스프링 데이터 페이징 활용1 - Querydsl 페이징 연동

스프링 데이터의 Page, Pageable을 활용해보자.
전체 카운트를 한번에 조회하는 단순한 방법
데이터 내용과 전체 카운트를 별도로 조회하는 방법

 

사용자 정의 인터페이스에 페이징 2가지 추가

public interface MemberRepositoryCustom {
    List<MemberTeamDto> search(MemberSearchCondition condition);
    Page<MemberTeamDto> searchPageSimple(MemberSearchCondition condition, Pageable pageable);
    Page<MemberTeamDto> searchComplex(MemberSearchCondition condition, Pageable pageable);
}

 

전체 카운트를 한번에 조회하는 단순한 방법
searchPageSimple(), fetchResults() 사용

@Override
public Page<MemberTeamDto> searchPageSimple(MemberSearchCondition condition, Pageable pageable) {
    QueryResults<MemberTeamDto> results = queryFactory
            .select(new QMemberTeamDto(
                    member.id,
                    member.username, member.age,
                    team.id,
                    team.name))
            .from(member)
            .leftJoin(member.team, team)
            .where(usernameEq(condition.getUsername()),
                    teamNameEq(condition.getTeamName()),
                    ageGoe(condition.getAgeGoe()),
                    ageLoe(condition.getAgeLoe()))
            .offset(pageable.getOffset())
            .limit(pageable.getPageSize())
            .fetchResults();

    List<MemberTeamDto> content = results.getResults();
    long total = results.getTotal();

    return new PageImpl<>(content, pageable, total);

}

Querydsl이 제공하는 fetchResults() 를 사용하면 내용과 전체 카운트를 한번에 조회할 수 있다.(실제 쿼리는 2번 호출)
fetchResult() 는 카운트 쿼리 실행시 필요없는 order by 는 제거한다.

 

 

 

데이터 내용과 전체 카운트를 별도로 조회하는 방법
searchPageComplex()

@Override
public Page<MemberTeamDto> searchComplex(MemberSearchCondition condition, Pageable pageable) {
    List<MemberTeamDto> content = queryFactory
            .select(new QMemberTeamDto(
                    member.id,
                    member.username, member.age,
                    team.id,
                    team.name))
            .from(member)
            .leftJoin(member.team, team)
            .where(usernameEq(condition.getUsername()),
                    teamNameEq(condition.getTeamName()),
                    ageGoe(condition.getAgeGoe()),
                    ageLoe(condition.getAgeLoe()))
            .offset(pageable.getOffset())
            .limit(pageable.getPageSize())
            .fetch();

    long total = queryFactory
            .select(member)
            .from(member)
            .leftJoin(member.team, team)
            .where(usernameEq(condition.getUsername()),
                    teamNameEq(condition.getTeamName()),
                    ageGoe(condition.getAgeGoe()),
                    ageLoe(condition.getAgeLoe()))
            .fetchCount();


    return new PageImpl<>(content, pageable, total);
}

전체 카운트를 조회 하는 방법을 최적화 할 수 있으면 이렇게 분리하면 된다. 

(예를 들어서 전체 카운트를조회할 때 조인 쿼리를 줄일 수 있다면 상당한 효과가 있다.)
코드를 리펙토링해서 내용 쿼리과 전체 카운트 쿼리를 읽기 좋게 분리하면 좋다

 

 

 

 

 

출처 : 김영한 JPA 스프링 데이터 강의