WordPress database stores all data what is necessary for your website. Unfortunately time to time there will be generated some unnecessary data, which can use space and can slow down database operations.
Database Optimizer cleans up database tables and can fix data fragmentation. You can also set up timed tasks to keep your database clean.
It is always necessary to make a backup before you touch anything in Database Optimizer – better safe than sorry.
General
Reindex & Optimize Tables
Reindex (and Optimize) tables will rebuilds the tables to update indexes statistics and free unused space in the clustered index.
Expired Transients
WordPress is using transients to store temporary data. These transients has an expiration time, however sometimes they won’t be deleted when they expired. You can here delete manually already expired entries from options table.
Autoload size
If Autoload size is too big, you may need to clean up wp_options table manually to decrease memory usage.
Posts
Revisions & Trashed posts
Revisions and Trashed posts are really helpful when you are editing posts to be able to restore a previous version of the post. However when you finished and you don’t need them anymore, you can delete them to decrease DB size.
Orphan- metadata and attachments
Every WordPress posts have metadata and some of them have attachments as well. If posts were deleted improperly, you may need to delete orphan metadata and attachments manually.
Duplicated postmeta
Some badly coded themes and plugins can store duplicated meta for posts. Be careful with this, because some plugins (like WooCommerce) use duplicated meta for reason.
Comments
Spam & Trashed comments
Most WordPress websites are suffering from spam comments. You can delete spam and trashed comments here at once.
Orphan commentmeta
Every WordPress comments can have metadata. If some comments were deleted improperly, you may need to delete orphan metadata manually
Duplicated commentmeta
Some badly coded themes and plugins can store duplicated meta for comments as well. With this feature you can delete them easily.
Terms & Users
Orphan term- and usermeta
Every WordPress terms and users can have metadata. If some comments or users were deleted improperly, you may need to delete orphan metadata manually
Duplicated usermeta
Some badly coded themes and plugins can store duplicated meta for users as well. With this feature you can delete them easily.