create table demo 
partition by list (object_type) 
subpartition by list (owner) 
subpartition template 
( 
 subpartition sp1   values ('SYS') 
,subpartition spdef values (DEFAULT) 
)  
(  
 partition p1   values ('TABLE') 
,partition p2   values ('INDEX') 
,partition p3   values ('SYNONYM') 
,partition pdef values (DEFAULT) 
) 
as select owner, object_type, object_name from all_objects;

CREATE OR REPLACE TRIGGER TRIGGER1  
BEFORE UPDATE ON DEMO FOR EACH ROW  
BEGIN 
  :NEW.object_name := lower(:new.OBJECT_NAME); 
END; 
/

select count(*) from demo;

COUNT(*)  
73823  

select count(*) from demo
where  object_name = lower(object_name);

COUNT(*)  
1187  

declare
  l_sql_stmt varchar2(1000);
  l_try number;
  l_status number;
begin
 
  -- create the task
  dbms_parallel_execute.create_task ('mytask');
 
  -- chunk the table by rowid
  dbms_parallel_execute.create_chunks_by_rowid('mytask', user, 'DEMO', true, 1000);
 
  -- execute the dml in parallel
  l_sql_stmt := 'update demo set object_name = object_name || ''#'' 
      where rowid between :start_id and :end_id';
  dbms_parallel_execute.run_task('mytask', l_sql_stmt, dbms_sql.native,
                                 parallel_level => 4);
  
  dbms_output.put_line(DBMS_PARALLEL_EXECUTE.TASK_STATUS('mytask'));
  -- done with processing; drop the task
  dbms_parallel_execute.drop_task('mytask');
   
end;
/

select count(*) from demo
where  object_name = lower(object_name);

COUNT(*)  
73823