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
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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
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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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