今天例行查看日志,发现有个sql在本地查询速度较快,在服务器环境下查询速度较慢,达到了6s之多。说下优化思路,原本事先将子查询优化下,后来排查下,发现是mysql缓存问题。为以后排查问题涨了点知识。...优化sql语句优化mysql配置、一、sql优化优化前SELECTspace_id,max_temp,min_temp,avg_temp,create_time FROM( SELECT space_id..., max_temp, min_temp, avg_temp, create_time FROM t_data_history ORDER BY create_time DESC LIMIT 99999...) a GROUP BYa.space_id优化后SELECTa....b.circle_point,b.temperature FROM( SELECT max( create_time ) AS create_time, space_id FROM t_data_history a GROUP