Interesting node -- but I see a problem brewing with the rows that have 'distance to the next node' > 1. That's data that can be inferred, and if it gets entered wrong, or if someone monkeys with the database, the whole thing comes crashing down.

However, I think I understand what you're doing -- you're trying to pre-cook as much as possible for performance. Thus I'd probably have two tables: the first would have just nearest neighbours, and the second would have all of the inferred data. Then you could use a UNION to get the same performance as your original design.

Just some idle thoughts over my morning coffee.