When start a new WordPress site, your database won’t have too much bloat. As you install plugins and add new content, your database will fill up and gets filled with orphaned post, comment, and user data. You can always write your own SQL commands to clean up your database. WP-Sweep simply makes the job easier.
WP-Sweep cleans up revisions, deleted comments, orphaned meta data, duplicated meta, unused terms, transients, and everything in between. The plugin uses standard WordPress functions instead of MySQL queries.
WP-Sweep should be safe on most sites but you should still have a recent backup of your database just to be on the safe side.