Merge pull request #111 from Kid-Bean/refactor/lhj/optimization

refactor: WordQuiz 쿼리 최적화

src/main/java/soongsil/kidbean/server/wordquiz/application/WordQuizService.java

@@ -3,9 +3,9 @@
 
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
+import org.springframework.data.domain.PageRequest;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
-import soongsil.kidbean.server.global.util.RandNumUtil;
 import soongsil.kidbean.server.member.domain.Member;
 import soongsil.kidbean.server.member.exception.MemberNotFoundException;
 import soongsil.kidbean.server.member.repository.MemberRepository;
@@ -21,6 +21,7 @@
 import soongsil.kidbean.server.wordquiz.repository.WordRepository;
 
 import java.util.List;
+import java.util.concurrent.ThreadLocalRandom;
 
 import static soongsil.kidbean.server.member.exception.errorcode.MemberErrorCode.MEMBER_NOT_FOUND;
 import static soongsil.kidbean.server.quizsolve.application.vo.QuizType.WORD_QUIZ;
@@ -44,15 +45,13 @@ public class WordQuizService {
      * @return 랜덤 문제가 들어 있는 DTO
      */
     public WordQuizSolveListResponse selectRandomWordQuiz(Long memberId, Integer quizNum) {
+        long count = wordQuizRepository.countByMemberId(memberId);
+        int randomOffset = ThreadLocalRandom.current().nextInt((int) (count / quizNum));
 
-        Member member = memberRepository.findById(memberId)
-                .orElseThrow(() -> new MemberNotFoundException(MEMBER_NOT_FOUND));
-
-        int totalQuizNum = getWordQuizCount(member);
+        List<Long> randomQuizIds = wordQuizRepository.findRandomQuizIds(memberId, PageRequest.of(randomOffset, quizNum));
 
         List<WordQuizSolveResponse> wordQuizSolveResponseList =
-                RandNumUtil.generateRandomNumbers(0, totalQuizNum - 1, quizNum).stream()
-                        .map(quizIdx -> generateRandomWordQuizPage(member, quizIdx))
+                wordQuizRepository.findByIdsWithWords(randomQuizIds).stream()
                         .map(WordQuizSolveResponse::from)
                         .toList();
 
@@ -64,7 +63,7 @@ private int getWordQuizCount(Member member) {
     }
 
     private WordQuiz generateRandomWordQuizPage(Member member, int quizIdx) {
-        return wordQuizRepository.findSingleResultByMember(member, (long) quizIdx).get(0);
+        return wordQuizRepository.findSingleResultByMember(member, PageRequest.of(quizIdx, 1)).get(0);
     }
 
     @Transactional

src/main/java/soongsil/kidbean/server/wordquiz/domain/WordQuiz.java

@@ -10,6 +10,8 @@
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.ThreadLocalRandom;
+
 import soongsil.kidbean.server.quizsolve.domain.type.QuizCategory;
 
 @Table(name = "word_quiz")
@@ -36,6 +38,12 @@ public class WordQuiz {
     @Enumerated(EnumType.STRING)
     private Level level;
 
+    @Column(name = "is_default")
+    private Boolean isDefault;
+
+    @Column(name = "rand_val")
+    private Long randVal;
+
     @JoinColumn(name = "member_id")
     @ManyToOne(fetch = FetchType.LAZY)
     private Member member;
@@ -44,14 +52,16 @@ public class WordQuiz {
     private List<Word> words = new ArrayList<>();
 
     @Builder
-    public WordQuiz(QuizCategory quizCategory, String title, String answer, Level level, Member member,
-                    List<Word> words) {
+    public WordQuiz(QuizCategory quizCategory, String title, String answer, Level level,
+                    Boolean isDefault, Member member, List<Word> words) {
         this.quizCategory = quizCategory;
         this.title = title;
         this.answer = answer;
         this.level = level;
+        this.isDefault = isDefault;
         this.member = member;
         this.words = words;
+        this.randVal = ThreadLocalRandom.current().nextLong(Long.MAX_VALUE);
     }
 
     public void updateWordQuiz(String title, String answer) {

src/main/java/soongsil/kidbean/server/wordquiz/dto/response/WordQuizSolveListResponse.java

@@ -1,8 +1,16 @@
 package soongsil.kidbean.server.wordquiz.dto.response;
 
+import lombok.Builder;
+
 import java.util.List;
 
+@Builder
 public record WordQuizSolveListResponse(
         List<WordQuizSolveResponse> wordQuizSolveResponseList
 ) {
-}
+    public static WordQuizSolveListResponse from(List<WordQuizSolveResponse> wordQuizSolveResponseList) {
+        return WordQuizSolveListResponse.builder()
+                .wordQuizSolveResponseList(wordQuizSolveResponseList)
+                .build();
+    }
+}

src/main/java/soongsil/kidbean/server/wordquiz/repository/WordQuizRepository.java

@@ -1,5 +1,6 @@
 package soongsil.kidbean.server.wordquiz.repository;
 
+import org.springframework.data.domain.Pageable;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.jpa.repository.Query;
 import org.springframework.stereotype.Repository;
@@ -15,8 +16,17 @@ public interface WordQuizRepository extends JpaRepository<WordQuiz, Long> {
     @Query("SELECT count(*) FROM WordQuiz wq WHERE wq.member = :member OR wq.member.role = 'ADMIN'")
     Integer countByMemberOrAdmin(Member member);
 
-    @Query("SELECT wq FROM WordQuiz wq JOIN FETCH wq.words WHERE wq.quizId = :quizId AND wq.member = :member OR wq.member.role = 'ADMIN'")
-    List<WordQuiz> findSingleResultByMember(Member member, Long quizId);
+    @Query("SELECT wq FROM WordQuiz wq JOIN FETCH wq.words WHERE wq.member = :member OR wq.member.role = 'ADMIN'")
+    List<WordQuiz> findSingleResultByMember(Member member, Pageable pageable);
+
+    @Query("SELECT COUNT(wq) FROM WordQuiz wq WHERE wq.member.memberId = :memberId OR wq.isDefault = TRUE")
+    long countByMemberId(Long memberId);
+
+    @Query("SELECT wq.quizId FROM WordQuiz wq WHERE wq.member.memberId = :memberId OR wq.isDefault = TRUE ORDER BY wq.randVal")
+    List<Long> findRandomQuizIds(Long memberId, Pageable pageable);
+
+    @Query("SELECT wq FROM WordQuiz wq JOIN FETCH wq.words w WHERE wq.quizId IN :quizIds ORDER BY wq.randVal")
+    List<WordQuiz> findByIdsWithWords(List<Long> quizIds);
 
     Optional<WordQuiz> findByQuizIdAndMember_MemberId(Long quizId, Long memberId);