perf: 지연 로딩 연관을 배치로 읽어 회원 목록의 N+1 쿼리를 없앤다

src/main/resources/application.yml

@@ -16,6 +16,8 @@ spring:
     properties:
       hibernate:
         format_sql: true
+        # 지연 로딩 연관(회원의 직책·트랙 등)을 목록 크기만큼 한 번에 읽는다(N+1 방지).
+        default_batch_fetch_size: 100
     open-in-view: false
 
   # 배포는 컨테이너를 내렸다 올린다. 처리 중인 요청과 큐에 남은 비동기 메일(@Async)을 마치고 종료한다.

src/test/java/com/bcsdlab/bcsdinternalapiv2/member/MemberDirectoryQueryCountIntegrationTest.java

@@ -0,0 +1,105 @@
+package com.bcsdlab.bcsdinternalapiv2.member;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+import com.bcsdlab.bcsdinternalapiv2.IntegrationTestSupport;
+import com.bcsdlab.bcsdinternalapiv2.member.model.Member;
+import com.bcsdlab.bcsdinternalapiv2.member.model.MemberRole;
+import com.bcsdlab.bcsdinternalapiv2.member.model.MemberStatus;
+import com.bcsdlab.bcsdinternalapiv2.member.model.MemberType;
+import com.bcsdlab.bcsdinternalapiv2.member.model.Position;
+import com.bcsdlab.bcsdinternalapiv2.member.repository.MemberRepository;
+import com.bcsdlab.bcsdinternalapiv2.member.repository.PositionRepository;
+import com.bcsdlab.bcsdinternalapiv2.track.model.TrackMaster;
+import com.bcsdlab.bcsdinternalapiv2.track.repository.TrackMasterRepository;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import jakarta.persistence.EntityManagerFactory;
+import java.util.List;
+import org.hibernate.SessionFactory;
+import org.hibernate.stat.Statistics;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.MediaType;
+import org.springframework.security.crypto.password.PasswordEncoder;
+import org.springframework.test.context.TestPropertySource;
+
+/** 명부 목록은 회원 수와 무관하게 일정한 쿼리 수로 조회한다(회원마다 직책·트랙을 따로 읽지 않는다). */
+@TestPropertySource(properties = "spring.jpa.properties.hibernate.generate_statistics=true")
+class MemberDirectoryQueryCountIntegrationTest extends IntegrationTestSupport {
+
+    private static final int MEMBER_COUNT = 20;
+
+    @Autowired
+    private MemberRepository memberRepository;
+
+    @Autowired
+    private PositionRepository positionRepository;
+
+    @Autowired
+    private TrackMasterRepository trackMasterRepository;
+
+    @Autowired
+    private PasswordEncoder passwordEncoder;
+
+    @Autowired
+    private EntityManagerFactory entityManagerFactory;
+
+    @Test
+    void 명부_조회_쿼리_수는_회원_수에_비례하지_않는다() throws Exception {
+        List<TrackMaster> tracks = trackMasterRepository.findAll();
+        List<Position> positions = positionRepository.findAll();
+        for (int i = 0; i < MEMBER_COUNT; i++) {
+            memberRepository.save(Member.builder()
+                    .studentNumber("2030%04d".formatted(i))
+                    .name("명부" + i)
+                    .track(tracks.get(i % tracks.size()))
+                    .generation("24-하")
+                    .memberType(MemberType.REGULAR)
+                    .university("한국기술교육대학교")
+                    .department("컴퓨터공학부")
+                    .positions(positions.isEmpty() ? List.of() : List.of(positions.get(i % positions.size())))
+                    .email("dir" + i + "@bcsd.club")
+                    .phoneNumber("0100000%04d".formatted(i))
+                    .status(MemberStatus.ACTIVE)
+                    .role(MemberRole.MEMBER)
+                    .build());
+        }
+        String token = adminToken();
+
+        Statistics statistics = entityManagerFactory.unwrap(SessionFactory.class).getStatistics();
+        statistics.clear();
+        mockMvc.perform(get("/v1/admin/members").param("size", "50")
+                        .header("Authorization", "Bearer " + token))
+                .andExpect(status().isOk())
+                .andExpect(jsonPath("$.members.length()").value(MEMBER_COUNT + 1));
+
+        assertThat(statistics.getPrepareStatementCount()).isLessThan(15);
+    }
+
+    private String adminToken() throws Exception {
+        memberRepository.save(Member.builder()
+                .studentNumber("20309999")
+                .password(passwordEncoder.encode("Temp1234"))
+                .name("관리자")
+                .track(trackMasterRepository.findByCode("BACKEND").orElseThrow())
+                .generation("16")
+                .memberType(MemberType.MENTOR)
+                .university("한국기술교육대학교")
+                .department("컴퓨터공학부")
+                .email("admin@bcsd.club")
+                .phoneNumber("01099999999")
+                .status(MemberStatus.ACTIVE)
+                .role(MemberRole.ADMIN)
+                .build());
+        String body = mockMvc.perform(post("/v1/auth/login")
+                        .contentType(MediaType.APPLICATION_JSON)
+                        .content("{\"studentNumber\":\"20309999\",\"password\":\"Temp1234\",\"rememberMe\":false}"))
+                .andExpect(status().isOk())
+                .andReturn().getResponse().getContentAsString();
+        return new ObjectMapper().readTree(body).get("accessToken").asText();
+    }
+}