"Access" and "Filter" changes when upgraded to 12c

Team,

we recently upgraded the database from 10.2.0.3 to 12.2.0.1 and - one of the critical sql was running slow.

Upon analysis found - The reason for the slowness is the “Access” and “Filter” Part changes in the explain plan.

When OFE set to 12.2.0.1 – the predicate information shows both Access and Filter – and this sql is running for more than 10 min

BTW – this table has a composite PK with this order C1,C2,C3,C4 – out of all these columns, NDV for C3 column is very high, close to the number of rows in the table, rest other columns (C1,C2,C4) has NDV < 10  and num of rows in this table is around 500M .