Rails MySQL查询时间混乱

概述我有一个计数计算查询,我在我的Rails应用程序中运行了数千次,对于db中的每个客户.当我在MySQL客户端中运行查询并禁用查询缓存时,查询所需的时间不超过1毫秒.但是,当我从启用了查询输出的Rails控制台运行我的任务时,我注意到在前几次查询非常快的时候,其余查询的时间突然从不到1毫秒突然增加到大约180毫秒.我已经减少了innodb_buffer_poo

我有一个计数计算查询,我在我的Rails应用程序中运行了数千次,对于db中的每个客户.

当我在MySQL客户端中运行查询并禁用查询缓存时,查询所需的时间不超过1毫秒.

但是,当我从启用了查询输出的Rails控制台运行我的任务时,我注意到在前几次查询非常快的时候,其余查询的时间突然从不到1毫秒突然增加到大约180毫秒.

我已经减少了innodb_buffer_pool_size,以便查看行为的变化,但没有注意到任何事情.

这是控制台的输出：

  EmailCampaignReport::Open Columns (143.2ms)   SHOW FIELDS FROM `email_campaign_report_opens`  sql (0.3ms)   SELECT count(*) AS count_all FROM `email_campaign_report_opens` WHERE (customer_ID = 332330)   sql (0.2ms)   SELECT count(*) AS count_all FROM `email_campaign_report_opens` WHERE (customer_ID = 333333)   sql (0.2ms)   SELECT count(*) AS count_all FROM `email_campaign_report_opens` WHERE (customer_ID = 332661)   sql (0.1ms)   SELECT count(*) AS count_all FROM `email_campaign_report_opens` WHERE (customer_ID = 332326)   sql (0.1ms)   SELECT count(*) AS count_all FROM `email_campaign_report_opens` WHERE (customer_ID = 332665)   sql (0.2ms)   SELECT count(*) AS count_all FROM `email_campaign_report_opens` WHERE (customer_ID = 336027)   sql (0.2ms)   SELECT count(*) AS count_all FROM `email_campaign_report_opens` WHERE (customer_ID = 333001)   sql (0.2ms)   SELECT count(*) AS count_all FROM `email_campaign_report_opens` WHERE (customer_ID = 331983)   sql (0.1ms)   SELECT count(*) AS count_all FROM `email_campaign_report_opens` WHERE (customer_ID = 332668)   sql (0.1ms)   SELECT count(*) AS count_all FROM `email_campaign_report_opens` WHERE (customer_ID = 332316)   sql (0.1ms)   SELECT count(*) AS count_all FROM `email_campaign_report_opens` WHERE (customer_ID = 332325)   sql (0.1ms)   SELECT count(*) AS count_all FROM `email_campaign_report_opens` WHERE (customer_ID = 331995)   sql (0.2ms)   SELECT count(*) AS count_all FROM `email_campaign_report_opens` WHERE (customer_ID = 334007)   sql (0.2ms)   SELECT count(*) AS count_all FROM `email_campaign_report_opens` WHERE (customer_ID = 333326)   sql (0.1ms)   SELECT count(*) AS count_all FROM `email_campaign_report_opens` WHERE (customer_ID = 332998)   sql (183.9ms)   SELECT count(*) AS count_all FROM `email_campaign_report_opens` WHERE (customer_ID = 334673)   sql (183.7ms)   SELECT count(*) AS count_all FROM `email_campaign_report_opens` WHERE (customer_ID = 336751)   sql (183.6ms)   SELECT count(*) AS count_all FROM `email_campaign_report_opens` WHERE (customer_ID = 333334)   sql (186.3ms)   SELECT count(*) AS count_all FROM `email_campaign_report_opens` WHERE (customer_ID = 332663)   sql (183.7ms)   SELECT count(*) AS count_all FROM `email_campaign_report_opens` WHERE (customer_ID = 332328)   sql (186.3ms)   SELECT count(*) AS count_all FROM `email_campaign_report_opens` WHERE (customer_ID = 332659) 

该表中的customer_ID列有一个索引.

有没有人有任何关于为什么会发生这种情况的建议？

谢谢

最佳答案为什么不运行一个查询？

SELECT customer_ID,count(*) AS count_all FROM `email_campaign_report_opens` GROUP BY customer_ID;

如果您有这么多记录,您担心将它们全部归还,那么请分批进行,但我只是不明白为什么您真的想要为每个客户运行此查询. 总结

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