When I was learning about the secondary index in Cassandra, I've found the mention of special Cassandra's algorithm used to range and secondary index queries. After some time passed on exploring secondary index mechanism, it's a good moment to discover the algorithm making it work.
The data organization in key-value oriented NoSQL databases is very often based on a pair of keys: partition and sorting. However they also offer other feature called secondary index that can be a good alternative to previously described index table pattern.
