[joshmn]

Not an admin, so I can't speak to what they have available. But as a hacker...

Since the usernames are not queryable via an integer (e.g. user?id=1235654321) it's not exactly the most trivial of things. You'd have to go through an endless amount of posts, get every possible username from the comments, go through all stories submitted, grab their usernames, and then loop through the HN API and grab karma info.

[S4M]

    select sum(karma) from user_data;

If the HN server uses an SQL database and has a table users containing the user names and their karma - and they must have something like that since the karmas are displayed on the profiles.

[krapp]

Flat files and Lisp macros, with everything stored as closures in RAM, AFAIK. HN doesn't use a relational database at all[0], unless they added one recently.

[0] http://arclanguage.org/