Cache affect In oracle

>sqlplus hr/hr@xe

SQL*Plus: Release 10.2.0.1.0 - Production on ...

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Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options

SQL> set autotrace traceonly statistics;

SQL> alter system flush shared_pool;

System altered.

SQL> alter system flush buffer_cache;

System altered.

SQL> select count(*) from table_a where column_a = 1;--first call


Statistics
----------------------------------------------------------
       2224  recursive calls
          0  db block gets
        638  consistent gets
         49  physical reads
          0  redo size
        335  bytes sent via SQL*Net to client
        376  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
         57  sorts (memory)
          0  sorts (disk)
          1  rows processed

SQL> select count(*) from table_a where column_a = 1; --second call, cache affect


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

SQL>