固定执行计划-使用SPM(Sql Plan Management)固定执行计划

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标题:固定执行计划-使用SPM(Sql Plan Management)固定执行计划

作者:Lunar©版权所有[文章允许转载,但必须以链接方式注明源地址,否则追究法律责任.]

测试目的: 使用SPM(Sql Plan Management)固定执行计划和hint中指定no index,谁的优先级高?
.
固定执行计划-使用SQL Tuning Advisor
固定执行计划-手工指定PLAN OUTLINE
固定执行计划-手工指定索引名称的方式
固定执行计划-使用coe_xfr_sql_profile固定执行计划
固定执行计划-使用SPM(Sql Plan Management)固定执行计划
.

在Oracle 11g前,我们可以借助存储大纲(Stored Outline)和SQL Profile来帮助我们固定某个SQL语句的执行计划。
11g中,Oracle 提供了SPM(Sql Plan Management)。
通过这个特性,可以考虑让Oracle自动去判断某个SQL的新的执行计划是否更加合理(成本更低),只有在新的执行计划比原来的执行计划更好才会被使用,从而保护了执行计划的稳定性和SQL语句的执行效率。
可以考虑手工捕获和自动捕获两种方式,这里我们采用手工捕获(11.2的缺省设置是非自动捕获)。
首先查看当前为禁止自动捕获的状态:

SYS@lunardb>show parameter optimizer_capture_sql_plan_baselines

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
optimizer_capture_sql_plan_baselines boolean     FALSE
SYS@lunardb>

当前SPM中没有内容:

LUNAR@lunardb>select signature,sql_handle,plan_name,origin,enabled,accepted,autopurge from dba_sql_plan_baselines;

no rows selected

Elapsed: 00:00:00.00
LUNAR@lunardb>

手工加载一个SQL到SPM中:

LUNAR@lunardb>declare
  2    l_plans_loaded  PLS_INTEGER;
  3  begin
  4    l_plans_loaded := DBMS_SPM.load_plans_from_cursor_cache(sql_id => '&sql_id');
  5    DBMS_OUTPUT.put_line('Plans Loaded: ' || l_plans_loaded);
  6  END;
  7  /
Enter value for sql_id: bjgduva68mbqm
old   4:   l_plans_loaded := DBMS_SPM.load_plans_from_cursor_cache(sql_id => '&sql_id');
new   4:   l_plans_loaded := DBMS_SPM.load_plans_from_cursor_cache(sql_id => 'bjgduva68mbqm');
Plans Loaded: 1

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.21
LUNAR@lunardb>
LUNAR@lunardb>select signature,sql_handle,plan_name,origin,enabled,accepted,autopurge from dba_sql_plan_baselines;

       SIGNATURE SQL_HANDLE                     PLAN_NAME                      ORIGIN         ENA ACC AUT
---------------- ------------------------------ ------------------------------ -------------- --- --- ---
6.5941520220E+17 SQL_0926b6a1f69f6f5c           SQL_PLAN_0k9pqn7v9yvuw02b73393 MANUAL-LOAD    YES YES YES

Elapsed: 00:00:00.01
LUNAR@lunardb>

由于上一个测试,我们已经有了正确的执行计划,即:

LUNAR@lunardb>select * from table(dbms_xplan.display_cursor(sql_id=>'bjgduva68mbqm')) where plan_table_output  like ('Plan hash value%');

PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Plan hash value: 3241900148

Elapsed: 00:00:00.02
LUNAR@lunardb>
LUNAR@lunardb>select SQL_HANDLE, PLAN_NAME, ENABLED, ACCEPTED, SQL_TEXT 
  2  from DBA_SQL_PLAN_BASELINES 
  3  where ACCEPTED = 'YES'
  4  order by LAST_MODIFIED;

SQL_HANDLE                     PLAN_NAME                      ENA ACC SQL_TEXT
------------------------------ ------------------------------ --- --- --------------------------------------------------------------------------------
SQL_0926b6a1f69f6f5c           SQL_PLAN_0k9pqn7v9yvuw02b73393 YES YES select /*+ no_index(lunartest1 idx_lunartest1_n) */ * from lunartest1 where n=1

Elapsed: 00:00:00.01
LUNAR@lunardb>

下面,我们装载指定的执行计划:

LUNAR@lunardb>variable cnt number ;
LUNAR@lunardb>exec :cnt :=dbms_spm.LOAD_PLANS_FROM_CURSOR_CACHE (SQL_ID => '&SQL_ID',PLAN_HASH_VALUE => &plan_hash_value, SQL_HANDLE => '&SQL_HANDLE' ) ; 
Enter value for sql_id: bjgduva68mbqm
Enter value for plan_hash_value: 1172089107
Enter value for sql_handle: SQL_0926b6a1f69f6f5c

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.02
LUNAR@lunardb>select signature,sql_handle,plan_name,origin,enabled,accepted,autopurge 
  2  from dba_sql_plan_baselines where CREATED>sysdate-1/48 order by created;

             SIGNATURE SQL_HANDLE                     PLAN_NAME                      ORIGIN         ENA ACC AUT
---------------------- ------------------------------ ------------------------------ -------------- --- --- ---
    659415202199990108 SQL_0926b6a1f69f6f5c           SQL_PLAN_0k9pqn7v9yvuw02b73393 MANUAL-LOAD    YES YES YES

Elapsed: 00:00:00.00
LUNAR@lunardb>

确认该执行计划的OUTLINE:

LUNAR@lunardb>SELECT extractValue(value(h),'.') AS hint
  2  FROM sys.sqlobj$data od, sys.sqlobj$ so,
  3  table(xmlsequence(extract(xmltype(od.comp_data),'/outline_data/hint'))) h
  4  WHERE so.name = 'SQL_PLAN_0k9pqn7v9yvuw02b73393'
  5  AND so.signature = od.signature
  6  AND so.category = od.category
  7  AND so.obj_type = od.obj_type
  8  AND so.plan_id = od.plan_id;

HINT
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
IGNORE_OPTIM_EMBEDDED_HINTS
OPTIMIZER_FEATURES_ENABLE('11.2.0.4')
DB_VERSION('11.2.0.4')
ALL_ROWS
OUTLINE_LEAF(@"SEL$1")
INDEX(@"SEL$1" "LUNARTEST1"@"SEL$1" ("LUNARTEST1"."N"))

6 rows selected.

Elapsed: 00:00:00.08
LUNAR@lunardb>

这里看到是我们需要的走索引的outline,详细的OUTLINE信息如下:

LUNAR@lunardb>SELECT extractValue(value(h),'.') AS hint
  2  FROM sys.sqlobj$data od, sys.sqlobj$ so,
  3  table(xmlsequence(extract(xmltype(od.comp_data),'/outline_data/hint'))) h
  4  WHERE so.signature = '659415202199990108'
  5  AND so.signature = od.signature
  6  AND so.category = od.category
  7  AND so.obj_type = od.obj_type
  8  AND so.plan_id = od.plan_id;

HINT
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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(@"SEL$1" "LUNARTEST1"@"SEL$1" ("LUNARTEST1"."N"))
END_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(@"SEL$1" "LUNARTEST1"@"SEL$1" ("LUNARTEST1"."N"))

14 rows selected.

Elapsed: 00:00:00.10
LUNAR@lunardb>    

现在我们删除profile以前用coe绑定的sql profile:

LUNAR@lunardb>SELECT * FROM DBA_SQL_PROFILES;

NAME                           CATEGORY                                    SIGNATURE SQL_TEXT
------------------------------ ------------------------------ ---------------------- --------------------------------------------------------------------------------
CREATED                                                                     LAST_MODIFIED
--------------------------------------------------------------------------- ---------------------------------------------------------------------------
DESCRIPTION
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
TYPE    STATUS   FOR          TASK_ID TASK_EXEC_NAME                      TASK_OBJ_ID      TASK_FND_ID      TASK_REC_ID
------- -------- --- ---------------- ------------------------------ ---------------- ---------------- ----------------
coe_bjgduva68mbqm_3241900148   DEFAULT                            659415202199990108 select /*+ no_index(lunartest1 idx_lunartest1_n) */ * from lunartest1 where n=1
12-JAN-16 11.24.18.000000 AM                                                12-JAN-16 11.40.52.000000 AM
coe bjgduva68mbqm 3241900148 659415202199990108 9900816299026594015
MANUAL  ENABLED  NO


Elapsed: 00:00:00.01
LUNAR@lunardb>
LUNAR@lunardb>exec dbms_sqltune.drop_sql_profile('coe_bjgduva68mbqm_3241900148'); 

PL/SQL procedure successfully completed.

Elapsed: 00:00:00.01
LUNAR@lunardb>SELECT * FROM DBA_SQL_PROFILES;

no rows selected

Elapsed: 00:00:00.00
LUNAR@lunardb>

再次验证SPM的执行计划:

LUNAR@lunardb>select * from table(dbms_xplan.DISPLAY_SQL_PLAN_BASELINE('&sql_handle','&PLAN_NAME'));
Enter value for sql_handle: SQL_0926b6a1f69f6f5c
Enter value for plan_name: SQL_PLAN_0k9pqn7v9yvuw02b73393
old   1: select * from table(dbms_xplan.DISPLAY_SQL_PLAN_BASELINE('&sql_handle','&PLAN_NAME'))
new   1: select * from table(dbms_xplan.DISPLAY_SQL_PLAN_BASELINE('SQL_0926b6a1f69f6f5c','SQL_PLAN_0k9pqn7v9yvuw02b73393'))

PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------
SQL handle: SQL_0926b6a1f69f6f5c
SQL text: select /*+ no_index(lunartest1 idx_lunartest1_n) */ * from lunartest1
          where n=1
--------------------------------------------------------------------------------

--------------------------------------------------------------------------------
Plan name: SQL_PLAN_0k9pqn7v9yvuw02b73393         Plan id: 45560723
Enabled: YES     Fixed: NO      Accepted: YES     Origin: MANUAL-LOAD
--------------------------------------------------------------------------------

Plan hash value: 3241900148

-------------------------------------------------------------------------------------
| Id  | Operation        | Name             | Rows  | Bytes | Cost (%CPU)| Time     |
-------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT |                  |     1 |     4 |     1   (0)| 00:00:01 |
|*  1 |  INDEX RANGE SCAN| IDX_LUNARTEST1_N |     1 |     4 |     1   (0)| 00:00:01 |
-------------------------------------------------------------------------------------

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

   1 - access("N"=1)

25 rows selected.

Elapsed: 00:00:00.16
LUNAR@lunardb>

执行SQL,发现SPM可以固定执行计划,使用了我们期待的:

LUNAR@lunardb>set autotrace traceo exp stat
LUNAR@lunardb>select /*+ no_index(lunartest1 idx_lunartest1_n) */ * from lunartest1 where n=1;

Elapsed: 00:00:00.13

Execution Plan
----------------------------------------------------------
Plan hash value: 3241900148

-------------------------------------------------------------------------------------
| Id  | Operation        | Name             | Rows  | Bytes | Cost (%CPU)| Time     |
-------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT |                  |     1 |     4 |     1   (0)| 00:00:01 |
|*  1 |  INDEX RANGE SCAN| IDX_LUNARTEST1_N |     1 |     4 |     1   (0)| 00:00:01 |
-------------------------------------------------------------------------------------

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

   1 - access("N"=1)

Note
-----
   - SQL plan baseline "SQL_PLAN_0k9pqn7v9yvuw02b73393" used for this statement


Statistics
----------------------------------------------------------
         59  recursive calls
         52  db block gets
         36  consistent gets
          1  physical reads
      15312  redo size
        519  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

LUNAR@lunardb>

这里看到已经使用了SPM中的SQL Profile:SQL_PLAN_0k9pqn7v9yvuw02b73393
总结:
这里已经使用了我们的SPM(SQL_PLAN_0k9pqn7v9yvuw02b73393)固定了执行计划,sql使用了索引
说明SPM绑定执行计划的方式比hint的优先级高

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