템플릿 생성, 수정 쿼리 성능 개선

backend/src/main/java/codezap/tag/domain/Tag.java

@@ -5,6 +5,8 @@
 import jakarta.persistence.GeneratedValue;
 import jakarta.persistence.GenerationType;
 import jakarta.persistence.Id;
+import jakarta.persistence.Index;
+import jakarta.persistence.Table;
 
 import codezap.global.auditing.BaseTimeEntity;
 import lombok.AccessLevel;
@@ -18,6 +20,7 @@
 @AllArgsConstructor
 @Getter
 @EqualsAndHashCode(of = "id", callSuper = false)
+@Table(indexes = @Index(name = "idx_tag_name", columnList = "name"))
 public class Tag extends BaseTimeEntity {
 
     @Id

backend/src/main/java/codezap/tag/repository/TagRepository.java

@@ -13,7 +13,7 @@ public interface TagRepository {
 
     Optional<Tag> findByName(String name);
 
-    List<String> findNameByNamesIn(List<String> names);
+    List<Tag> findByNameIn(List<String> names);
 
     Tag save(Tag tag);
 

backend/src/main/java/codezap/tag/service/TagService.java

@@ -1,5 +1,6 @@
 package codezap.tag.service;
 
+import java.util.ArrayList;
 import java.util.List;
 
 import org.springframework.stereotype.Service;
@@ -25,25 +26,22 @@ public class TagService {
 
     @Transactional
     public void createTags(Template template, List<String> tagNames) {
-        List<String> existingTags = tagRepository.findNameByNamesIn(tagNames);
-        templateTagRepository.saveAll(
-                existingTags.stream()
-                        .map(tagRepository::fetchByName)
-                        .map(tag -> new TemplateTag(template, tag))
-                        .toList()
-        );
+        List<Tag> existingTags = new ArrayList<>(tagRepository.findByNameIn(tagNames));
+        List<String> existNames = existingTags.stream()
+                .map(Tag::getName)
+                .toList();
 
         List<Tag> newTags = tagRepository.saveAll(
                 tagNames.stream()
-                        .filter(tagName -> !existingTags.contains(tagName))
+                        .filter(name -> !existNames.contains(name))
                         .map(Tag::new)
                         .toList()
         );
-        templateTagRepository.saveAll(
-                newTags.stream()
-                        .map(tag -> new TemplateTag(template, tag))
-                        .toList()
-        );
+        existingTags.addAll(newTags);
+
+        for (Tag existingTag : existingTags) {
+            templateTagRepository.save(new TemplateTag(template, existingTag));
+        }
     }
 
     public List<Tag> findAllByTemplate(Template template) {

backend/src/main/java/codezap/template/domain/TemplateTag.java

@@ -5,6 +5,7 @@
 import jakarta.persistence.Embeddable;
 import jakarta.persistence.EmbeddedId;
 import jakarta.persistence.Entity;
+import jakarta.persistence.FetchType;
 import jakarta.persistence.JoinColumn;
 import jakarta.persistence.ManyToOne;
 import jakarta.persistence.MapsId;
@@ -36,12 +37,12 @@ private static class TemplateTagId implements Serializable {
     @EmbeddedId
     private TemplateTagId id;
 
-    @ManyToOne
+    @ManyToOne(fetch = FetchType.LAZY)
     @MapsId("templateId")
     @JoinColumn(name = "template_id")
     private Template template;
 
-    @ManyToOne
+    @ManyToOne(fetch = FetchType.LAZY)
     @MapsId("tagId")
     @JoinColumn(name = "tag_id")
     private Tag tag;

backend/src/main/resources/db/migration/V5__create_idx_tag_name.sql

@@ -0,0 +1 @@
+CREATE INDEX idx_tag_name ON tag(name);

backend/src/test/java/codezap/tag/repository/TagJpaRepositoryTest.java

@@ -3,7 +3,6 @@
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
-import java.util.List;
 import java.util.Optional;
 
 import org.junit.jupiter.api.DisplayName;
@@ -90,17 +89,4 @@ void findByNameFailByNotExistsId() {
             assertThat(actual).isEmpty();
         }
     }
-
-    @Test
-    @DisplayName("이름 목록 조회 성공 : 이름 목록에 포함된 모든 태그를 반환한다.")
-    void findNameByNamesIn() {
-        tagRepository.save(new Tag("태그1"));
-        tagRepository.save(new Tag("태그2"));
-        tagRepository.save(new Tag("태그3"));
-
-        List<String> actual = tagRepository.findNameByNamesIn(List.of("태그1", "태그3", "태그4"));
-
-        assertThat(actual).hasSize(2)
-                .containsExactly("태그1", "태그3");
-    }
 }

backend/src/test/java/codezap/template/repository/FakeTagRepository.java

@@ -30,17 +30,6 @@ public Tag fetchById(Long id) {
                 .orElseThrow(() -> new CodeZapException(HttpStatus.NOT_FOUND, "식별자 " + id + "에 해당하는 태그가 존재하지 않습니다."));
     }
 
-    @Override
-    public List<String> findNameByNamesIn(List<String> names) {
-        return names.stream()
-                .filter(this::existsByName)
-                .toList();
-    }
-
-    private boolean existsByName(String name) {
-        return tags.stream().anyMatch(tag -> Objects.equals(tag.getName(), name));
-    }
-
     @Override
     public Tag fetchByName(String name) {
         return findByName(name).orElseThrow(
@@ -52,6 +41,11 @@ public Optional<Tag> findByName(String name) {
         return tags.stream().filter(tag -> Objects.equals(tag.getName(), name)).findFirst();
     }
 
+    @Override
+    public List<Tag> findByNameIn(List<String> names) {
+        return List.of();
+    }
+
     @Override
     public <S extends Tag> List<S> saveAll(Iterable<S> entities) {
         entities.forEach(this::save);