That is correct, we are using the functionality similar to HBase. We pull in the HBase BlockCache library with some tweaks to make it work for our scenario. Note that data is never overwritten and HFiles are immutable. So the cache automatically, gets evicted/populated as HFiles are opened and closed. That said, there is a possibility to use more performant formats like rocksdb etc. in the future (the format is pluggable). Or even still use HFiles and have them loaded into some kind of specialized in memory data structure etc.