Nice, here's an attempt to compute the HN-index for all users. (Differs from blog post; not sure if because the data from the two sources is different, or there's a mistake somewhere):

    WITH Ranking AS (
        SELECT 
            by,
            score,
            RANK () OVER (PARTITION BY by ORDER BY score DESC) AS rank
        FROM hackernews_history
    )
    SELECT by, MIN(rank - 1) as h_index
    FROM Ranking
    WHERE rank > score
    GROUP BY by
    ORDER BY h_index DESC
    LIMIT 100