HDFS caching helps, however it helps only a bit since you are saving only the cost of moving bytes off disk and are still paying the cost of de-serialization, don't get JVM JIT etc. So, with technologies like Hive LLAP (coming in hive-2) you will get significantly better performance because LLAP caches de-serialized vectors in memory-efficient formats (2 bits for certain integer ranges - rather than 4 bytes), cpu-efficient filters (vectorized query processing via filters etc.) removes JVM startup cost for tasks (100s of ms), provides JIT-enhanced CPU performance etc. Rather excited about it! ... View more