Question

How to view which transactions are active before commit or rollback?

Answer 1

Using v$transaction
SQL> insert into computer_systems(cs_id) values(1);
SQL> select xidusn, xidsqn from v$transaction;
XIDUSN XIDSQN
---------- ----------
3 12878
SQL> commit;
SQL> select xidusn, xidsqn from v$transaction;
no rows selected