list processes running in MySQL

login to mysql as a root:
mysql -uroot -p
end execute:
mysql> show processlist;
will show you list of processes running in MySQL
and using  \G delimiter will present processes in more readable format.
mysql> show processlist \G

Provided by: ForthScale systems, scalable infrastructure experts

Upgrading PHP in CentOS 5

CentOS 5.x comes with PHP 5.1, this version is outdated and you probably would want to upgrade it. I used Atomic repository.

You can add it by running following command:

wget -q -O - http://www.atomicorp.com/installers/atomic.sh | sh

Now you can update PHP:

yum update php

yum update php-mcrypt

(you might also need to update mysql)

Verify version of running PHP:

php -v

And that all modules working as order:

php -m

Restart Apache, you are all set.

Provided by:SiQ systems, Cloud experts

"SQL Error: 13: Can't create/write to file" on other then /tmp directories (apparmor)

If you get SQL Error: 13 after changing tmpdir parameter in you my.cnf first check permissions in a new directory. If permissions are correct you might be having an issue with AppArmor. AppArmor is a GNU security module for the Linux kernel and it might prevent MySQL from writing to the new directory.

Run: aa-status

To verify if it`s on. If so you will get something like:

profiles are loaded

profiles are in enforce mode

Edit this file:

/etc/apparmor.d/usr.sbin.mysqld

and append your new temp directory in the end.

####

/usr/sbin/mysqld {

...

/new_tmp/ r,

/new_tmp/* rw,

}

Reload AppArmor with:

/etc/init.d/apparmor reload

Thats it.

Fix (repair) MySQL replication in case of duplicate items

If you as i am using MySQL replication mechanism, master-slave or master-master replication you sometimes loose replication due to duplicate entries.

You can fix it by simply skipping the record:
1. log into MySQL:
mysql -u root -p
2. in MySQL shell stop slave replication
mysql> STOP SLAVE;
3. skip the affected record
mysql> SET GLOBAL SQL_SLAVE_SKIP_COUNTER = 1;
4. start slave replication process
mysql> START SLAVE;
5. verify that replication is working:
mysql> SHOW SLAVE STATUS \G
6. exit MySQL shell:
mysql> quit;


Provided by:SiQ systems, Cloud experts

MySQL and debian-sys-maint account

If for some reason your debian-sys-maint account is unset in MySQL, during MySQL start you will have connect to server error. You might need to set this account in the MySQL server itself.
cat /etc/mysql/debian.cnf to get the password value from the file.
Then connect to the DB
mysql -u root -p
and execute:
GRANT ALL PRIVILEGES ON *.* TO 'debian-sys-maint'@'localhost' IDENTIFIED BY 'YOUR_PASSWORD' WITH GRANT OPTION