Mariadb布尔全文搜索否定逻辑？

使用Mariadb的FTS（全文搜索）时，以下逻辑非常有趣：

SELECT id, first_name, last_name FROM user 
WHERE MATCH (first_name, last_name) AGAINST ('-veli' IN BOOLEAN MODE);
Empty set (0.001 sec)

SELECT id, first_name, last_name FROM user 
WHERE MATCH (first_name, last_name) AGAINST ('lauri -veli' IN BOOLEAN MODE);
+----------+------------+-----------+
| id       | first_name | last_name |
+----------+------------+-----------+
| 15804835 | Lauri      | Ylikangas |
+----------+------------+-----------+
1 row in set (0.001 sec)

这种奇怪的现象是“ok”，但如何添加“universal set”，使结果与以下内容匹配

SELECT id, first_name, last_name FROM user
WHERE NOT MATCH (first_name, last_name) AGAINST ('-veli' IN BOOLEAN MODE);
...
213 rows in set (0.002 sec)

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建议写一个bug报告。这是他们有文档记录的“特性”，否定只会产生一组空记录。。。