From 190fbe835fe6ab2b60c2edf2c9637abb321a0d04 Mon Sep 17 00:00:00 2001
From: ByungCheol <kenneth73510@nurier.co.kr>
Date: Thu, 2 Jul 2026 01:47:08 +0900
Subject: [PATCH] =?UTF-8?q?perf(account):=20=EB=82=B4=EC=97=AD=20=EB=AA=A9?=
 =?UTF-8?q?=EB=A1=9D=20=ED=83=9C=EA=B7=B8=20=EC=A1=B0=ED=9A=8C=20N+1=20?=
 =?UTF-8?q?=E2=86=92=20=EB=B0=B0=EC=B9=98=20=EB=8B=A8=EC=9D=BC=20=EC=BF=BC?=
 =?UTF-8?q?=EB=A6=AC=EB=A1=9C=20=EA=B0=9C=EC=84=A0?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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list() 에서 항목마다 findTagNamesByEntryId() 를 개별 호출하던 N+1 을
findTagsByEntryIds() 배치 쿼리 1회로 대체.
항목 수가 많을 때 타임아웃/과부하 방지.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 .../web/account/mapper/AccountEntryMapper.java   |  3 +++
 .../sb/web/account/service/AccountService.java   | 16 +++++++++++++---
 src/main/resources/mapper/AccountEntryMapper.xml | 12 ++++++++++++
 3 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/src/main/java/com/sb/web/account/mapper/AccountEntryMapper.java b/src/main/java/com/sb/web/account/mapper/AccountEntryMapper.java
index 107e633..1b1181f 100644
--- a/src/main/java/com/sb/web/account/mapper/AccountEntryMapper.java
+++ b/src/main/java/com/sb/web/account/mapper/AccountEntryMapper.java
@@ -93,4 +93,7 @@ public interface AccountEntryMapper {
     int deleteEntryTagsByEntryId(@Param("entryId") Long entryId);
 
     List<String> findTagNamesByEntryId(@Param("entryId") Long entryId);
+
+    /** 복수 항목의 태그를 한 번에 조회 — {entryId, tagName} 맵 반환 */
+    List<Map<String, Object>> findTagsByEntryIds(@Param("entryIds") List<Long> entryIds);
 }
diff --git a/src/main/java/com/sb/web/account/service/AccountService.java b/src/main/java/com/sb/web/account/service/AccountService.java
index 2868871..078b5e8 100644
--- a/src/main/java/com/sb/web/account/service/AccountService.java
+++ b/src/main/java/com/sb/web/account/service/AccountService.java
@@ -53,9 +53,19 @@ public class AccountService {
 
     public List<AccountEntryResponse> list(Long memberId, Integer year, Integer month,
                                            String type, String category, Long walletId, String keyword, Long tagId) {
-        return mapper.findByMember(memberId, year, month,
-                        blankToNull(type), blankToNull(category), walletId, blankToNull(keyword), tagId).stream()
-                .map(this::toResponse)
+        List<AccountEntry> entries = mapper.findByMember(memberId, year, month,
+                blankToNull(type), blankToNull(category), walletId, blankToNull(keyword), tagId);
+        if (entries.isEmpty()) return List.of();
+        // 태그 N+1 방지: 한 번에 모든 entry 의 태그를 조회 후 Map 으로 그룹화
+        List<Long> ids = entries.stream().map(AccountEntry::getId).toList();
+        Map<Long, List<String>> tagsByEntry = new HashMap<>();
+        for (Map<String, Object> row : mapper.findTagsByEntryIds(ids)) {
+            Long eid = ((Number) row.get("entryId")).longValue();
+            String name = (String) row.get("tagName");
+            tagsByEntry.computeIfAbsent(eid, k -> new ArrayList<>()).add(name);
+        }
+        return entries.stream()
+                .map(e -> AccountEntryResponse.from(e, tagsByEntry.getOrDefault(e.getId(), List.of())))
                 .toList();
     }
 
diff --git a/src/main/resources/mapper/AccountEntryMapper.xml b/src/main/resources/mapper/AccountEntryMapper.xml
index 93f32d9..0150e41 100644
--- a/src/main/resources/mapper/AccountEntryMapper.xml
+++ b/src/main/resources/mapper/AccountEntryMapper.xml
@@ -234,4 +234,16 @@
         ORDER BY t.name
     </select>
 
+    <!-- 복수 항목의 태그를 한 번에 조회 — {entry_id, tag_name} 행 반환 -->
+    <select id="findTagsByEntryIds" resultType="map">
+        SELECT aet.entry_id AS entryId, t.name AS tagName
+        FROM account_tag t
+        JOIN account_entry_tag aet ON aet.tag_id = t.id
+        WHERE aet.entry_id IN
+        <foreach item="id" collection="entryIds" open="(" separator="," close=")">
+            #{id}
+        </foreach>
+        ORDER BY aet.entry_id, t.name
+    </select>
+
 </mapper>