Disable SQL plan directives—For Oracle Database 12.1 only
For improved performance, make sure that there are no SQL plan directives, or that all directives are disabled.
To display all existing SQL plan directives, run the following SQL*Plus commands:
SELECT distinct d.directive_id AS did
FROM dba_sql_plan_directives d
JOIN dba_sql_plan_dir_objects o
ON (d.directive_id=o.directive_id)