Add files via upload

internal/database/conversation.go

@@ -310,15 +310,14 @@ func (db *DB) ListConversations(limit, offset int, search string) ([]*Conversati
 	var err error
 	
 	if search != "" {
-		// 使用LIKE进行模糊搜索，搜索标题和消息内容
+		// 使用 EXISTS 子查询代替 LEFT JOIN + DISTINCT，避免大表笛卡尔积
 		searchPattern := "%" + search + "%"
-		// 使用DISTINCT避免重复，因为一个对话可能有多条消息匹配
 		rows, err = db.Query(
-			`SELECT DISTINCT c.id, c.title, COALESCE(c.pinned, 0), c.created_at, c.updated_at 
+			`SELECT c.id, c.title, COALESCE(c.pinned, 0), c.created_at, c.updated_at
 			 FROM conversations c
-			 LEFT JOIN messages m ON c.id = m.conversation_id
-			 WHERE c.title LIKE ? OR m.content LIKE ?
-			 ORDER BY c.updated_at DESC 
+			 WHERE c.title LIKE ?
+			    OR EXISTS (SELECT 1 FROM messages m WHERE m.conversation_id = c.id AND m.content LIKE ?)
+			 ORDER BY c.updated_at DESC
 			 LIMIT ? OFFSET ?`,
 			searchPattern, searchPattern, limit, offset,
 		)

internal/database/group.go

@@ -403,6 +403,35 @@ func (db *DB) UpdateGroupPinned(id string, pinned bool) error {
 	return nil
 }
 
+// GroupMapping 分组映射关系
+type GroupMapping struct {
+	ConversationID string `json:"conversationId"`
+	GroupID        string `json:"groupId"`
+}
+
+// GetAllGroupMappings 批量获取所有分组映射（消除 N+1 查询）
+func (db *DB) GetAllGroupMappings() ([]GroupMapping, error) {
+	rows, err := db.Query("SELECT conversation_id, group_id FROM conversation_group_mappings")
+	if err != nil {
+		return nil, fmt.Errorf("查询分组映射失败: %w", err)
+	}
+	defer rows.Close()
+
+	var mappings []GroupMapping
+	for rows.Next() {
+		var m GroupMapping
+		if err := rows.Scan(&m.ConversationID, &m.GroupID); err != nil {
+			return nil, fmt.Errorf("扫描分组映射失败: %w", err)
+		}
+		mappings = append(mappings, m)
+	}
+
+	if mappings == nil {
+		mappings = []GroupMapping{}
+	}
+	return mappings, nil
+}
+
 // UpdateConversationPinnedInGroup 更新对话在分组中的置顶状态
 func (db *DB) UpdateConversationPinnedInGroup(conversationID, groupID string, pinned bool) error {
 	pinnedValue := 0