问题
I've updated the my.cnf file of my database with the following line: max_connections=200. I stopped and started the mysql service after that so that the changes would take effect.
But for some reason this change doesn't affect the database because if I run:
mysql> select @@max_connections
it shows that the max number of connections is 100.
Obviously there is some place else that manages this value. Where can I find it or what did I do wrong?
Thank you for your reply.
回答1:
Make sure the max_connections in under the [mysqld] section:
Ex:
[mysqld]
socket=/path/to/mysql.sock
datadir=/var/lib/mysql
max_connections=200
[client]
#mysql-client settings here..
回答2:
Try running mysqld --verbose --help to see which configuration file is actually read by mysqld and which parameters and values are used.
The output will look like this:
mysqld Ver 5.0.51a-24-log for debian-linux-gnu on x86_64 ((Debian))
Copyright (C) 2000 MySQL AB, by Monty and others
This software comes with ABSOLUTELY NO WARRANTY. This is free software,
and you are welcome to modify and redistribute it under the GPL license
Default options are read from the following files in the given order:
/etc/mysql/my.cnf ~/.my.cnf /usr/etc/my.cnf
The following groups are read: mysql_cluster mysqld server mysqld-5.0
Variables (--variable-name=value)
and boolean options {FALSE|TRUE} Value (after reading options)
--------------------------------- -----------------------------
...
To see what values a running MySQL server is using, type
'mysqladmin variables' instead of 'mysqld --verbose --help'.
回答3:
It may have to do with 'how' the mysql server is being shutdown and restarted. On my system if I use the mysqld daemon service to shutdown mysql (e.g. service mysqld stop), I get a shutdown notice, but a ps shows mysql is still running. Using a similar 'service mysqld restart', some of the changes to the my.cnf file get accepted, but many don't.
The other method of shutting down mysql is to use mysqladmin -u user -pPass shutdown. I noticed when I used this method, mysql was shutdown completely (no left overs in ps), and when I restarted the mysql server, all the changes to the my.cnf file were accepted.
回答4:
Changes to mysqld are not necessarily reflected in the mysql client! I changed a global variable assignment in my.cnf, restarted the service, and queried it in the mysql client. It returned the old value. When queried from a script, however, the value was in fact changed!
回答5:
If mysql starts as a Window service, check the 'Path to executable' setting on the windows service. (Services -> MYSQL56 -> Properties).
If the --defaults-file option is passed in, it could point to a completely different .ini file in a location that is NOT showing with 'mysqld --verbose --help'.
If you remove the --defaults-file option from the service startup parameters, it will go through the list of ini files as listed with mysqld --verbose --help.
来源：https://stackoverflow.com/questions/9004400/mysql-modification-in-my-cnf-doesnt-take-effect