N+1 문제 해결

build.gradle

@@ -36,6 +36,7 @@ subprojects {
 
 		// Test
 		testImplementation 'org.springframework.boot:spring-boot-starter-test'
+		testImplementation 'com.h2database:h2'
 
 		// Actuator
 		implementation 'org.springframework.boot:spring-boot-starter-actuator'

module-domain/src/main/java/com/fourcut/diary/diary/service/DiaryService.java

@@ -80,12 +80,9 @@ public void enrollDiary(String socialId, String imageUrl, String title) {
 
     @Transactional
     public void createNextDayDiaries(LocalDate nextDay) {
-        List<User> allUser = userRetriever.getAllUsers();
-        for (User user : allUser) {
-            if (diaryRetriever.existsDiary(user, nextDay)) {
-                continue;
-            }
-            diaryModifier.createDiary(nextDay, user);
+        List<User> allUser = userRetriever.getAllUsersWithoutDiary(nextDay);
+        for (User u : allUser) {
+            diaryModifier.createDiary(nextDay, u);
         }
     }
 }

module-domain/src/main/java/com/fourcut/diary/notification/repository/NotificationRepository.java

@@ -3,10 +3,15 @@
 import com.fourcut.diary.notification.domain.Notification;
 import com.fourcut.diary.user.domain.User;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
 
+import java.util.List;
 import java.util.Optional;
 
 public interface NotificationRepository  extends JpaRepository<Notification, Long> {
 
     Optional<Notification> findByUser(User user);
+
+    @Query("SELECT DISTINCT n FROM Notification n JOIN FETCH n.user")
+    List<Notification> findAllWithUser();
 }

module-domain/src/main/java/com/fourcut/diary/notification/service/NotificationRetriever.java

@@ -37,4 +37,8 @@ public Notification getTodayNotification(User user) {
     public List<Notification> getAllNotifications() {
         return notificationRepository.findAll();
     }
+
+    public List<Notification> getAllNotificationsWithUser() {
+        return notificationRepository.findAllWithUser();
+    }
 }

module-domain/src/main/java/com/fourcut/diary/notification/service/NotificationService.java

@@ -41,7 +41,7 @@ public PictureCaptureInfoDto getTakePictureInfoByUser(String socialId) {
 
     @Transactional
     public void updateNotificationTime(LocalDate nextDay) {
-        List<Notification> notifications = notificationRetriever.getAllNotifications();
+        List<Notification> notifications = notificationRetriever.getAllNotificationsWithUser();
         notifications.forEach(notification -> {
             List<LocalDateTime> timeSlots = NotificationTimeSlotUtil.getRandomTimeSlot(notification.getUser(), nextDay);
             notificationModifier.updateNextDayNotificationTime(notification, timeSlots);

module-domain/src/main/java/com/fourcut/diary/user/repository/UserRepository.java

@@ -1,8 +1,12 @@
 package com.fourcut.diary.user.repository;
 
 import com.fourcut.diary.user.domain.User;
+import io.lettuce.core.dynamic.annotation.Param;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
 
+import java.time.LocalDate;
+import java.util.List;
 import java.util.Optional;
 
 public interface UserRepository extends JpaRepository<User, Long>, UserRepositoryCustom {
@@ -13,6 +17,18 @@ public interface UserRepository extends JpaRepository<User, Long>, UserRepositor
     boolean existsBySocialId(String socialId);
     Optional<User> findBySocialId(String socialId);
 
+    @Query("""
+                SELECT u\s
+                FROM User u\s
+                WHERE NOT EXISTS (
+                    SELECT 1\s
+                    FROM Diary d\s
+                    WHERE d.user = u\s
+                    AND d.date = :nextDay
+                )
+            \s""")
+    List<User> findAllWithoutDiaryOn(@Param("nextDay") LocalDate nextDay);
+
     // UPDATE
 
     // DELETE

module-domain/src/main/java/com/fourcut/diary/user/service/UserRetriever.java

@@ -8,7 +8,7 @@
 import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Component;
 
-import java.time.LocalTime;
+import java.time.LocalDate;
 import java.util.List;
 
 @Component
@@ -34,7 +34,7 @@ public void checkExistUser(String socialId) {
         }
     }
 
-    public List<User> getAllUsers() {
-        return userRepository.findAll();
+    public List<User> getAllUsersWithoutDiary(LocalDate nextDay) {
+        return userRepository.findAllWithoutDiaryOn(nextDay);
     }
 }

module-notification/src/test/java/com/fourcut/diary/service/SchedulerServiceQueryCountTest.java

@@ -0,0 +1,126 @@
+package com.fourcut.diary.service;
+
+import com.fourcut.diary.diary.service.DiaryService;
+import com.fourcut.diary.notification.domain.Notification;
+import com.fourcut.diary.notification.repository.NotificationRepository;
+import com.fourcut.diary.notification.service.NotificationService;
+import com.fourcut.diary.user.domain.User;
+import com.fourcut.diary.user.repository.UserRepository;
+import jakarta.persistence.EntityManager;
+import jakarta.persistence.EntityManagerFactory;
+import org.hibernate.engine.spi.SessionFactoryImplementor;
+import org.hibernate.stat.Statistics;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.ActiveProfiles;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.time.LocalTime;
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+@SpringBootTest
+@Transactional
+@ActiveProfiles("test")
+public class SchedulerServiceQueryCountTest {
+
+    @Autowired
+    private EntityManagerFactory emf;
+
+    @Autowired
+    private EntityManager em;
+
+    @Autowired
+    private SchedulerService schedulerService;
+
+    @Autowired
+    private DiaryService diaryService;
+
+    @Autowired
+    private NotificationService notificationService;
+
+    @Autowired
+    private UserRepository userRepository;
+
+    @Autowired
+    private NotificationRepository notificationRepository;
+
+    private final LocalDate nextDay = LocalDate.now();
+
+    @BeforeEach
+    void setUpDummyDataAndEnableStats() {
+        SessionFactoryImplementor sf = emf.unwrap(SessionFactoryImplementor.class);
+        sf.getStatistics().setStatisticsEnabled(true);
+
+        notificationRepository.deleteAll();
+        userRepository.deleteAll();
+        em.flush(); em.clear();
+
+        List<User> users = IntStream.rangeClosed(1, 1000)
+                .mapToObj(i -> com.fourcut.diary.user.domain.User.newInstance(
+                        "social" + i,
+                        "nick"   + i,
+                        LocalDate.of(1990, 1, 1),
+                        com.fourcut.diary.user.domain.Gender.MALE,
+                        LocalTime.of(8, 0),
+                        LocalTime.of(20, 0),
+                        "arn"    + i,
+                        "token"  + i
+                ))
+                .collect(Collectors.toList());
+        userRepository.saveAll(users);
+        em.flush(); em.clear();
+
+        List<Notification> notis = users.stream()
+                .map(u -> {
+                    List<LocalDateTime> slots = Arrays.asList(
+                            nextDay.atTime( 9,  0),
+                            nextDay.atTime(12,  0),
+                            nextDay.atTime(15,  0),
+                            nextDay.atTime(18,  0)
+                    );
+
+                    return Notification.builder()
+                            .firstTimeSlot (slots.get(0))
+                            .secondTimeSlot(slots.get(1))
+                            .thirdTimeSlot (slots.get(2))
+                            .fourthTimeSlot(slots.get(3))
+                            .user(u)
+                            .build();
+                })
+                .collect(Collectors.toList());
+        notificationRepository.saveAll(notis);
+        em.flush(); em.clear();
+    }
+
+    @Test
+    void countQueriesCreateNextDayDiaries() {
+        Statistics stats = emf.unwrap(SessionFactoryImplementor.class).getStatistics();
+        stats.clear();
+
+        diaryService.createNextDayDiaries(nextDay);
+        em.flush();
+
+        long q = stats.getPrepareStatementCount();
+        System.out.println("createNextDayDiaries 쿼리 수: " + q);
+    }
+
+    @Test
+    void countQueriesUpdateNotificationTime() {
+        Statistics stats = emf.unwrap(SessionFactoryImplementor.class).getStatistics();
+        stats.clear();
+
+        notificationService.updateNotificationTime(nextDay);
+        em.flush();
+
+        long q = stats.getPrepareStatementCount();
+        System.out.println("updateNotificationTime 쿼리 수: " + q);
+    }
+}
+

module-notification/src/test/resources/application-test.yml

@@ -0,0 +1,19 @@
+spring:
+  datasource:
+    url: jdbc:h2:mem:testdb;DB_CLOSE_DELAY=-1;MODE=MySQL
+    driver-class-name: org.h2.Driver
+    username: sa
+    password:
+
+  jpa:
+    hibernate:
+      ddl-auto: create-drop
+    properties:
+      hibernate:
+        dialect: org.hibernate.dialect.H2Dialect
+        globally_quoted_identifiers: true
+
+logging:
+  level:
+    org.hibernate.SQL: DEBUG
+    org.hibernate.type.descriptor.sql.BasicBinder: TRACE