基础知识
慢SQL官方定义
If a query takes longer than this many seconds, the server increments the Slow_queries status variable. If the slow query log is enabled, the query is logged to the slow query log file; Unit:Second.
阿里云控制台慢SQL参数
SQL优化原因与影响
•SQL优化原因:查询效率低的SQL(慢SQL)会占用机器大量的CPU、内存和IO资源,影响正常业务。