If you are trying to debug error ORA-01436: CONNECT BY loop in user data in
the CONNECT BY sql statements, the following might help you:
ALTER SESSION SET "_dump_connect_by_loop_data"=TRUE; -- execute the CONNECT BY here
Now look in the UDUMP destination for the trace file,
it will contain the problematic IDs which are causing the
infinite loop in the hierarchy.
Simply if you want to ignore it, use ‘nocycle’ keyword:
select ... from ... start with somecol = 12345 connect by nocycle prior nodeto_col = nodefrom_col;