主要方法：
show status , show profile ,检查慢查询日志
# 检测执行的sql，具体那个位置比较慢
SELECT * FROM phone_sts
#数据库版本
SELECT VERSION();
#查询sql对资源的占用情况
SHOW profiles ;
#查询当前sql执行过程中的时间消耗
SHOW profile ;
SHOW profile block io,cpu FOR QUERY 31969
#检查profiling是否开启
SHOW VARIABLES LIKE '%pro%';
#开启
SET profiling=1;
SHOW profiles;
#c查询各个表占用大小
SELECT
table_schema AS 'Db Name',
ROUND( SUM( data_length + index_length ) / 1024 / 1024, 3 ) AS 'Db Size (MB)',
ROUND( SUM( data_free ) / 1024 / 1024, 3 ) AS 'Free Space (MB)'
FROM information_schema.tables
GROUP BY table_schema ;
SHOW DATABASES;
USE information_schema;
SHOW TABLES;
# 表超过1000行的
SELECT CONCAT(table_schema,'.',table_name) AS table_name,table_rows
FROM information_schema.tables
WHERE table_rows > 1000
ORDER BY table_rows DESC;
# 最大的10个表
SELECT CONCAT(table_schema,'.',table_name) table_name,
CONCAT(ROUND(data_length/(1024*1024),2),'M') data_length
FROM information_schema.TABLES
ORDER BY data_length DESC LIMIT 10;
# 查询一个sql语句的时间消耗在哪里
SET @query_id=1 ;
SELECT state,SUM(duration) AS total_R,
ROUND(
100*SUM(duration)/
(SELECT SUM(DURATION)
FROM information_schema.PROFILING
WHERE query_id=@query_id
),2) AS calls ,
SUM(duration )/COUNT(*) AS "R/Call"
FROM information_schema.PROFILING
WHERE query_id=@query_id
GROUP BY state
ORDER BY total_R DESC ;
# 查询一个sql语句的时间消耗在哪里
SET @query_id=31969 ;
SELECT state,SUM(duration) AS total_R,
ROUND(
100*SUM(duration)/
(SELECT SUM(DURATION)
FROM information_schema.PROFILING
),2) AS calls ,
SUM(duration )/COUNT(*) AS "R/Call"
FROM information_schema.PROFILING
GROUP BY state
ORDER BY total_R DESC ;