谨记:只对本次会话有效
-- 查看Profiling的状态
show variables like 'profiling';
-- 开启profile
set profiling=on;
-- 测试语句 1
SELECT * from emp GROUP BY id%10 limit 150000
-- 测试语句 2
select * from emp GROUP BY id%20 ORDER BY 5;
-- 查看执行sql的用时时间
show profiles;
-- 查看具体的sql语句执行的详细时间消耗
show profile cpu,block io for query 3;
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