Please don't post in the Alpha/Beta forum unless you're actually testing the alpha/beta version of WordPress (not a plugin or a theme). Also, once WordPress has released a version, it's not appropriate to post in alpha/beta and you should post in the How To & Troublshooting forum:
https://wordpress.org/support/forum/how-to-and-troubleshooting
This post has been moved out for you.
Answer: comment_karma is used by Akismet and other plugins to track and manage your comments. It's not used by core WP, just a lot of plugins, so we leave it alone. If you're coding a way to track user behavior in comments, use that :)