show [global | session] status [like ‘xxx‘];
global选项，查看mysql所有连接状态
session选项，查看当前连接状态，默认session选项
flush status;可以将很多状态值重置清零。
获取mysql用户进程总数
ps -ef |awk ‘{print $1}‘ |grep mysql |grep -v "grep" |wc -l
查看mysql当前连接数
netstat -an |grep 3306 |grep "ESTABLISHED" |wc -l
查看主机性能状态
uptime
11:03:30 up 91 days, 9:48, 3 users, load average: 0.70, 0.91, 2.63
查看服务器启动时长，用户数，负载
top vmstat，top 查看cpu使用率
vmstat iostat 查看io状态
free -h 查看内存使用情况
数据库性能状态查询:
1)QPS每秒query量
show global status like ‘Question%‘;
+---------------+----------+
| Variable_name | Value |
+---------------+----------+
| Questions | 39661402 |
+---------------+----------+
2)TPS每秒事务量
show global status like ‘Com_commit‘;
+---------------+---------+
| Variable_name | Value |
+---------------+---------+
| Com_commit | 8495153 |
+---------------+---------+
show global status like ‘Com_rollback‘;
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| Com_rollback | 0 |
+---------------+-------+
(3)key Buffer 命中率
mysql>show global status like ‘key%‘;
key_buffer_read_hits = (1-key_reads / key_read_requests) * 100%
key_buffer_write_hits = (1-key_writes / key_write_requests) * 100%
(4)InnoDB Buffer命中率
mysql> show status like ‘innodb_buffer_pool_read%‘;
innodb_buffer_read_hits = (1 - innodb_buffer_pool_reads / innodb_buffer_pool_read_requests) * 100%
(5)Query Cache命中率
mysql> show status like ‘Qcache%‘;
Query_cache_hits = (Qcahce_hits / (Qcache_hits + Qcache_inserts )) * 100%;
(6)Table Cache状态量
mysql> show global status like ‘open%‘;
比较 open_tables 与 opend_tables 值
(7)Thread Cache 命中率
mysql> show global status like ‘Thread%‘;
mysql> show global status like ‘Connections‘;
Thread_cache_hits = (1 - Threads_created / connections ) * 100%
(8)锁定状态
mysql> show global status like ‘%lock%‘;
Table_locks_waited/Table_locks_immediate=0.3% 如果这个比值比较大的话，说明表锁造成的阻塞比较严重
Innodb_row_lock_waits innodb行锁，太大可能是间隙锁造成的
(9)复制延时量
mysql > show slave status
查看延时时间
(10) Tmp Table 状况(临时表状况)
mysql > show status like ‘Create_tmp%‘;
Created_tmp_disk_tables/Created_tmp_tables比值最好不要超过10%，如果Created_tmp_tables值比较大，
可能是排序句子过多或者是连接句子不够优化
(11) Binlog Cache 使用状况
mysql > show status like ‘Binlog_cache%‘;
如果Binlog_cache_disk_use值不为0 ，可能需要调大 binlog_cache_size大小
(12) Innodb_log_waits 量
mysql > show status like ‘innodb_log_waits‘;
Innodb_log_waits值不等于0的话，表明 innodb log buffer 因为空间不足而等待
13)show variables like ‘%timeout%‘;查看连接超时配置