SQL analysis (query interception analysis for SQL optimization)

Catalog

mysqldump Use （ Slow query analysis ） 

Kill users

  View

---

 

mysqldump Use （ Slow query analysis ） 

1. Open slow query log

SHOW VARIABLES LIKE 'slow_query_log';

# Open slow query log 
SET GLOBAL slow_query_log=1;

# Threshold for slow queries 
SHOW VARIABLES LIKE 'long_query_time';
SET long_query_time=0.1

2. Find the slow query log first

cd /var/lib/mysql

find common.sock In the file is the slow query log

 3. Use log analysis tools

mysqldumpsslw --help

  Analyze as we do sql Optimization can use this log analysis

  such as ： Find the three slowest

mysqldumpslow -s c -t 3 -a

3. Find the corresponding sql Then go to centralized processing , You can go to sql Console explain The sql, Then proceed sql Index optimization

mysqldumpslow Parametric analysis

  Common references for work ：

 Get the most returned recordset 10 individual SQL
mysqldumpslow -s r -t 10 /var/lib/mysql/atguigu-slow.log
 
 The most visited 10 individual SQL
mysqldumpslow -s c -t 10 /var/lib/mysql/atguigu-slow.log
 
 Get the top... In chronological order 10 There are left connected query statements in the bar 
mysqldumpslow -s t -t 10 -g "left join" /var/lib/mysql/atguigu-slow.log
 
 It is also recommended to use these commands in conjunction with  |  and more  Use  , Otherwise, the screen may explode 
mysqldumpslow -s r -t 10 /var/lib/mysql/atguigu-slow.log | more

Kill users

# View user processes 
SHOW PROCESSLIST

KILL 3

  View

I'm only responsible for showing , There is no need to publish the program  

 1. Create view

CREATE VIEW view_name 
AS
SELECT column_name(s)
FROM table_name
WHERE condition
 

2. After creating the view , Our future queries can be directly queried in the view （ What is encapsulated in the view itself is our sql）

View view

DELIMITER $$

ALTER ALGORITHM=UNDEFINED DEFINER=`root`@`%` SQL SECURITY DEFINER VIEW `view_test` AS 
SELECT
  `t_emp`.`id`     AS `id`,
  `t_emp`.`name`   AS `name`,
  `t_emp`.`age`    AS `age`,
  `t_emp`.`deptld` AS `deptld`,
  `t_emp`.`empno`  AS `empno`
FROM `t_emp`$$

DELIMITER ;

Query the data according to the view

SELECT * FROM view_test