MySQL Troubleshooting Common Commands

Here are some mysql troubleshooting common commands.

show global status like'uptime';

show variables like'%log%';
SHOW FULL PROCESSLIST;
SHOW VARIABLES LIKE'%max_connections%';
SHOW STATUS LIKE'%Connection%';
show status like'Threads%';

mysql> show status like'Threads%';
+-------------------+-------+
| Variable_name | Value |
+-------------------+-------+
| Threads_cached | 58 |
| Threads_connected | 57 | ###This value refers to the number of open connections
| Threads_created | 3676 |
| Threads_running | 4 | ###This value refers to the number of active connections, this value is generally much lower than the connected
+-------------------+-------+

Threads_connected is the same as show processlist, indicating the current number of connections. To be precise, Threads_running represents the current concurrent number

This is the maximum number of connections currently set to query the database
mysql> show variables like'%max_connections%';
+-----------------+-------+
| Variable_name | Value |
+-----------------+-------+
| max_connections | 1000 |
+-----------------+-------+

You can set the maximum number of database connections in /etc/my.cnf
[mysqld]
max_connections = 1000


Command: show processlist;
If it is a root account, you can see the current connections of all users. If it is another ordinary account, you can only see the connections you occupy.
show processlist; only list the first 100, if you want to list all, please use show full processlist;
MySQL> show processlist;