Wired Gorilla » MySQL

Linux Server Type: Restoring MySQL SimLink.

jada — Tue, 16 Feb 2010 07:08:04 +0000

If you’re unable to restart mysqld and troubleshooting the cause: if u log into SSH and go to /tmp you may see that there is no simlink

To create a simlink you can do the following:

cd /var/lib/mysql/
touch mysql.sock
chmod 1777 mysql.sock
chown mysql.mysql mysql.sock

Create a symlink for the sock file :-
ln -s /var/lib/mysql/mysql.sock /tmp

Restart mysql :- service mysql restart

Then your MySQL service should be back to normal.

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How To Set Up A Load-Balanced MySQL Cluster With MySQL 5.1

wiredgorilla — Sat, 18 Apr 2009 01:05:47 +0000

This tutorial is based on Falko Timme’s tutorial for MySQL Cluster 5.0. It shows how to configure a MySQL 5.1 cluster with five nodes: 1 x management, 2 x storage nodes and 2 x balancer nodes. This cluster is load-balanced by an Ultra Monkey package which provides heartbeat (for checking if the other node is still alive) and ldirectord (to split up the requests to the nodes of the MySQL cluster).

In this document I use Debian Etch 4.0 for all nodes. Therefore the setup might differ a bit for other distributions. The two data nodes were x64 to use all of the 8GB RAM. Servers were compiled from source so you should be able to make it running on any platform. The MySQL version I use in this setup is 5.1.24-rc. It’s a release candidate, but I wanted to use 5.1 to take advantage of Memory-Disk Based tables.

Beginning with MySQL 5.1.6, it is possible to store the non-indexed columns of NDB tables on disk, rather than in RAM as with previous versions of MySQL Cluster.[More here]

This howto is just a scratch to make it running, for many of you I am suggesting to read some off docs from MySQL page to be prepared to how manage the whole cluster and always know whats going on.

This document comes without warranty of any kind! Bare in mind you need to make tests and prepare your databases before using it in production mode.

http://www.howtoforge.com/setting-up-a-loadbalanced-mysql-cluster-with-mysql5.1

Linux Server Type: Restoring MySQL SimLink. If you’re unable to restart mysqld and troubleshooting the cause:...

Turbo charging MySQL by setting up the query cache

wiredgorilla — Fri, 27 Mar 2009 12:06:06 +0000

To make sure MySQL uses the query cache, there are a few variables you need to set in the configuration file . Usually its my.cnf or my.ini so check on your server with the shell command locate , in our case we are running on a CentOS 5.2 distro and to its my.cnf located in /etc so we opened it by using : nano /etc/my.cnf

First, is the query_cache_type. There are three possible settings: 0 (for off, do not use), 1 (for on, cache queries) and 2 (on demand). To ensure it is always on, place:

query-cache-type = 1

in the configuration file.

The query_cache_type is set to ON now. However, there is one more to set, and that is the query_cache_size. If set to 0 (the default), the cache will be disabled. This variable determines the memory, in bytes, used for the query cache. For our purposes, we will set it to 20 MB:

query-cache-size = 20M

Hope that helped a little

And if you want to check out whats happening in the mySql cache just run this comand

mysql -e “SHOW STATUS LIKE ‘%qcache%’;”

Linux Server Type: Restoring MySQL SimLink. If you’re unable to restart mysqld and troubleshooting the cause:...

Moving mySQL DBs between servers

wiredgorilla — Fri, 27 Mar 2009 12:02:59 +0000

Moving mySQL DBs from one server to another:

mysqldump -uUSER -pPASSWORD txp_database > txp_database.sql

puts the entire thing in one nicely portable text file.

on a new server it takes

mysql -uUSER -pPASSWORD txp_database < txp_database.sql

to import it.

Linux Server Type: Restoring MySQL SimLink. If you’re unable to restart mysqld and troubleshooting the cause:...

Taking backup of mysql database using cron

wiredgorilla — Fri, 27 Mar 2009 11:56:38 +0000

Taking backup of mysql database using cron

Create a file called database_backup.sh and also an empty directory called mysql_backup. The database_backup.sh script should have the following info :

————————————————-
#!/bin/sh

date=`date ‘+%m-%d-%y’`
mysqldump -u database_username -pdatabase_password database_name > ~/mysql_backup/database_name.$date
————————————————-

Run the script that performs the backup job.

————————————————-
* 23 * * * your_userid /path/to/backup/script
————————————————-

Set this script up to run every night, etc. as a cron job. It will save an sql dump of your database every night in the mysql_backup.

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How can I repair corrupt MySQL tables?

wiredgorilla — Fri, 12 Sep 2008 09:37:36 +0000

How can I repair corrupt MySQL tables?

Every so often, MySQL
tables have a way of corrupting themselves. MySQL offers a quick and
painless method of repairing those tables.

cd /usr/local/mysql/var/[DBNAME]/

You will need to replace [DBNAME] with the actual name of your database.

Stop the MySQL server:

/etc/rc.d/init.d/mysql stop

NOTE: Accounts created before July 7th, 2003 will want to use:

/etc/rc.d/init.d/mysqld stop

To check the tables:

myisamchk *.MYI

To repair tables:

myisamchk -r *.MYI

Restart MySQL:

/etc/rc.d/init.d/mysql start

NOTE: Accounts created before July 7th, 2003 will want to use:

/etc/rc.d/init.d/mysqld start

Alternatively, if you do not want to shut down MySQL, you can use mysqlcheck.

mysqlcheck [DBNAME]

To repair the database tables:

mysqlcheck -r [DBNAME]

You will need to replace [DBNAME] with the actual name of your database.

You can find additional documentation here:

http://dev.mysql.com/doc/mysql/en/Table_maintenance.html

http://dev.mysql.com/doc/mysql/en/Using_mysqlcheck.html

Linux Server Type: Restoring MySQL SimLink. If you’re unable to restart mysqld and troubleshooting the cause:...