If you try to import / restore some big MySQL database you may have encountered such error:
MySQL server has gone away (error 2006)
To fix it you would need to increase wait_timeout and max_allowed_packet:
wait_timeout = 6000 max_allowed_packet = 128M
It should fix the problem.
Create a log:
touch /var/log/mysqld-general.log
Set the permissions:
chown mysql:mysql /var/log/mysqld-general.log
Run in mysql console:
mysql> SET GLOBAL general_log_file='/var/log/mysqld-general.log'; mysql> SET GLOBAL general_log = 1;
‘show procecclist‘ can be quite long in MySQL. Here’s simple way to filer out sleeping processes:
mysql> pager grep -v Sleep mysql> show processlist;
By default MySQL server doesn’t rotate slow queries log. Probably the simplest way to get rid of slow log which takes gigabytes is to use logrotate. Here’s an example:
[root@marge ~]# cat /etc/logrotate.d/mysql-slow
/var/log/mysqld-slow.log {
weekly
missingok
rotate 1
nocompress
copytruncate
notifempty
create 644 mysql mysql
}
[root@marge ~]#
If you need more than one rotated log adjust rotate values.