Mysql状态信息查询

[TOC]

## 一.连接相关
查看连接线程相关的系统变量的设置值
`show variables like 'thread%';`

查看系统被连接的次数
`show status like 'connections';`
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| Connections | 620 |
+---------------+-------+

当前系统中连接线程的状态值
`show status like '%thread%';`
+------------------------+-------+
| Variable_name | Value |
+------------------------+-------+
| Delayed_insert_threads | 0 |
| Slow_launch_threads | 0 |
| Threads_cached | 3 |
| Threads_connected | 4 |
| Threads_created | 7 |
| Threads_running | 1 |
+------------------------+-------+

系统启动到现在共接受到客户端的连接620次，共创建了7个连接线程，当前有1个连接线程处于和客户端连接的状态，而3个连接状态的线程中只有一个处于 active 状态，即只有一个正在处理客户端提交的请求，。而在Thread Cache池中共缓存了3个连接线程。

Thread Cache 命中率：
Thread_Cache_Hit = (Connections - Threads_created) / Connections * 100%;

## 二.show status
![file](http://linkdevops.oss-cn-beijing.aliyuncs.com/wp-content/uploads/2020/05/image-1589159323769.png)

## 三.其它
检测mysql server是否正常提供服务
`mysqladmin -u sky -ppwd -h localhost ping`

获取mysql当前的几个状态值
`mysqladmin -u sky -ppwd -h localhost status`

获取数据库当前的连接信息
`mysqladmin -u sky -ppwd -h localhost processlist`

获取当前数据库的连接数
`mysql -u root -p123456 -BNe "select host,count(host) from processlist group by host;" information_schema`

显示mysql的uptime
`mysql -e"SHOW STATUS LIKE '%uptime%'"|awk '/ptime/{ calc = $NF / 3600;print $(NF-1), calc"Hour" }'`

查看数据库的大小
`select table_schema,round(sum(data_length+index_length)/1024/1024,4) from information_schema.tables group by table_schema;`

查看某个表的列信息
`mysql -u <user> --password=<password> -e "SHOW COLUMNS FROM <table>" <database> | awk '{print $1}' | tr "\n" "," | sed 's/,$//g'`

mysql dump数据导出
`mysqldump -uroot -T/tmp/mysqldump test test_outfile --fields-enclosed-by=\" --fields-terminated-by=,`

mysql数据导入
`mysqlimport --user=name --password=pwd test --fields-enclosed-by=\" --fields-terminated-by=, /tmp/test_outfile.txt LOAD DATA INFILE '/tmp/test_outfile.txt' INTO TABLE test_outfile FIELDS TERMINATED BY '"' ENCLOSED BY ',';`

查看当前数据库的状态
mysql>`show status`

mysqlcheck 工具程序可以检查(check),修 复( repair),分 析( analyze)和优化(optimize)MySQL Server 中的表
`mysqlcheck -u root -p123456 --all-databases`

mysql qps查询  QPS = Questions(or Queries) / Seconds
mysql>`SHOW /*!50000 GLOBAL */ STATUS LIKE "Questions"`
mysql>`SHOW /*!50000 GLOBAL */ STATUS LIKE "Queries"`

mysql Key Buffer 命中率  key_buffer_read_hits = (1 - Key_reads / Key_read_requests) * 100%  key_buffer_write_hits= (1 - Key_writes / Key_write_requests) * 100%
mysql>`SHOW /*!50000 GLOBAL */ STATUS LIKE "Key%"`

mysql Innodb Buffer 命中率  innodb_buffer_read_hits=(1-Innodb_buffer_pool_reads/Innodb_buffer_pool_read_requests) * 100%
mysql>`SHOW /*!50000 GLOBAL */ STATUS LIKE "Innodb_buffer_pool_read%"`

mysql Query Cache 命中率 Query_cache_hits= (Qcache_hits / (Qcache_hits + Qcache_inserts)) * 100%
mysql>`SHOW /*!50000 GLOBAL */ STATUS LIKE "Qcache%"`

mysql Table Cache 状态量
mysql>`SHOW /*!50000 GLOBAL */ STATUS LIKE "Open%"`

mysql Thread Cache 命中率  Thread_cache_hits = (1 - Threads_created / Connections) * 100%  正常来说,Thread Cache 命中率要在 90% 以上才算比较合理。
mysql>`SHOW /*!50000 GLOBAL */ STATUS LIKE "Thread%"`

mysql 锁定状态:锁定状态包括表锁和行锁两种,我们可以通过系统状态变量获得锁定总次数,锁定造成其他线程等待的次数,以及锁定等待时间信息
mysql>`SHOW /*!50000 GLOBAL */ STATUS LIKE "%lock%"`

mysql 复制延时量 在slave节点执行
mysql>`SHOW SLAVE STATUS`

mysql Tmp table 状况 Tmp Table 的状况主要是用于监控 MySQL 使用临时表的量是否过多,是否有临时表过大而不得不从内存中换出到磁盘文件上
mysql>`SHOW /*!50000 GLOBAL */ STATUS LIKE "Created_tmp%"`

mysql Binlog Cache 使用状况:Binlog Cache 用于存放还未写入磁盘的 Binlog 信 息 。
mysql>`SHOW /*!50000 GLOBAL */ STATUS LIKE "Binlog_cache%"`

mysql nnodb_log_waits 量:Innodb_log_waits 状态变量直接反应出 Innodb Log Buffer 空间不足造成等待的次数
mysql>`SHOW /*!50000 GLOBAL */ STATUS LIKE "Innodb_log_waits`