SQL> set autot traceonly stat

--Flusshing the Buffer cache so there will be no traces from the last test.
SQL> alter system flush buffer_cache;
System altered.


SQL> select /*+ cache */ sum(num1) from pmds.tab1;
Statistics
----------------------------------------------------------
          0  recursive calls
          0  db block gets
       6019  consistent gets
       6015  physical reads				 <----------   
          0  redo size
        532  bytes sent via SQL*Net to client
        523  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          1  rows processed

SQL> /
Statistics
----------------------------------------------------------
          0  recursive calls
          0  db block gets
       6019  consistent gets
       6010  physical reads				 <----------   
          0  redo size
        532  bytes sent via SQL*Net to client
        523  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          1  rows processed

SQL> /
Statistics
----------------------------------------------------------
          0  recursive calls
          0  db block gets
       6019  consistent gets
       6010  physical reads				 <----------   
          0  redo size
        532  bytes sent via SQL*Net to client
        523  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          1  rows processed


--Setting the Event in the session level

SQL> alter session set events '10949 trace name context forever, level 1';
Session altered.

--The first execution will perform Physical reads
SQL> select /*+ cache */ sum(num1) from pmds.tab1;
Statistics
----------------------------------------------------------
          0  recursive calls
          0  db block gets
       6024  consistent gets
       6010  physical reads				 <----------   
          0  redo size
        532  bytes sent via SQL*Net to client
        523  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          1  rows processed

		  
--From the second run, there are no Physical reads.		  
SQL> /
Statistics
----------------------------------------------------------
          0  recursive calls
          0  db block gets
       6024  consistent gets
          0  physical reads				 <----------   
          0  redo size
        532  bytes sent via SQL*Net to client
        523  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          1  rows processed

SQL> /
Statistics
----------------------------------------------------------
          0  recursive calls
          0  db block gets
       6024  consistent gets
          0  physical reads				 <----------   
          0  redo size
        532  bytes sent via SQL*Net to client
        523  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          1  rows processed