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

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

    转载自：http://www.lunar2013.com/2016/01/固定执行计划-使用spm%EF%BC%88sql-plan-management%EF%BC%89固定执行计划.html

    .
    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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  • 原文地址：https://www.cnblogs.com/xibuhaohao/p/10271503.html
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