MariaDB、PBXT 和神秘的查询结果

Question

首先，这是表格：

CREATE TABLE `outlet_tags` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `importer_id` int(11) NOT NULL,
  `outlet_id` int(11) NOT NULL,
  `code` varchar(20) NOT NULL,
  `postcode` varchar(15) DEFAULT NULL,
  `tag_set` varchar(45) DEFAULT NULL,
  `tag_type` varchar(45) DEFAULT NULL,
  `tag_details` varchar(100) DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `fk_report_outlet_tags_1` (`importer_id`),
  KEY `fk_report_outlet_tags_2` (`outlet_id`),
  KEY `outlet_tag_set` (`tag_set`),
  KEY `outlet_tag_type` (`tag_type`),
  KEY `outlet_tag_details` (`tag_details`),
  CONSTRAINT `fk_report_outlet_tags_1` FOREIGN KEY (`importer_id`) REFERENCES `importers` (`id`),
  CONSTRAINT `fk_report_outlet_tags_2` FOREIGN KEY (`outlet_id`) REFERENCES `outlets` (`id`)
) ENGINE=PBXT DEFAULT CHARSET=utf8;

任何人都可以解释为什么字段值会根据以下查询中使用的条件而变化吗？如果引擎是玛丽亚，就不会发生这种情况。

select * from outlet_tags where code=1503 and outlet_id=407 limit 3;
+------+-------------+-----------+------+----------+---------+-----------------+----------------+
| id   | importer_id | outlet_id | code | postcode | tag_set | tag_type        | tag_details    |
+------+-------------+-----------+------+----------+---------+-----------------+----------------+
|  222 |           1 |       407 | 1503 | XXX XXX  | outlet  | Make up         | Make up        |
|  675 |           1 |       407 | 1503 | XXX XXX  | outlet  | Approved Status | Approved       |
| 1619 |           1 |       407 | 1503 | XXX XXX  | outlet  | Retail Area     | No Retail Area |
+------+-------------+-----------+------+----------+---------+-----------------+----------------+
3 rows in set (0.00 sec)

select * from outlet_tags where code=1503 and importer_id=1 limit 3;
+------+-------------+-----------+------+----------+---------+-----------------+----------------+
| id   | importer_id | outlet_id | code | postcode | tag_set | tag_type        | tag_details    |
+------+-------------+-----------+------+----------+---------+-----------------+----------------+
|  222 |           1 |       407 | 1503 | XXX XXX  | outlet  | Make up         | Make up        |
|  675 |           1 |       407 | 1503 | XXX XXX  | outlet  | Approved Status | Approved       |
| 1619 |           1 |       407 | 1503 | XXX XXX  | outlet  | Retail Area     | No Retail Area |
+------+-------------+-----------+------+----------+---------+-----------------+----------------+
3 rows in set (0.00 sec)

select * from outlet_tags where importer_id=1 and outlet_id=407 limit 3;
+------+-------------+-----------+------+----------+---------+----------+-------------+
| id   | importer_id | outlet_id | code | postcode | tag_set | tag_type | tag_details |
+------+-------------+-----------+------+----------+---------+----------+-------------+
|  222 |           1 |       407 | 1503 | NULL     | NULL    | NULL     | NULL        |
|  675 |           1 |       407 | 1503 | NULL     | NULL    | NULL     | NULL        |
| 1619 |           1 |       407 | 1503 | NULL     | NULL    | NULL     | NULL        |
+------+-------------+-----------+------+----------+---------+----------+-------------+
3 rows in set (0.00 sec)

更新：从 MariaDB 5.5 开始 PBXT 已作为存储引擎

Answer 1

尝试在查询中使用 ORDER BY。

不同的引擎可能以不同的顺序返回行，具体取决于行的检索方式。