分区表带partition参数和where性能比较

不知道是个别现象，还是就是这样，结果还不敢确认
SQL> select * from awen.awen_date where birth<to_date('19900101','yyyymmdd');


执行计划
----------------------------------------------------------
Plan hash value: 2794993436

--------------------------------------------------------------------------------

--------------------

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time
| Pstart| Pstop |

--------------------------------------------------------------------------------

--------------------

| 0 | SELECT STATEMENT | | 2 | 44 | 9 (0)| 00:00:

01 | | |

| 1 | PARTITION RANGE SINGLE| | 2 | 44 | 9 (0)| 00:00:

01 | 1 | 1 |

| 2 | TABLE ACCESS FULL | AWEN_DATE | 2 | 44 | 9 (0)| 00:00:

01 | 1 | 1 |

--------------------------------------------------------------------------------

--------------------


Note
-----
- dynamic sampling used for this statement


统计信息
----------------------------------------------------------
0 recursive calls
0 db block gets
8 consistent gets
6 physical reads
0 redo size
512 bytes sent via SQL*Net to client
385 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
2 rows processed

SQL> alter system flush buffer_cache;

系统已更改。

SQL> select * from awen.awen_date partition(part_1);


执行计划
----------------------------------------------------------
Plan hash value: 2794993436

--------------------------------------------------------------------------------

--------------------

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time
| Pstart| Pstop |

--------------------------------------------------------------------------------

--------------------

| 0 | SELECT STATEMENT | | 2 | 44 | 9 (0)| 00:00:

01 | | |

| 1 | PARTITION RANGE SINGLE| | 2 | 44 | 9 (0)| 00:00:

01 | 1 | 1 |

| 2 | TABLE ACCESS FULL | AWEN_DATE | 2 | 44 | 9 (0)| 00:00:

01 | 1 | 1 |

--------------------------------------------------------------------------------

--------------------


Note
-----
- dynamic sampling used for this statement


统计信息
----------------------------------------------------------
5 recursive calls
0 db block gets
16 consistent gets
6 physical reads
0 redo size
512 bytes sent via SQL*Net to client
385 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
2 rows processed

加partition后 出现了recursive calls 且consistent gets也要多