Oracle - SQL - MySQL DBA - Life Long Learning Experience

On one of our Cloud Environment we encountered Performance deteriorating .  Initial checks stated High CPU  utilization oracle process consuming 100 % of one CPU  out of 4 . Underlying sql is the stats gathering which is being run on an continual basis . As we looked at the partitions of that segment (WRI$_OPTSTAT_SYNOPSIS$) , which has total partitions of 8384 .  From  longops  the queery which was being run was : SELECT DISTINCT BO#, GROUP# FROM SYS.WRI$_OPTSTAT_SYNOPSIS_HEAD$ H WHERE GROUP# <> 0 AND GROUP# NOT IN (SELECT T.OBJ# * 2 FROM S YS.TABPART$ T UNION ALL SELECT T.OBJ# * 2 FROM SYS.TABCOMPART$ T )  On Engaging oracle we found the Bug which existed in 12.1.0.2  was  Bug 19450139 - Slow gather table stats with incremental stats enabled ( Doc ID 19450139.8 )   Since we had Proactive BP applied 12.1.0.2.171017 , we then downloaded the patch for release "DATABASE BP 12.1.0.2.171017" --  p19450139_12102171017ProactiveBP_Linux-x86-64.zip

It wasn't right I thought, when i saw logs were not shipping to the standby site . This was after i configured physical standby dataguard using Duplicate method . Below are are the steps taken to diagnose the issue.   After setting the parameter right and re-enabling the state everything went fine which you could look at the error state for the destination which says "VALID"  .   O/p in the alert log was  completely satisfying .