Regarding use case of epoch to generate nanoseconds precision

Hi

Postgres supports only upto microseconds (6 decimal precision).
How do we generate timestamp with nanoseconds as rds postgres not
supported timestamp9 extension ?
Is there a way to generate timestamp with nanoseconds precision on
pg_partman with epoch without typecasting or with typecasting ?

p_epoch => (to_timestamp(control column))
Here what is the control column?
How to run it with the create_parent function of partman?

Here as per the pg_partman doc
p_epoch - tells pg_partman that the control column is an integer type, but
actually represents an epoch time value. Valid values for this option are:
'seconds', 'milliseconds', 'nanoseconds', and 'none'. The default is
'none'. All table names will be time-based. In addition to a normal index
on the control column, be sure you create a functional, time-based index on
the control column (to_timestamp(control column)) as well so this works
efficiently.

Regards,
Durga Mahesh Manne