declare
my_exc exception
pragma exception_init(my_exc, -31011)
begin 
select xmltype(t.data, 871)
from ttt  t where  t.doc_format_id = 6 and t.culture_code = 'ru';
exception 
  when others then 
    insert into t_t(f_rowid) values --как тут дальше не пойму

DECLARE
v_rowid rowid;
my_exc exception;
pragma exception_init(my_exc, -31011);
CURSOR cur 
IS 
select *
from  doc_template  t 
where t.doc_format_id = 6 
      and t.culture_code = 'ru';

BEGIN

Open cur;

LOOP

FETCH cur into v_row;

EXIT WHEN cur%NOTFOUND;

select rowid rid, xmltype(v_row.data, 871) xmldata from dual;
EXCEPTION
  when my_exc then
    insert into temp_t(failed_rowid) values(v_row.rowid);

END LOOP;

CLOSE cur;
END;