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硬解析物理读VS软解析逻辑读 测试

原创 Oracle 作者:yuanzai32 时间:2014-01-17 16:38:28 0 删除 编辑
前提:了解硬解析和软解析的定义

硬解析物理读VS软解析逻辑读

这部分比较简单,无须多说,直接看结果
zo_leave@orcl> alter system set events 'immediate trace name flush_cache'; -- 清除缓冲区缓存


系统已更改。


已用时间:  00: 00: 16.44


zo_leave@orcl> alter system flush shared_pool;   -- 清除共享池


系统已更改。


已用时间:  00: 00: 00.73
zo_leave@orcl> set autotrace traceo


zo_leave@orcl> select * from scott.emp where deptno = '10';


已用时间:  00: 00: 00.10


执行计划
----------------------------------------------------------
Plan hash value: 3956160932


--------------------------------------------------------------------------
| Id  | Operation         | Name | Rows  | Bytes | Cost (%CPU)| Time     |
--------------------------------------------------------------------------
|   0 | SELECT STATEMENT  |      |     3 |   261 |     3   (0)| 00:00:01 |
|*  1 |  TABLE ACCESS FULL| EMP  |     3 |   261 |     3   (0)| 00:00:01 |
--------------------------------------------------------------------------


Predicate Information (identified by operation id):
---------------------------------------------------


   1 - filter("DEPTNO"=10)


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




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


-- 仅清空清除缓冲区缓存
zo_leave@orcl> set autotrace off
zo_leave@orcl> alter system set events 'immediate trace name flush_cache';


系统已更改。


已用时间:  00: 00: 10.56
zo_leave@orcl> set autotrace traceo
zo_leave@orcl> select * from scott.emp where deptno = '10';


已用时间:  00: 00: 00.03


执行计划
----------------------------------------------------------
Plan hash value: 3956160932


--------------------------------------------------------------------------
| Id  | Operation         | Name | Rows  | Bytes | Cost (%CPU)| Time     |
--------------------------------------------------------------------------
|   0 | SELECT STATEMENT  |      |     3 |   261 |     3   (0)| 00:00:01 |
|*  1 |  TABLE ACCESS FULL| EMP  |     3 |   261 |     3   (0)| 00:00:01 |
--------------------------------------------------------------------------


Predicate Information (identified by operation id):
---------------------------------------------------


   1 - filter("DEPTNO"=10)


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
        943  bytes sent via SQL*Net to client
        416  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          3  rows processed


-- 不做任何处理
zo_leave@orcl> select * from scott.emp where deptno = '10';


已用时间:  00: 00: 00.00


执行计划
----------------------------------------------------------
Plan hash value: 3956160932


--------------------------------------------------------------------------
| Id  | Operation         | Name | Rows  | Bytes | Cost (%CPU)| Time     |
--------------------------------------------------------------------------
|   0 | SELECT STATEMENT  |      |     3 |   261 |     3   (0)| 00:00:01 |
|*  1 |  TABLE ACCESS FULL| EMP  |     3 |   261 |     3   (0)| 00:00:01 |
--------------------------------------------------------------------------


Predicate Information (identified by operation id):
---------------------------------------------------


   1 - filter("DEPTNO"=10)


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




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




 


来自 “ ITPUB博客 ” ,链接:http://blog.itpub.net/26477854/viewspace-1072247/,如需转载,请注明出处,否则将追究法律责任。

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