat 2>/dev/null || echo "No main configs found"

echo -e "\n=== Checking if PostRepositoryImpl is tested ==="
fd -e java | xargs rg -l "PostRepositoryImpl|PostRepository" | grep -i test

echo -e "\n=== Check build.gradle for test profile ==="
cat build.gradle 2>/dev/null | grep -A 5 -B 5 "test\|h2" || echo "Could not read build.gradle"

Repository: mmije0ng/FarmON_BE_Refactor

Length of output: 2073

🏁 Script executed:

#!/bin/bash
# Look at the PostRepositoryImpl file to understand the context better
echo "=== PostRepositoryImpl.java content around line 191-196 ==="
if [ -f "src/main/java/com/backend/farmon/repository/PostRepository/PostRepositoryImpl.java" ]; then
  cat -n "src/main/java/com/backend/farmon/repository/PostRepository/PostRepositoryImpl.java" | sed -n '180,210p'
else
  echo "File not found, searching for it..."
  find . -name "PostRepositoryImpl.java" -type f
fi

echo -e "\n=== Check if there are test files for PostRepository ==="
find . -path "*test*" -name "*PostRepository*Test*.java" -o -path "*test*" -name "*Post*RepositoryTest.java"

echo -e "\n=== Look for TestApplication or test config ==="
find . -path "*test*" -name "TestApplication.java" -o -path "*test*" -name "Test*.java" | head -10

echo -e "\n=== Check for @DataJpaTest or repository test annotations ==="
rg "@DataJpaTest|@SpringBootTest|testcontainers" -t java | head -20

Repository: mmije0ng/FarmON_BE_Refactor

Length of output: 1640

🏁 Script executed:

#!/bin/bash
# Check if there's a default test configuration when no explicit config exists
echo "=== Check for application.yml or application.properties in test resources ==="
ls -la src/test/resources/ 2>/dev/null || echo "test/resources not found"

echo -e "\n=== Look for spring profiles in test ==="
rg "spring.profiles.active|@ActiveProfiles" -t java

echo -e "\n=== Check FarmonApplicationTests.java ==="
cat -n src/test/java/com/backend/farmon/FarmonApplicationTests.java

echo -e "\n=== Search for any test that calls PostRepository methods ==="
rg -r "getPostsWithPopularByCategory|popularPostsIdList" --type=java src/test/

echo -e "\n=== Check Spring Boot default test database behavior ==="
grep -i "test.database\|datasource.url" src/test/resources/*.properties src/test/resources/*.yml 2>/dev/null || echo "No test datasource config found"

echo -e "\n=== Overall test directory structure ==="
find src/test -type f -name "*.java" -o -name "*.properties" -o -name "*.yml" | head -20

Repository: mmije0ng/FarmON_BE_Refactor

Length of output: 815

MySQL FIELD 함수 사용 - H2 테스트 환경과 호환성 문제

프로젝트의 build.gradle에 H2 데이터베이스가 포함되어 있으며, 테스트 환경에서 명시적인 datasource 설정이 없으므로 @SpringBootTest 실행 시 기본적으로 H2 인메모리 데이터베이스가 사용됩니다. MySQL 전용 함수인 FIELD({0}, {1})은 H2에서 작동하지 않아, 향후 이 코드 경로를 테스트하거나 테스트 범위를 확대할 경우 실패하게 됩니다.

  • 즉시 해결: 줄 190의 주석처럼 MySQL 종속성을 명시적으로 표시하고, 추가로 구현 내용을 명확히 하세요. 
    // MySQL 전용: FIELD 함수로 pinned ID 순서 유지
// H2 테스트 환경에서는 호환되지 않음 (현재 미테스트)
  • 장기 해결: DB 독립성이 필요하다면 QueryDSL의 CaseBuilder를 확장하여 순서를 지정하는 방식으로 대체하세요.
🤖 Prompt for AI Agents 
In
@src/main/java/com/backend/farmon/repository/PostRepository/PostRepositoryImpl.java
around lines 191 - 196, The usage of MySQL-specific FIELD in
pinnedInnerOrderExpr (created via Expressions.numberTemplate in
PostRepositoryImpl) is incompatible with H2 tests; update the code near the
Expressions.numberTemplate call to add the explicit comment lines noting this is
MySQL-only (e.g., "MySQL 전용: FIELD 함수로 pinned ID 순서 유지" and "H2 테스트 환경에서는 호환되지
않음 (현재 미테스트)") so the dependency/limitation is clear, and if DB-independence is
required replace the FIELD-based ordering with a QueryDSL CaseBuilder-based
ordering implementation that reproduces the pinned ID ordering logic.


query.orderBy(
pinnedFirstOrderExpr.asc(),
pinnedInnerOrderExpr.asc(),
likeCount.id.countDistinct().desc(),
post.createdAt.desc()
);
} else {
query.orderBy(
likeCount.id.countDistinct().desc(),
post.createdAt.desc()
);
}

return query
.limit(limit)
.fetch();
}

Expand Down
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