Here’s a previous answer about hash function that you might find useful: https://groups.google.com/forum/#!topic/couchbase/_RNYi2_kyNA
Basically we don’t recommend changing it, unless you really really really know what you are doing.
That being said, if you want to do something like a sequential read, you could probably buffer small doc on the client side and then write them as one doc every minute for instance. This can work well for time-series. Can you describe your use case a bit more?