상속 구조 내에서 Querydsl로 특정 타입의 엔티티에만 조인

안녕하세요, 질문이 있어서 글 남기게 되었습니다.

이런식으로 지점(branch)명에 맞는 공간(space)중 미팅룸 리스트를 보여주고
해당 미팅룸의 해당 날짜의 예약들도 보여주는 기능을 구현하고자

    @Override
    public List<Reservation> findReservationListByDateAndBranchName(LocalDateTime startDatetime, LocalDateTime endDateTime, String branchName) {

        return queryFactory
                .select(reservation)
                .from(reservation)
                .join(reservation.space, space).fetchJoin()
                .join(space.branch, branch)
                .where(branch.branchName.eq(branchName),
                        reservation.reservationStartDateTime.between(startDatetime, endDateTime),
                        space.dtype.eq("MeetingRoom")
                        )
                .fetch();
    }

이런 코드를 작성하였는데 아래와 같은 연관관계 때문에

Reservation Entity

@Getter
@Entity
@NoArgsConstructor(access = AccessLevel.PROTECTED)
@Table(name = "reservation")
public class Reservation extends BaseEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "reservation_id")
    private Long reservationId;

    @Column(name = "reservation_start_date_time")
    private LocalDateTime reservationStartDateTime;

    @Column(name = "reservation_end_date_time")
    private LocalDateTime reservationEndDateTime;

    @OneToMany(mappedBy = "reservation")
    private List<MemberReservation> memberReservations = new ArrayList<>();

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "space_id")
    private Space space;
}

Space Entity

@Getter
@Entity
@NoArgsConstructor(access = AccessLevel.PROTECTED)
@Inheritance(strategy = InheritanceType.JOINED)
@Table(name = "space")
@DiscriminatorColumn
public abstract class Space {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "space_id")
    private Long spaceId;

    @NotNull
    @Column(name = "space_name")
    private String spaceName;

    @NotNull
    @Column(name = "space_floor")
    private int spaceFloor;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "branch_id")
    private Branch branch;

    @OneToMany(mappedBy = "space")
    private List<Reservation> reservations = new ArrayList<>();

    @NotNull
    @Column(name = "dtype", insertable = false, updatable = false)
    private String dtype;
}

Space를 상속받는 FocusDesk, MeetingRoom, RechargingRoom

@Getter
@Entity
@NoArgsConstructor(access = AccessLevel.PROTECTED)
@Table(name = "focus_desk")
public class FocusDesk extends Space {
//추후에 해당 엔티티에 맞는 필드들 추가
}

@Getter
@Entity
@NoArgsConstructor(access = AccessLevel.PROTECTED)
@Table(name = "meeting_room")
public class MeetingRoom extends Space {

    @Column(name = "meeting_room_capacity")
    @Positive
    private int meetingRoomCapacity;
}

@Getter
@Entity
@NoArgsConstructor(access = AccessLevel.PROTECTED)
@Table(name = "recharging_room")
public class RechargingRoom extends Space {
//추후에 해당 엔티티에 맞는 필드들 추가
}

select
    r1_0.reservation_id,
    r1_0.created_date,
    r1_0.last_modified_date,
    r1_0.reservation_end_date_time,
    r1_0.reservation_start_date_time,
    s1_0.space_id,
    s1_0.dtype,
    s1_0.branch_id,
    s1_0.space_floor,
    s1_0.space_name,
    s1_2.meeting_room_capacity 
from
    reservation r1_0 
join
    (space s1_0 
left join
    focus_desk s1_1 
        on s1_0.space_id=s1_1.space_id 
left join
    meeting_room s1_2 
        on s1_0.space_id=s1_2.space_id 
left join
    recharging_room s1_3 
        on s1_0.space_id=s1_3.space_id) 
    on s1_0.space_id=r1_0.space_id 
join
    branch b1_0 
        on b1_0.branch_id=s1_0.branch_id 
where
    b1_0.branch_name=? 
    and r1_0.reservation_start_date_time between ? and ? 
    and s1_0.dtype=?

이런 쿼리가 나가게 됩니다.
처음에는 dtype 없이 MeetingRoom 만 join 하고 싶었지만
reservation.meetingRoom 이불가능하여(reservation은 space랑 매핑 되어있으니까)
불가능하여 이방법 밖에는 떠오르지 않았습니다.
문제는 위의 쿼리처럼 쓸모없는 테이블들을 강제로 조인한 후에 다시 where절의 dtype으로 구분을 해야한다는 것입니다.

    @Query("SELECT new com.example.sabujak.reservation.dto.ReservationQueryDto(r.reservationStartDateTime, r.reservationEndDateTime, s.spaceId, s.spaceFloor, s.spaceName, m.meetingRoomCapacity) " +
            "FROM Reservation r " +
            "JOIN r.space s " +
            "JOIN MeetingRoom m ON m.spaceId = s.spaceId " +
            "JOIN s.branch b " +
            "WHERE b.branchName = :branchName " +
            "AND r.reservationStartDateTime BETWEEN :startDateTime AND :endDateTime")

이런식의 jpql로는 해결이 가능하지만
추후에 정렬조건을 동적으로 받아야 하기에 querydsl을 사용해서 최대한 좋은 방향으로 사용하고 싶은데
어떻게 해야할지 잘 모르겠습니다