WindValley

安装MySQL卸载#检查rpm -qa|grep mariadb#卸载rpm -e --nodeps mariadb-libs#复查rpm -qa|grep mariadb安装Yum Repositorywget http://dev.mysql.com/get/mysql57-community-release-el7-8.noarch.rpmyum -y install mysql57-community-release-el7-8.noarch.rpmyum clean all

SQL样例SELECT a, b, c, d, e, f, g, h FROM TableA WHERE b in ('AT105873A') AND type = '2' GROUP BY if(d is null, e, d) ORDER BY h ASC, g ASC老规矩explain sql截图中可以看出来，使用到了文件排序和临时表，在sql没办法优化的情况下该怎么提升响应时间呢Trace sql的执行过程SET OPTIMIZER_TRACE="enabled=on",END_MA

SQL样例其中i_uid是A表的水平拆分键，accesion是B表的水平拆分键select * from A a where a.i_uid in (select b.union_an from B b where b.accesion = ?)定位步骤以下操作均发生在物理mysql服务器的代理节点上（例如mycat）第一步explain sqlexplain select * from A a where a.i_uid in (select b.union_an from B b wher

获取mysql进程idps -ef | grep -i mysql实时查看mysql进程中占用CPU，内存最多的操作系统线程IDtop -p 2341 -H根据操作系统线程ID，查看mysql数据库中对应的线程IDselect thread_id,name ,PROCESSLIST_ID,THREAD_OS_ID from threads where thread_os_id = 2341 ;根据mysql数据库的线程ID获取sqlselect sql_text from perform