I would like to share one Problem with you, where Oracle support has just provided standard answer to upgrade to Newer version.
We have Primary 3 Node Rac / standby single instance (non-rac) Physical active data guard in Open read only Mode.
On primary we have 188.8.131.52 with some few latest Patch and Standby is on 184.108.40.206 without any patchset.
The problem is , when we query dynamic tables on standby database ,it does not spikes cpu.But as soon as we Query static or appliation Tables on Standby .It starts spike cpu. even query to static table has sysdba.
the query does not respond and Just hangs. I cant even run AWR / Oradebug.