Your WordPress database is like a filing cabinet for your website that stores all of your content, including posts, pages, comments, revisions and spam comments, as well as the settings for your themes and plugins. So if you’ve been using WordPress for a while, chances are your database is cluttered and filled with tables you no longer need. This useless data leads to database bloat (I mean, do you really need to save the settings for themes you deleted years ago?), so cleaning up your database not only helps speed up your site so it loads faster, but can also clear up significant space in your database so it runs more efficiently.
With WordPress, there are a few different ways you can tackle optimizing your database. In this post, we’ll look at some mySQL queries you can use to clean up your database in phpMyAdmin as well as some great plugins that make the task even easier.
Note: Before making changes to your database, I highly recommend you backup your website first. Whether you’re making small changes to your site or big ones, having a backup of your site ready to restore will give you peace of mind if something goes wrong.
Optimizing Your WordPress Database with
Source: https://managewp.org/articles/16246/wordpress-database-how-to-make-yours-clean-as-a-whistle
Willie Chiu's Blog 