Mysql notes

Notes on MySQL:

I generally store my MySQL password in an environment variable (like MYSQL_PASSWORD) and then have all of the mysql commands aliased to use the password, e.g.:

 alias mysql="mysql -p$MYSQL_PASSWORD"
 alias mysqladmin="mysqladmin -p$MYSQL_PASSWORD"

However, the modern way to do this is to store in a local defaults file such as:

   % cat defaults.ini
   [client]
   username=myusername
   password=mypassword
   port=myport
   host=myhost

   Then specify this file with:
   MySQL --defaults-extra-file=defaults.ini

Here is a query to size all of the tables:

   SELECT table_schema "DB Name",
      ROUND(SUM(data_length + index_length) / 1024 / 1024, 1) "DB Size in MB" 
   FROM information_schema.tables 
   GROUP BY table_schema; 

Creating a new user for a new database

   MariaDB [(none)]> CREATE DATABASE forensics wiki;
   Query OK, 1 row affected (0.00 sec)
   MariaDB [(none)]> CREATE USER 'fwiki'@'localhost' IDENTIFIED BY 'password';
   Query OK, 0 rows affected (0.09 sec)
   MariaDB [(none)]> GRANT ALL ON forensicswiki.* to 'fwiki'@'localhost';
   Query OK, 0 rows affected (0.06 sec)
   MariaDB [(none)]> FLUSH PRIVILEGES;
   Query OK, 0 rows affected (0.05 sec)
   MariaDB [(none)]> ^D
   Bye

Tuning MySQL

Look at the system load. If mysqld is not consuming 100% of the system load, then it is disk-bound, not CPU bound. You need to increase the buffers.

In the file my.cnf, try editing these values and making them larger until the system is CPU bound:

 key_buffer              = 8192M
 innodb_buffer_pool_size = 1024M
 sort_buffer_size = 100M
 read_buffer_size = 100M
 read_rnd_buffer_size = 100M
 myisam_sort_buffer_size = 100M
 query_cache_size = 1024M

 # Try number of CPU's*2 for thread_concurrency
 thread_concurrency = 8

Try these commands:

 mysql> SHOW INNODB STATUS\G

See also:

• http://www.mysqlperformanceblog.com/2007/11/01/innodb-performance-optimization-basics/
• http://www.mysqlperformanceblog.com/

General

Useful admin commands

 mysqladmin shutdown

Linux

Restart MySQL:

 sudo /etc/init.d/mysql restart