I think an important question for this is how many users are we talking about? If it's sufficiently small, I think the question to ask is "Do I need to pregenerated the ladder, or have it dynamically built as needed?".

If your ladder is simply a ranking of people based on a simple equation (ie, "score" as in your example, a single value) then generating a 50 rung ladder could be as simple as

   select id,score from table order by score desc limit 50;
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in SQL which would return a list of the top 50 rung members. Implementation via DBI I'll leave to the reader.

Even if the equation is complex, it still may be doable on-the-fly using joins, math functions, and other features of SQL.

But this method may not be fast enough if your database is of sufficient size. It's a balancing act.