Hive 2.3 metastore updates/improvements

Hi team, What are the improvements in hive metastore/schematool upgrade from 2.1 -> 2.3? Is there any documentation which provides more information on this? Appreciate your help

select from Hive table results in java.lang.NoClassDefFoundError: javolution/util/FastBitSet

Run-in Fedora 28, hive-0.12.0-5.fc22.noarch hive> select count(*) from customers; Total MapReduce jobs = 1 Launching Job 1 out of 1 Number of reduce tasks determined at compile time: 1 In order to change the average load for a reducer (in bytes): set hive.exec.reducers.bytes.per.reducer= In orde