MariaDB 10.1 Order By + Limit 不一致

Question

当在 MariaDB 10.1.18 上运行一个有限制的查询订单时，我得到一个错误的订单。

观察没有 LIMIT 语句的查询：

select advert_id, published, id from vacancies order by published asc;

+-----------+-----------+----+
| advert_id | published | id |
+-----------+-----------+----+
|    328377 |         0 | 70 |
|    328844 |         0 | 80 |
|    325263 |         0 | 41 |
|    325774 |         0 | 40 |
|    325775 |         0 | 39 |
|    325929 |         0 | 38 |
|    325885 |         0 | 37 |
|    325901 |         0 | 36 |
|    325920 |         0 | 35 |
|    325917 |         0 | 34 |
|    325922 |         0 | 33 |
|    325889 |         0 | 32 |
|    325927 |         0 | 31 |
|    325238 |         0 | 43 |
|    325244 |         0 | 45 |
|    328365 |         0 | 71 |
|    328446 |         0 | 72 |
|    328362 |         0 | 68 |
|    323602 |         0 | 55 |
|    324250 |         0 | 54 |
|    324254 |         0 | 53 |
|    324911 |         0 | 52 |

使用 LIMIT 语句：

select advert_id, published, id from vacancies order by published asc limit 10;

+-----------+-----------+----+
| advert_id | published | id |
+-----------+-----------+----+
|    327830 |         0 |  1 |
|    326865 |         0 | 18 |
|    327328 |         0 |  9 |
|    326877 |         0 | 16 |
|    326783 |         0 | 21 |
|    326779 |         0 | 17 |
|    326774 |         0 | 15 |
|    326864 |         0 | 20 |
|    326788 |         0 | 14 |
|    326767 |         0 | 19 |
+-----------+-----------+----+

两个查询中发布的顺序不同。

为了比较，我运行在MariaDB 5.5.50上进行了相同的查询，发现order by +限制正确returns与order by查询的结果相同。所以据我了解，这个问题是 MariaDB 特有的，并且只存在于较新的版本中。

此外，我也运行进行了相同的查询，但在具有许多不同值的 varchar 字段上进行排序，在这种情况下，顺序是正确的。所以我认为这个问题只适用于对具有很多相同值的字段进行限制排序。

有谁知道是否有办法解决这个问题？也许是 MariaDB 中的设置？

仅供参考：

Table结构：

+------------------+------------------+------+-----+---------+----------------+
| Field            | Type             | Null | Key | Default | Extra          |
+------------------+------------------+------+-----+---------+----------------+
| id               | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
| advert_id        | int(11)          | YES  |     | NULL    |                |
| published        | tinyint(1)       | NO   |     | 0       |                |
| (other fields omitted)

查询解释：

explain select advert_id, published, id from vacancies order by published asc;
+------+-------------+-----------+------+---------------+------+---------+------+------+----------------+
| id   | select_type | table     | type | possible_keys | key  | key_len | ref  | rows | Extra          |
+------+-------------+-----------+------+---------------+------+---------+------+------+----------------+
|    1 | SIMPLE      | vacancies | ALL  | NULL          | NULL | NULL    | NULL |   52 | Using filesort |
+------+-------------+-----------+------+---------------+------+---------+------+------+----------------+

explain select advert_id, published, id from vacancies order by published asc limit 10;
+------+-------------+-----------+------+---------------+------+---------+------+------+----------------+
| id   | select_type | table     | type | possible_keys | key  | key_len | ref  | rows | Extra          |
+------+-------------+-----------+------+---------------+------+---------+------+------+----------------+
|    1 | SIMPLE      | vacancies | ALL  | NULL          | NULL | NULL    | NULL |   52 | Using filesort |
+------+-------------+-----------+------+---------------+------+---------+------+------+----------------+

按问题排序的版本：

mysql  Ver 15.1 Distrib 10.1.18-MariaDB, for debian-linux-gnu (x86_64) using readline 5.2

没有按发行顺序排列的版本：

mysql  Ver 15.1 Distrib 5.5.50-MariaDB, for debian-linux-gnu (x86_64) using readline 5.2

Answer 1

您没有指定要获取前十行。由于有很多行 published 等于 0 MariaDB 可以自由选择其中的一些。如果您想要特定的订单，请尝试：

SELECT advert_id, published, id FROM vacancies ORDER BY published asc, id LIMIT 10;

MariaDB 10.1 Order By + Limit 不一致

MariaDB 10.1 Order By + Limit inconsistencies

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