✨ [feat] #17 대용량 데이터 처리

src/test/java/org/example/expert/domain/user/service/UserInsertTest.java

@@ -0,0 +1,79 @@
+package org.example.expert.domain.user.service;
+
+import jakarta.persistence.EntityManager;
+import jakarta.persistence.PersistenceContext;
+import org.example.expert.domain.user.enums.UserRole;
+import org.example.expert.domain.user.entity.User;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestInstance;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.annotation.Rollback;
+import org.springframework.transaction.annotation.Transactional;
+
+import javax.sql.DataSource;
+import java.sql.Connection;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.UUID;
+
+@SpringBootTest
+@Rollback(false)
+@TestInstance(TestInstance.Lifecycle.PER_CLASS)
+public class UserInsertTest {
+
+    @PersistenceContext
+    private EntityManager entityManager;
+
+    private static final int TOTAL_COUNT = 1_000_000;
+    private static final int BATCH_SIZE = 1000;
+
+
+    @Autowired
+    private DataSource dataSource;
+
+    @Test
+    void printDataSourceInfo() throws Exception {
+        try (Connection conn = dataSource.getConnection()) {
+            System.out.println("연결된 DB URL: " + conn.getMetaData().getURL());
+            System.out.println("사용자명: " + conn.getMetaData().getUserName());
+        }
+    }
+
+
+    @Test
+    @Transactional
+    void insertMillionUsersWithJpa() {
+        System.out.println("100만 건 유저 insert 시작");
+
+        Set<String> nicknames = new HashSet<>();
+
+        for (int i = 0; i < TOTAL_COUNT;) {
+            String nickname = UUID.randomUUID().toString().substring(0, 10);
+            if (!nicknames.add(nickname)) continue;
+
+            String email = nickname + "@test.com";
+
+            User user = User.builder()
+                    .nickname(nickname)
+                    .email(email)
+                    .password("password")
+                    .userRole(UserRole.USER)
+                    .build();
+
+
+            entityManager.persist(user);
+
+            if (++i % BATCH_SIZE == 0) {
+                entityManager.flush();
+                entityManager.clear();
+                System.out.println("▶ 진행 중: " + i + "명");
+            }
+        }
+
+        entityManager.flush();
+        entityManager.clear();
+
+        System.out.println("100만 명 유저 insert 완료");
+    }
+}