Help - how to finde out with a query if table runs in parallel or not?

[PAVB]

Your query is creating a series of "ALTER TABLE..." and "ALTER INDEX..." statements on the fly -those statements will not touch data so no rollback would ever occur.

If you are curious and want to find out tables with parallel option enable just try:

select table_name, degree
from user_tables
where decode(degree, 'DEFAULT', 1, degree) > 1;

Something similar for user_indexes.