Unless you are explicitly directed by Hortonworks Support to take a patch update, each of the HDP components should remain at the following package version levels, to ensure a certified and supported copy of HDP 2.6.4. Official Apache versions for HDP 2.6.4: Apache Accumulo 1.7.0. Apache Atlas 0.8.0. read more
One first note: Oryx doesn't necessarily require Hadoop. The model-building element, the Computation Layer, also has a local mode for better scale-down. But yeah the distributed Computation Layer needs Hadoop. read more
** Use of an existing Oracle 12c database is only supported with HDP 2.3 or later. *** Use of an existing PostgreSQL 9.4 is only supported with HDP 2.5 or later. **** Use of an existing MySQL 5.6 database is only supported with the default, InnoDB engine. read more