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mysql8000+分页点击任何一页响应控制在3-4s之间,请问如何继续优化?

时间:2021-07-01 10:21:17 帮助过:5人阅读

采用的优化方法:

  1. limit优化,先取出分页对应的ID,然后根据字段值,然后再limit

  2. 索引

  3. myisam引擎

附上代码:
查询数据总数:

下图是查询分页对应的ID:

下图是查询结果:

---------------2016.7.6 17:47更新--------------------
like那个地方确实不该要,已经做了处理,不该要的不要了。代码图也更新了。现在响应能保持在2.5s以下

执行计划如下:这是第一条语句,查询数据总量

SELECT `r`.`id` FROM (`samplerecord` as r) LEFT JOIN `statementsample` as s ON `r`.`sample_id`=`s`.`id` LEFT JOIN `breed` as b ON `s`.`food_id`=`b`.`id` LEFT JOIN `user` as u ON `r`.`user_id`=`u`.`id` WHERE `s`.`code` != ''


第二条语句 查询分页首位字段ID

SELECT `r`.`id` as id FROM (`samplerecord` as r) LEFT JOIN `statementsample` as s ON `r`.`sample_id`=`s`.`id` LEFT JOIN `breed` as b ON `s`.`food_id`=`b`.`id` LEFT JOIN `user` as u ON `r`.`user_id`=`u`.`id` WHERE `s`.`code` != '' ORDER BY `id` DESC LIMIT 1 OFFSET 5988

第三条语句:查询数据结果集

SELECT `r`.`id` as id, `s`.`code` as code, `b`.`breed_name`, `r`.`state`, `u`.`username`, `r`.`recordtime`, `r`.`remark` FROM (`samplerecord` as r) LEFT JOIN `statementsample` as s ON `r`.`sample_id`=`s`.`id` LEFT JOIN `breed` as b ON `s`.`food_id`=`b`.`id` LEFT JOIN `user` as u ON `r`.`user_id`=`u`.`id` WHERE `s`.`code` != '' AND `r`.`id` < '109541' ORDER BY `id` DESC LIMIT 12

请各位大神帮忙分析下...

回复内容:

采用的优化方法:

  1. limit优化,先取出分页对应的ID,然后根据字段值,然后再limit

  2. 索引

  3. myisam引擎

附上代码:
查询数据总数:

下图是查询分页对应的ID:

下图是查询结果:

---------------2016.7.6 17:47更新--------------------
like那个地方确实不该要,已经做了处理,不该要的不要了。代码图也更新了。现在响应能保持在2.5s以下

执行计划如下:这是第一条语句,查询数据总量

SELECT `r`.`id` FROM (`samplerecord` as r) LEFT JOIN `statementsample` as s ON `r`.`sample_id`=`s`.`id` LEFT JOIN `breed` as b ON `s`.`food_id`=`b`.`id` LEFT JOIN `user` as u ON `r`.`user_id`=`u`.`id` WHERE `s`.`code` != ''


第二条语句 查询分页首位字段ID

SELECT `r`.`id` as id FROM (`samplerecord` as r) LEFT JOIN `statementsample` as s ON `r`.`sample_id`=`s`.`id` LEFT JOIN `breed` as b ON `s`.`food_id`=`b`.`id` LEFT JOIN `user` as u ON `r`.`user_id`=`u`.`id` WHERE `s`.`code` != '' ORDER BY `id` DESC LIMIT 1 OFFSET 5988

第三条语句:查询数据结果集

SELECT `r`.`id` as id, `s`.`code` as code, `b`.`breed_name`, `r`.`state`, `u`.`username`, `r`.`recordtime`, `r`.`remark` FROM (`samplerecord` as r) LEFT JOIN `statementsample` as s ON `r`.`sample_id`=`s`.`id` LEFT JOIN `breed` as b ON `s`.`food_id`=`b`.`id` LEFT JOIN `user` as u ON `r`.`user_id`=`u`.`id` WHERE `s`.`code` != '' AND `r`.`id` < '109541' ORDER BY `id` DESC LIMIT 12

请各位大神帮忙分析下...

能不能把sql,执行计划贴出来

在事务里执行会提高效率的

1.先把表连接查询拆成简单查询
2.like有没有必要?

初步来看3个sql:

1.总量的sql,samplerecord没走任何索引,全表扫描,必然会慢些
2.查询id的sql,排序+全表,预计也慢
3.最后有一个应该还好

所以整个来说就是避免全表扫描,如果确实要全表数据,那么limit不会慢到哪儿去。
最终猜测,code!=''条件筛选性较高,也就是有很多这类条件,导致的筛选比较慢,试试加个索引。

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