SQL> set autotrace on statistics
SQL> set timing on
<again, third run>
SQL> SELECT o.owner, o.object_type, COUNT(*)
  2  FROM all_my_objects o
  3  GROUP BY CUBE (o.object_type, o.owner);

OWNER                          OBJECT_TYPE           COUNT(*)                   
------------------------------ ------------------- ----------                   
<output snipped>

327 rows selected.

Elapsed: 00:00:13.46

Statistics
----------------------------------------------------------                      
          0  recursive calls                                                    
          0  db block gets                                                      
      11002  consistent gets                                                    
       6025  physical reads                                                     
          0  redo size                                                          
       8198  bytes sent via SQL*Net to client                                   
        651  bytes received via SQL*Net from client                             
         23  SQL*Net roundtrips to/from client                                  
          2  sorts (memory)                                                     
          0  sorts (disk)                                                       
        327  rows processed