SQL> select /*+rule*/COUNT(*) from v_$temp_extent_pool t;
 
  COUNT(*)
----------
         0
 
SQL> select COUNT(*) from v_$temp_extent_pool t;
 
  COUNT(*)
----------
         1
 
SQL> 

SQL> select count(*) from (
  2    select 
  3          h.ksmchds,h.ksmchcom ksmchnam,h.ksmchsiz,h.ksmchcls,h.ksmchpar 
  4    from  x$ksmhp h, x$ksmsp s
  5    where h.ksmchds=s.ksmchpar and s.ksmchcom='library cache'
  6  );

  COUNT(*)
----------
         0

SQL> select count(*) from (
  2    select /*+ use_nl(патамуштахачуштонибутьпалучить)*/
  3          h.ksmchds,h.ksmchcom ksmchnam,h.ksmchsiz,h.ksmchcls,h.ksmchpar 
  4    from  x$ksmhp h, x$ksmsp s
  5    where h.ksmchds=s.ksmchpar and s.ksmchcom='library cache'
  6  );

  COUNT(*)
----------
     11263

SQL>