WP Speed of Light: Database Cleanup
There are 6 tools to clean up the WordPress database.
Clean all post revisions: WordPress, by default, is generating content revisions (copy) to restore it from an old version. If you don’t need revisions, clean up!
Clean all auto drafted content: WordPress, by default, have an auto-saving feature to restore content from the latest auto-saved version. If you don’t need auto-saved content, clean up!
Remove all trashed content: All content (post, page,...) in the trash will be cleaned up.
Remove comments from trash & spam: All comments in the trash or classified as spam will be cleaned up
Remove trackbacks and pingbacks: These are methods for alerting blogs that you have linked to them. If you don’t need revision, clean up!
Remove transient options: Transient is something like a basic cache system used by WordPress. No risk it’s regenerated by WordPress automatically.
PRO ADDON ONLY
Automatic cleanup: Active the database automatic cleanup
Cleanup each: Define automatic cleanup frequency
Duplicated post meta: Remove duplicated post meta from the database
Duplicated comment meta: Remove duplicated comment meta from the database
Duplicated user meta: Remove duplicated user meta from the database
Duplicated term meta: Remove duplicated term meta from the database
Optimize database tables: You can use OPTIMIZE TABLE to reclaim the unused space and to defragment the data file.