[20191213]toad 12下BIND_AWARE提示无效.txt

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作者:lfree

[20191213]toad 12下BIND_AWARE提示无效.txt

--//链接http://blog.itpub.net/267265/viewspace-2130781/的测试,发现当时测试的错误.有空再次验证看看.

1.环境:
SCOTT@book> @ ver1
PORT_STRING                    VERSION        BANNER
------------------------------ -------------- --------------------------------------------------------------------------------
x86_64/Linux 2.4.xx            11.2.0.4.0     Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production

create table t as select rownum id ,lpad('x',100,'x') name ,lpad('1',1) flag from dual connect by level<=1e5;
update t set flag='0' where id=1e5;
commit ;
create index i_t_flag on t(flag);

SCOTT@book> execute sys.dbms_stats.gather_table_stats ( OwnName => '',TabName => 't',Estimate_Percent => NULL,Method_Opt => 'FOR ALL COLUMNS SIZE 1 for columns flag size 4',Cascade => True ,No_Invalidate => false)
PL/SQL procedure successfully completed.

2.测试:
--//先写sql语句在toad sql编辑窗口:
select /*+ bind_aware gggg*/ * from t where flag=:x;
--//然后选择执行,代入参数'0'.查询字串gggg,获取sql_id=ddgfa29wynq6d.

SCOTT@book> @ dpc ddgfa29wynq6d outline
PLAN_TABLE_OUTPUT
-------------------------------------
SQL_ID ddgfa29wynq6d, child number 0
-------------------------------------
select /*+ bind_aware gggg*/ * from t where flag=:x
Plan hash value: 1601196873
---------------------------------------------------------------------------
| Id | Operation         | Name | E-Rows |E-Bytes| Cost (%CPU)| E-Time   |
---------------------------------------------------------------------------
|   0 | SELECT STATEMENT |      |        |       |   435 (100)|          |
|* 1 | TABLE ACCESS FULL| T    | 50000 | 5273K|   435   (1)| 00:00:06 |
---------------------------------------------------------------------------
Query Block Name / Object Alias (identified by operation id):
-------------------------------------------------------------
   1 - SEL$1 / T@SEL$1
Outline Data
-------------
/*+
      BEGIN_OUTLINE_DATA
      IGNORE_OPTIM_EMBEDDED_HINTS
      OPTIMIZER_FEATURES_ENABLE('11.2.0.4')
      DB_VERSION('11.2.0.4')
      OPT_PARAM('_optim_peek_user_binds' 'false')
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      ALL_ROWS
      OUTLINE_LEAF(@"SEL$1")
      FULL(@"SEL$1" "T"@"SEL$1")
      END_OUTLINE_DATA
*/
Predicate Information (identified by operation id):
---------------------------------------------------
   1 - filter("FLAG"=:X)

--//注意看下划线,不知道为什么toad要加入修改参数'_optim_peek_user_binds' 'false',不做绑定变量peek,
--//还可以一个细节就是没有获取绑定变量的值.导致提示bind_aware失效.

3.继续测试:
--//取消load cached plan if possible.看到的测试结果也是一样.
--//总之不知道为什么toad 12的版本为什么执行时将会话的_optim_peek_user_binds=false.而导致的提示失效.
--//这个应该在优化与调试sql语句是应该引起注意.
--//另外一个简单的验证就是在sqlplus执行:
SCOTT@book> variable x varchar2(1)
SCOTT@book> exec :x := '0';
PL/SQL procedure successfully completed.

SCOTT@book> @ dpc '' outline
PLAN_TABLE_OUTPUT
-------------------------------------
SQL_ID 8srddvbs5ydfv, child number 0
-------------------------------------
select /*+ bind_aware OPT_PARAM('_optim_peek_user_binds' 'false') */ *
from t where flag=:x
Plan hash value: 1601196873
---------------------------------------------------------------------------
| Id | Operation         | Name | E-Rows |E-Bytes| Cost (%CPU)| E-Time   |
---------------------------------------------------------------------------
|   0 | SELECT STATEMENT |      |        |       |   435 (100)|          |
|* 1 | TABLE ACCESS FULL| T    | 50000 | 5273K|   435   (1)| 00:00:06 |
---------------------------------------------------------------------------
Query Block Name / Object Alias (identified by operation id):
-------------------------------------------------------------
   1 - SEL$1 / T@SEL$1
Outline Data
-------------
/*+
      BEGIN_OUTLINE_DATA
      IGNORE_OPTIM_EMBEDDED_HINTS
      OPTIMIZER_FEATURES_ENABLE('11.2.0.4')
      DB_VERSION('11.2.0.4')
      OPT_PARAM('_optim_peek_user_binds' 'false')
      ALL_ROWS
      OUTLINE_LEAF(@"SEL$1")
      FULL(@"SEL$1" "T"@"SEL$1")
      END_OUTLINE_DATA
*/
Predicate Information (identified by operation id):
---------------------------------------------------
   1 - filter("FLAG"=:X)

--//bind_aware提示无效.
--//如果语句在sqlplus下先执行再在toad下观察呢?
SCOTT@book> select /*+ bind_aware pppp */ * from t where flag=:x;
        ID NAME                                     F
---------- ---------------------------------------- -
    100000 xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx 0
           xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
           xxxxxxxxxxxxxxxxxxxx

SCOTT@book> @ dpc '' ''
PLAN_TABLE_OUTPUT
-------------------------------------
SQL_ID 8b15sjx54pvfw, child number 0
-------------------------------------
select /*+ bind_aware pppp */ * from t where flag=:x

Plan hash value: 120143814

-----------------------------------------------------------------------------------------
| Id | Operation                   | Name     | E-Rows |E-Bytes| Cost (%CPU)| E-Time   |
-----------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |          |        |       |     2 (100)|          |
|   1 | TABLE ACCESS BY INDEX ROWID| T        |      1 |   108 |     2   (0)| 00:00:01 |
|* 2 |   INDEX RANGE SCAN          | I_T_FLAG |      1 |       |     1   (0)| 00:00:01 |
-----------------------------------------------------------------------------------------

--//然后在toad下执行,代入参数'0';

SQL_ID 8b15sjx54pvfw, child number 0
-------------------------------------
select /*+ bind_aware pppp */ * from t where flag=:x

Plan hash value: 120143814

-----------------------------------------------------------------------------------------
| Id | Operation                   | Name     | E-Rows |E-Bytes| Cost (%CPU)| E-Time   |
-----------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |          |        |       |     2 (100)|          |
|   1 | TABLE ACCESS BY INDEX ROWID| T        |      1 |   108 |     2   (0)| 00:00:01 |
|* 2 |   INDEX RANGE SCAN          | I_T_FLAG |      1 |       |     1   (0)| 00:00:01 |
-----------------------------------------------------------------------------------------

Query Block Name / Object Alias (identified by operation id):
-------------------------------------------------------------

   1 - SEL$1 / T@SEL$1
   2 - SEL$1 / T@SEL$1

Outline Data
-------------

/*+
      BEGIN_OUTLINE_DATA
      IGNORE_OPTIM_EMBEDDED_HINTS
      OPTIMIZER_FEATURES_ENABLE('11.2.0.4')
      DB_VERSION('11.2.0.4')
      ALL_ROWS
      OUTLINE_LEAF(@"SEL$1")
      INDEX_RS_ASC(@"SEL$1" "T"@"SEL$1" ("T"."FLAG"))
      END_OUTLINE_DATA
*/

Peeked Binds (identified by position):
--------------------------------------

   1 - (VARCHAR2(30), CSID=852): '0'

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

   2 - access("FLAG"=:X)

Column Projection Information (identified by operation id):
-----------------------------------------------------------

   1 - "T"."ID"[NUMBER,22], "T"."NAME"[VARCHAR2,100], "FLAG"[VARCHAR2,1]
   2 - "T".ROWID[ROWID,10], "FLAG"[VARCHAR2,1]

Note
-----
   - Warning: basic plan statistics not available. These are only collected when:
       * hint 'gather_plan_statistics' is used for the statement or
       * parameter 'statistics_level' is set to 'ALL', at session or system level

SQL_ID 8b15sjx54pvfw, child number 1
-------------------------------------
select /*+ bind_aware pppp */ * from t where flag=:x

Plan hash value: 1601196873

---------------------------------------------------------------------------
| Id | Operation         | Name | E-Rows |E-Bytes| Cost (%CPU)| E-Time   |
---------------------------------------------------------------------------
|   0 | SELECT STATEMENT |      |        |       |   435 (100)|          |
|* 1 | TABLE ACCESS FULL| T    | 50000 | 5273K|   435   (1)| 00:00:06 |
---------------------------------------------------------------------------

Query Block Name / Object Alias (identified by operation id):
-------------------------------------------------------------

   1 - SEL$1 / T@SEL$1

Outline Data
-------------

/*+
      BEGIN_OUTLINE_DATA
      IGNORE_OPTIM_EMBEDDED_HINTS
      OPTIMIZER_FEATURES_ENABLE('11.2.0.4')
      DB_VERSION('11.2.0.4')
      OPT_PARAM('_optim_peek_user_binds' 'false')
      ALL_ROWS
      OUTLINE_LEAF(@"SEL$1")
      FULL(@"SEL$1" "T"@"SEL$1")
      END_OUTLINE_DATA
*/

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

   1 - filter("FLAG"=:X)

Column Projection Information (identified by operation id):
-----------------------------------------------------------

   1 - "T"."ID"[NUMBER,22], "T"."NAME"[VARCHAR2,100], "FLAG"[VARCHAR2,1]

Note
-----
   - Warning: basic plan statistics not available. These are only collected when:
       * hint 'gather_plan_statistics' is used for the statement or
       * parameter 'statistics_level' is set to 'ALL', at session or system level

--//你可以看到生成新的子光标.感觉toad这样设计不好,不利于生产系统调优测试.