Categories
Database Server

Regularly Runs MySQL FLUSH QUERY CACHE

In some situation, like suggested in some mysql optimization script, you may want to regularly run “FLUSH QUERY CACHE”.

First, open your terminal and try to run this command :

mysql -e 'FLUSH QUERY CACHE'

If there is no error, you can add that command in your cron job, such as this command to run it every 10 minutes :

*/10 * * * * mysql -e 'FLUSH QUERY CACHE'
Categories
Database

Setting MySQL innodb_buffer_pool_size

I was confused how big i should set my “innodb_buffer_pool_size” value.

Then i find this post in stackexchange.

I can run this query to get what is the suggestion of “innodb_buffer_pool_size” value.

SELECT CEILING(Total_InnoDB_Bytes*1.6/POWER(1024,3)) RIBPS FROM
(SELECT SUM(data_length+index_length) Total_InnoDB_Bytes
FROM information_schema.tables WHERE engine='InnoDB') A;

The result will be in GB.

Categories
Database Server

Exporting MySQL Databases Command Line in Linux

To export a mysql database by linux command line,
for example your database name is my_database, your mysql username is my_username, and your mysql password is my_password, you can use this command :

mysqldump --opt --single-transaction -umy_username -pmy_password my_database > /your/path/here/export.sql

Note: after “-u” and “-p”, there is NO space. 🙂

Categories
Database Server

MySQL Table “In Use” Repair

Recently when i optimized some mysql tables from phpmyadmin, some of the tables were “locked” and showed as “in use” on phpmyadmin. The tables could not be used, read, etc. So the script was stopped working.
I have tried to repair / check / analyze from phpmyadmin but i couldn’t repair it.
So i tried to repair the mysql tables from SSH.

Go to your database directory. Usually it is located on
/etc/var/lib/mysql/YOUR_DATABASE_NAME/

So use this command first
cd /etc/var/lib/mysql/YOUR_DATABASE_NAME/

Next, use this command
myisamchk --safe-recover --force YOUR_TABLE_NAME

And the MySQL table should be repaired now.

Categories
PHP Programming

Multilanguage Programming with UTF-8 Encoding

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Multilanguage non-ASCII site? Sometimes we need to make website that can handle languages which contains non-ASCII characters, for example chinese, russian, french, germany, etc.
To handle this, we need to handle the language on 3 parts : on PHP itself, HTML, and on the database (i use MySQL as example here).
Basically, we need to adjust the charset (character set) into UTF-8.