Question

我有一个查询，它在一台机器上运行25秒，在另一台机器上运行0.00秒。

编辑-只需升级mysql即可解决此问题。出于历史目的留有疑问。

扩展解释说明它在不良系统的第一行上拉了2084行，而在其他所有步骤上都拉了1或2行？在好的系统上，它们都是1到3行。

慢查询发生在具有MySQL 5.5.56且具有row_format = COMPACT的虚拟实例（AWS）上。

我使用mysqldump将整个数据库移到了系统上。它是功能更强大的桌面，MySQL版本5.7.22，导入后为row_format = DYNAMIC。

表结构是一个非常基本的外键设置，用于“批处理具有事务”，“事务具有项目”和“项目具有itemexceptions”。

这是查询（从Django模型自动生成的累积查询）

SELECT  COUNT(DISTINCT `decision_batch`.`id`)
    FROM  `decision_batch`
    INNER JOIN  `decision_transaction`
            ON (`decision_batch`.`id` = `decision_transaction`.`batch_id`)
    INNER JOIN  `decision_item`
            ON (`decision_transaction`.`id` = `decision_item`.`transaction_id`)
    WHERE  `decision_item`.`id` IN (
        SELECT  U0.`id`
            FROM  `decision_item` U0
            INNER JOIN  `decision_transaction` U1
                 ON (U0.`transaction_id` = U1.`id`)
            LEFT OUTER JOIN  `decision_itemexception` U2
                 ON (U0.`id` = U2.`item_id`)
            WHERE  U1.`batch_id` IN (2266)
            GROUP BY  U0.`id`, U0.`transaction_id`, U0.`item_type`,
                      U0.`sequence`, U0.`applied_amount`, U0.`accept`
            ORDER BY  NULL  );

扩展说明显示了不良系统上的“依赖子查询”，但在良好系统上一直“简单”：

| id | select_type        | table                | type  | possible_keys       | key                             | key_len | ref                              | rows | filtered | Extra                        |
|  1 | PRIMARY            | decision_batch       | index | PRIMARY       | decision_batch_c81d214          | 4       | NULL                             | 2084 |   100.00 | Using index                        |
|  1 | PRIMARY            | decision_transaction | ref   | PRIMARY,decision_transaction_58f424c5,batch_transaction,transaction_accept | transaction_accept              | 4       | cloudbox.decision_batch.id       |    3 |   100.00 | Using index                        |
|  1 | PRIMARY            | decision_item        | ref   | decision_item_45d19ab3       | decision_item_45d19ab3          | 4       | cloudbox.decision_transaction.id |    1 |   100.00 | Using where; Using index                     
|  2 | DEPENDENT SUBQUERY | U1                   | ref   | PRIMARY,decision_transaction_58f424c5,batch_transaction,transaction_accept | decision_transaction_58f424c5   | 4       | const                            |    2 |   100.00 | Using index; Using temporary; Using filesort |
|  2 | DEPENDENT SUBQUERY | U0                   | ref   | decision_item_45d19ab3       | decision_item_45d19ab3          | 4       | cloudbox.U1.id                   |    1 |   100.00 |                        |
|  2 | DEPENDENT SUBQUERY | U2                   | ref   | decision_itemexception_67b70d25,item       | decision_itemexception_67b70d25 | 4       | cloudbox.U0.id                   |    1 |   100.00 | Using index    |    3 |   100.00 | Using index; End temporary   |

如果有帮助，请显示创建表输出（省略数据行）

decision_batch

CREATE TABLE `decision_batch` (
`id` int(11) NOT NULL AUTO_INCREMENT,
...
PRIMARY KEY (`id`),
KEY `decision_batch_c81d214` (`box_id`),
KEY `decision_batch_1c65f4ce` (`finalized_by_id`),
KEY `dec_opt_idx` (`finalized`,`batch_status`,`box_id`),
CONSTRAINT `decision_batch_ibfk_1`
       FOREIGN KEY (`box_id`) REFERENCES `lockbox_lockbox` (`id`),
CONSTRAINT `finalized_by_id_refs_id_31bb6e9b`
       FOREIGN KEY (`finalized_by_id`) REFERENCES `config_user` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2267 DEFAULT CHARSET=latin1

decision_transaction

CREATE TABLE `decision_transaction` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`batch_id` int(11) NOT NULL,
...
PRIMARY KEY (`id`),
KEY `decision_transaction_58f424c5` (`batch_id`),
KEY `batch_transaction` (`id`,`batch_id`),
KEY `transaction_accept` (`batch_id`,`accept`),
CONSTRAINT `batch_id_refs_id_24828b6d`
       FOREIGN KEY (`batch_id`) REFERENCES `decision_batch` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=19306 DEFAULT CHARSET=latin1

decision_item

CREATE TABLE `decision_item` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`transaction_id` int(11) NOT NULL,
...
PRIMARY KEY (`id`),
KEY `decision_item_45d19ab3` (`transaction_id`),
CONSTRAINT `transaction_id_refs_id_56c7fe1d`
       FOREIGN KEY (`transaction_id`) REFERENCES `decision_transaction` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=45544 DEFAULT CHARSET=latin1

decision_itemexception

CREATE TABLE `decision_itemexception` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`item_id` int(11) NOT NULL,
...
PRIMARY KEY (`id`),
KEY `decision_itemexception_67b70d25` (`item_id`),
KEY `item` (`item_id`),
KEY `field` (`field_id`),
CONSTRAINT `field`
       FOREIGN KEY (`field_id`) REFERENCES `decision_field` (`id`)
           ON DELETE NO ACTION ON UPDATE NO ACTION,
CONSTRAINT `item`
       FOREIGN KEY (`item_id`) REFERENCES `decision_item` (`id`)
           ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB AUTO_INCREMENT=44589 DEFAULT CHARSET=latin1

mysql查询性能不好不一致

0 个答案: