It is natural for a database to increase in size with time. When you add new content or allow visitors to take various actions on the website - such as commenting - new information is stored in the database, making it grow in size. Most CMS like Wordpress has the public commenting feature turned on by default, even though you might not need it. In some cases, spammers take advantage of this feature, creating and posting many spam messages, taking up the database's space.

On other occasion, a technical issue with the website can also cause the database to grow in size. For example, plugins with bug or some custom modules may generate a lot of wasted log and key-data in the database.

To keep your MySQL database optimized and small, it is advisable to:

• Perform regular maintenance checks for plugin updates and for the size of your database.
• Vacuum the database from time to time, which helps to reduce the disk usage.
• Disable unused plugin or feature (e.g. the commenting feature).
• Employ Captcha to reduce spamming through forms and comments.
• Do not store log in your database.