The following command will optimize all of your databases' tables within MySQL.
It is important to optimize tables to reduce data fragmentation.

mysqlcheck -Aop -uroot

If you are not using root replace it with your username.

-A : Check all tables in all databases. This is the same as using the --databases option and naming all the databases on the command line.
-o : optimize the tables.
-p : Prompts for a password to use when connecting to the MySQL server.
-u : The MySQL user name to use when connecting to the server.

Inspired by this article.