⚡️ [Improve] 페이징 정렬 기능 개선 및 querydsl 적용

backend-board/build.gradle

@@ -49,6 +49,12 @@ dependencies {
     implementation 'io.jsonwebtoken:jjwt-api:0.12.3'
     implementation 'io.jsonwebtoken:jjwt-impl:0.12.3'
     implementation 'io.jsonwebtoken:jjwt-jackson:0.12.3'
+
+    //Querydsl 추가
+    implementation 'com.querydsl:querydsl-jpa:5.0.0:jakarta'
+    annotationProcessor "com.querydsl:querydsl-apt:${dependencyManagement.importedProperties['querydsl.version']}:jakarta"
+    annotationProcessor "jakarta.annotation:jakarta.annotation-api"
+    annotationProcessor "jakarta.persistence:jakarta.persistence-api"
 }
 
 tasks.named('test') {
@@ -62,3 +68,8 @@ test {
 jar {
     enabled = false
 }
+
+clean {
+    delete file('src/main/generated')
+}
+

backend-board/src/main/java/com/backendboard/domain/comment/dto/CommentReadResponse.java

@@ -3,6 +3,7 @@
 import java.time.LocalDateTime;
 
 import com.backendboard.domain.comment.entity.Comment;
+import com.querydsl.core.annotations.QueryProjection;
 
 import io.swagger.v3.oas.annotations.media.Schema;
 import lombok.Builder;
@@ -30,9 +31,9 @@ public class CommentReadResponse {
 	private final LocalDateTime lastModifiedDate;
 
 	@Builder
-	private CommentReadResponse(Long id, Long postId, String author, String content, LocalDateTime createdDate,
-		LocalDateTime lastModifiedDate
-	) {
+	@QueryProjection
+	public CommentReadResponse(Long id, Long postId, String author, String content, LocalDateTime createdDate,
+		LocalDateTime lastModifiedDate) {
 		this.id = id;
 		this.postId = postId;
 		this.author = author;

backend-board/src/main/java/com/backendboard/domain/comment/dto/CommentSliceResponse.java

@@ -3,6 +3,7 @@
 import java.time.LocalDateTime;
 
 import com.backendboard.domain.comment.entity.Comment;
+import com.querydsl.core.annotations.QueryProjection;
 
 import io.swagger.v3.oas.annotations.media.Schema;
 import lombok.Builder;
@@ -30,7 +31,8 @@ public class CommentSliceResponse {
 	private final LocalDateTime lastModifiedDate;
 
 	@Builder
-	private CommentSliceResponse(Long id, Long postId, String author, String content, LocalDateTime createdDate,
+	@QueryProjection
+	public CommentSliceResponse(Long id, Long postId, String author, String content, LocalDateTime createdDate,
 		LocalDateTime lastModifiedDate) {
 		this.id = id;
 		this.postId = postId;

backend-board/src/main/java/com/backendboard/domain/comment/entity/Comment.java

@@ -7,6 +7,8 @@
 import jakarta.persistence.GeneratedValue;
 import jakarta.persistence.GenerationType;
 import jakarta.persistence.Id;
+import jakarta.persistence.Index;
+import jakarta.persistence.Table;
 import lombok.AccessLevel;
 import lombok.Builder;
 import lombok.Getter;
@@ -15,6 +17,11 @@
 @Entity
 @Getter
 @NoArgsConstructor(access = AccessLevel.PROTECTED)
+@Table(
+	indexes = {
+		@Index(name = "idx_created_date", columnList = "createdDate")
+	}
+)
 public class Comment extends BaseEntity {
 	@Id
 	@GeneratedValue(strategy = GenerationType.IDENTITY)

backend-board/src/main/java/com/backendboard/domain/comment/repository/CommentQueryRepository.java

@@ -0,0 +1,103 @@
+package com.backendboard.domain.comment.repository;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.springframework.data.domain.Pageable;
+import org.springframework.data.domain.Slice;
+import org.springframework.data.domain.SliceImpl;
+import org.springframework.data.domain.Sort;
+import org.springframework.stereotype.Repository;
+
+import com.backendboard.domain.comment.dto.CommentReadResponse;
+import com.backendboard.domain.comment.dto.CommentSliceResponse;
+import com.backendboard.domain.comment.dto.QCommentReadResponse;
+import com.backendboard.domain.comment.dto.QCommentSliceResponse;
+import com.backendboard.domain.comment.entity.QComment;
+import com.backendboard.domain.user.entity.QUser;
+import com.backendboard.global.error.CustomError;
+import com.backendboard.global.error.CustomException;
+import com.querydsl.core.types.Order;
+import com.querydsl.core.types.OrderSpecifier;
+import com.querydsl.core.types.dsl.PathBuilder;
+import com.querydsl.jpa.impl.JPAQueryFactory;
+
+import lombok.RequiredArgsConstructor;
+
+@Repository
+@RequiredArgsConstructor
+public class CommentQueryRepository {
+	private final JPAQueryFactory queryFactory;
+
+	public CommentReadResponse findCommentReadResponse(Long commentId) {
+		QComment comment = QComment.comment;
+		QUser user = QUser.user;
+
+		CommentReadResponse result = queryFactory
+			.select(new QCommentReadResponse(
+				comment.id,
+				comment.postId,
+				user.nickname,
+				comment.content,
+				comment.createdDate,
+				comment.lastModifiedDate
+			))
+			.from(comment)
+			.join(user).on(comment.userId.eq(user.id))
+			.where(comment.id.eq(commentId))
+			.fetchOne();
+
+		if (result == null) {
+			throw new CustomException(CustomError.COMMENT_NOT_FOUND);
+		}
+
+		return result;
+	}
+
+	public Slice<CommentSliceResponse> findCommentSliceResponse(Long postId, boolean deleted, Pageable pageable) {
+		QComment comment = QComment.comment;
+		QUser user = QUser.user;
+		boolean hasNext = false;
+		List<OrderSpecifier<?>> orderSpecifiers = getOrderSpecifiers(pageable, comment);
+
+		List<CommentSliceResponse> content = queryFactory
+			.select(new QCommentSliceResponse(
+				comment.id,
+				comment.postId,
+				user.nickname,
+				comment.content,
+				comment.createdDate,
+				comment.lastModifiedDate
+			))
+			.from(comment)
+			.join(user).on(comment.userId.eq(user.id))
+			.where(
+				comment.postId.eq(postId),
+				comment.deleted.eq(deleted)
+			)
+			.orderBy(orderSpecifiers.toArray(new OrderSpecifier[0]))
+			.offset(pageable.getOffset())
+			.limit(pageable.getPageSize() + 1)
+			.fetch();
+
+		if (content.size() > pageable.getPageSize()) {
+			content.remove(pageable.getPageSize());
+			hasNext = true;
+		}
+
+		return new SliceImpl<>(content, pageable, hasNext);
+	}
+
+	private List<OrderSpecifier<?>> getOrderSpecifiers(Pageable pageable, QComment comment) {
+		List<OrderSpecifier<?>> orders = new ArrayList<>();
+
+		for (Sort.Order order : pageable.getSort()) {
+			PathBuilder<?> entityPath = new PathBuilder<>(comment.getType(), comment.getMetadata());
+			orders.add(
+				new OrderSpecifier(order.isAscending() ? Order.ASC : Order.DESC, entityPath.get(order.getProperty()))
+			);
+		}
+		return orders;
+	}
+
+}

backend-board/src/main/java/com/backendboard/domain/comment/service/CommentServiceImpl.java

@@ -1,10 +1,5 @@
 package com.backendboard.domain.comment.service;
 
-import java.util.Map;
-import java.util.Set;
-import java.util.function.Function;
-import java.util.stream.Collectors;
-
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.domain.Slice;
 import org.springframework.stereotype.Service;
@@ -17,6 +12,7 @@
 import com.backendboard.domain.comment.dto.CommentUpdateRequest;
 import com.backendboard.domain.comment.dto.CommentUpdateResponse;
 import com.backendboard.domain.comment.entity.Comment;
+import com.backendboard.domain.comment.repository.CommentQueryRepository;
 import com.backendboard.domain.comment.repository.CommentRepository;
 import com.backendboard.domain.user.entity.User;
 import com.backendboard.domain.user.repository.UserRepository;
@@ -29,6 +25,7 @@
 @Service
 @RequiredArgsConstructor
 public class CommentServiceImpl implements CommentService {
+	private final CommentQueryRepository commentQueryRepository;
 	private final CommentRepository commentRepository;
 	private final UserRepository userRepository;
 
@@ -56,11 +53,7 @@ public CommentUpdateResponse updateComment(CommentUpdateRequest request, Long co
 
 	@Override
 	public CommentReadResponse getComment(Long commentId) {
-		Comment comment = commentRepository.findById(commentId)
-			.orElseThrow(() -> new CustomException(CustomError.COMMENT_NOT_FOUND));
-		User author = userRepository.findById(comment.getUserId())
-			.orElseThrow(() -> new CustomException(CustomError.USER_NOT_FOUND));
-		return CommentReadResponse.toDto(comment, author.getNickname());
+		return commentQueryRepository.findCommentReadResponse(commentId);
 	}
 
 	@Transactional
@@ -77,17 +70,7 @@ public void deleteComment(Long commentId, Long authUserId) {
 
 	@Override
 	public Slice<CommentSliceResponse> getCommetsSlice(Long postId, Pageable pageable) {
-		Slice<Comment> comments = commentRepository.findByPostIdAndDeleted(postId, false, pageable);
-
-		Set<Long> userIds = comments.stream().map(Comment::getUserId).collect(Collectors.toSet());
-
-		Map<Long, User> userMap = userRepository.findAllById(userIds)
-			.stream().collect(Collectors.toMap(User::getId, Function.identity()));
-
-		return comments.map(comment -> {
-			User user = userMap.get(comment.getUserId());
-			return CommentSliceResponse.toDto(comment, user.getNickname());
-		});
+		return commentQueryRepository.findCommentSliceResponse(postId, false, pageable);
 	}
 
 	public void validateAuthor(Comment comment, User user) {

backend-board/src/main/java/com/backendboard/domain/post/dto/PostReadResponse.java

@@ -56,15 +56,14 @@ private PostReadResponse(Long id, String author, String title, String content, L
 	}
 
 	@Builder
-
-	public static PostReadResponse toDto(Post post, String author, List<PostImage> images, Long viewCount) {
+	public static PostReadResponse toDto(Post post, String author, List<PostImage> images) {
 		return PostReadResponse.builder()
 			.id(post.getId())
 			.author(author)
 			.title(post.getTitle())
 			.content(post.getContent())
 			.likeCount(post.getLikeCount())
-			.viewCount(viewCount)
+			.viewCount(post.getViewCount())
 			.images(images.stream().map(PostImageReadResponse::toDto).toList())
 			.createdDate(post.getCreatedDate())
 			.lastModifiedDate(post.getLastModifiedDate())

backend-board/src/main/java/com/backendboard/domain/post/dto/PostSliceResponse.java

@@ -3,6 +3,7 @@
 import java.time.LocalDateTime;
 
 import com.backendboard.domain.post.entity.Post;
+import com.querydsl.core.annotations.QueryProjection;
 
 import io.swagger.v3.oas.annotations.media.Schema;
 import lombok.Builder;
@@ -36,7 +37,8 @@ public class PostSliceResponse {
 	private final LocalDateTime lastModifiedDate;
 
 	@Builder
-	private PostSliceResponse(Long id, String author, String title, String content, Long likeCount, Long viewCount,
+	@QueryProjection
+	public PostSliceResponse(Long id, String author, String title, String content, Long likeCount, Long viewCount,
 		LocalDateTime createdDate, LocalDateTime lastModifiedDate) {
 		this.id = id;
 		this.author = author;

backend-board/src/main/java/com/backendboard/domain/post/entity/Post.java

@@ -7,7 +7,9 @@
 import jakarta.persistence.GeneratedValue;
 import jakarta.persistence.GenerationType;
 import jakarta.persistence.Id;
+import jakarta.persistence.Index;
 import jakarta.persistence.Lob;
+import jakarta.persistence.Table;
 import lombok.AccessLevel;
 import lombok.Builder;
 import lombok.Getter;
@@ -16,6 +18,13 @@
 @Entity
 @Getter
 @NoArgsConstructor(access = AccessLevel.PROTECTED)
+@Table(
+	indexes = {
+		@Index(name = "idx_like_count", columnList = "likeCount"),
+		@Index(name = "idx_view_count", columnList = "viewCount"),
+		@Index(name = "idx_created_date", columnList = "createdDate")
+	}
+)
 public class Post extends BaseEntity {
 	@Id
 	@GeneratedValue(strategy = GenerationType.IDENTITY)

backend-board/src/main/java/com/backendboard/domain/post/respository/PostQueryRepository.java

@@ -0,0 +1,71 @@
+package com.backendboard.domain.post.respository;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.springframework.data.domain.Pageable;
+import org.springframework.data.domain.Slice;
+import org.springframework.data.domain.SliceImpl;
+import org.springframework.data.domain.Sort;
+import org.springframework.stereotype.Repository;
+
+import com.backendboard.domain.post.dto.PostSliceResponse;
+import com.backendboard.domain.post.dto.QPostSliceResponse;
+import com.backendboard.domain.post.entity.QPost;
+import com.backendboard.domain.user.entity.QUser;
+import com.querydsl.core.types.Order;
+import com.querydsl.core.types.OrderSpecifier;
+import com.querydsl.core.types.dsl.PathBuilder;
+import com.querydsl.jpa.impl.JPAQueryFactory;
+
+import lombok.RequiredArgsConstructor;
+
+@Repository
+@RequiredArgsConstructor
+public class PostQueryRepository {
+	private final JPAQueryFactory queryFactory;
+
+	public Slice<PostSliceResponse> findPostSliceResponse(boolean deleted, Pageable pageable) {
+		QPost post = QPost.post;
+		QUser user = QUser.user;
+		boolean hasNext = false;
+		List<OrderSpecifier<?>> orderSpecifiers = getOrderSpecifiers(pageable, post);
+
+		List<PostSliceResponse> content = queryFactory
+			.select(new QPostSliceResponse(
+				post.id,
+				user.nickname,
+				post.title,
+				post.content,
+				post.likeCount,
+				post.viewCount,
+				post.createdDate,
+				post.lastModifiedDate
+			))
+			.from(post)
+			.join(user).on(post.userId.eq(user.id))
+			.where(post.deleted.eq(deleted))
+			.orderBy(orderSpecifiers.toArray(new OrderSpecifier[0]))
+			.offset(pageable.getOffset())
+			.limit(pageable.getPageSize() + 1)
+			.fetch();
+
+		if (content.size() > pageable.getPageSize()) {
+			content.remove(pageable.getPageSize());
+			hasNext = true;
+		}
+		return new SliceImpl<>(content, pageable, hasNext);
+	}
+
+	private List<OrderSpecifier<?>> getOrderSpecifiers(Pageable pageable, QPost post) {
+		List<OrderSpecifier<?>> orders = new ArrayList<>();
+
+		for (Sort.Order order : pageable.getSort()) {
+			PathBuilder<?> entityPath = new PathBuilder<>(post.getType(), post.getMetadata());
+			orders.add(
+				new OrderSpecifier(order.isAscending() ? Order.ASC : Order.DESC, entityPath.get(order.getProperty()))
+			);
+		}
+		return orders;
+	}
+}

backend-board/src/main/java/com/backendboard/domain/post/respository/ViewCountRedisRepository.java

@@ -8,6 +8,4 @@ public interface ViewCountRedisRepository {
 	Map<Object, Object> getEntries();
 
 	void incrementCount(String postId);
-
-	Long getIncrementCount(String postId);
 }