refactor: 성능 개선

1. 쿼리 1회 감소
2. select 2번 -> join 1번 쿼리

main/src/main/java/org/sopt/makers/crew/main/entity/meeting/MeetingRepository.java

@@ -3,6 +3,7 @@
 import static org.sopt.makers.crew.main.global.exception.ErrorStatus.NOT_FOUND_MEETING;
 
 import java.util.List;
+import java.util.Optional;
 
 import org.sopt.makers.crew.main.global.exception.BadRequestException;
 import org.springframework.data.jpa.repository.JpaRepository;
@@ -28,6 +29,17 @@ default Meeting findByIdOrThrow(Integer meetingId) {
 			.orElseThrow(() -> new BadRequestException(NOT_FOUND_MEETING.getErrorCode()));
 	}
 
+	default Meeting findByIdWithUserOrThrow(Integer meetingId) {
+		return findByIdWithUser(meetingId)
+			.orElseThrow(() -> new BadRequestException(NOT_FOUND_MEETING.getErrorCode()));
+	}
+
+	@Query("SELECT m "
+		+ "FROM Meeting m "
+		+ "JOIN fetch m.user "
+		+ "WHERE m.id =:meetingId ")
+	Optional<Meeting> findByIdWithUser(Integer meetingId);
+
 	@Query("SELECT m FROM Meeting m JOIN FETCH m.user ORDER BY m.id DESC LIMIT 20")
 	List<Meeting> findTop20ByOrderByIdDesc();
 }

main/src/main/java/org/sopt/makers/crew/main/meeting/v2/service/MeetingV2ServiceImpl.java

@@ -216,8 +216,8 @@ public MeetingV2CreateMeetingResponseDto createMeeting(MeetingV2CreateMeetingBod
 	@Override
 	@Transactional
 	public MeetingV2ApplyMeetingResponseDto applyMeeting(MeetingV2ApplyMeetingDto requestBody, Integer userId) {
-		Meeting meeting = meetingRepository.findByIdOrThrow(requestBody.getMeetingId());
-		User user = userRepository.findByIdOrThrow(userId);
+		Meeting meeting = meetingRepository.findByIdWithUserOrThrow(requestBody.getMeetingId());
+		User user = meeting.getUser();
 		CoLeaders coLeaders = new CoLeaders(coLeaderRepository.findAllByMeetingId(meeting.getId()));
 
 		List<Apply> applies = applyRepository.findAllByMeetingId(meeting.getId());
@@ -379,18 +379,16 @@ public AppliesCsvFileUrlResponseDto getAppliesCsvFileUrl(Integer meetingId, List
 
 	@Override
 	public MeetingV2GetMeetingByIdResponseDto getMeetingById(Integer meetingId, Integer userId) {
-		User user = userRepository.findByIdOrThrow(userId);
-
-		Meeting meeting = meetingRepository.findByIdOrThrow(meetingId);
-		User meetingLeader = userRepository.findByIdOrThrow(meeting.getUserId());
+		Meeting meeting = meetingRepository.findByIdWithUserOrThrow(meetingId);
+		User meetingLeader = meeting.getUser();
 		CoLeaders coLeaders = new CoLeaders(coLeaderRepository.findAllByMeetingId(meetingId));
 
 		Applies applies = new Applies(
 			applyRepository.findAllByMeetingIdWithUser(meetingId, List.of(WAITING, APPROVE, REJECT), ORDER_ASC));
 
-		Boolean isHost = meeting.checkMeetingLeader(user.getId());
-		Boolean isApply = applies.isApply(meetingId, user.getId());
-		Boolean isApproved = applies.isApproved(meetingId, user.getId());
+		Boolean isHost = meeting.checkMeetingLeader(userId);
+		Boolean isApply = applies.isApply(meetingId, userId);
+		Boolean isApproved = applies.isApproved(meetingId, userId);
 		boolean isCoLeader = coLeaders.isCoLeader(meetingId, userId);
 		long approvedCount = applies.getApprovedCount(meetingId);