SQL & PL/SQL

Hi,

I have two tables one is parent and other is child.

ORDER_PRNT (Order_id (pk), Order_desc, create_date);

ORDER_CHILD (Order_id (fk), item)

this is just sample tables and columns as i cannot put actual table names here.

two talbles are containing huge data, i have to delete records older than 10 days daily. so i am doing this operations:

1. delete from child table first:

DELETE FROM ORDER_CHILD where Order_id in (select order_id from ORDER_PRNT where create_Date<sysdate-10);

2. delete from parent table :

DELETE FROM ORDER_PRNT where create_Date<sysdate-10;

The question is regarding better performance. If we can put "on delete cascade" condition for FK then i need not to write 1st delete statement right?
So oracle will automatically deletes the records of child whenever parent record is deleted.

So tell me which one is faster here?

shall i put ondelete cascade to FK ?
or
Manually delete from child table ?


Please suggest.

Thanks.