基于advisor优化工具的一次sql优化

2019年10月19日 162次阅读 来源: DBA_每日记

问题背景：

客户反馈升级补丁包后DB服务器CPU压力增致99%


解决思路：

1> 查看问题系统发现有大量的latch: cache buffers chains 等待 ；

latch:cache buffers chains出现的原因   

1、不够优化的SQL。   

大量逻辑读的SQL语句就有可能产生非常严重的latch:cache buffers chains等待，因为每次要访问一个block，

就需要获得该latch，由于有大量的逻辑读，那么就增加了latch:cache buffers chains争用的机率。   

对于正在运行的SQL语句，产生非常严重的latch:cache buffers chains争用，可以利用下面SQL查看执行计划，并设法优化SQL语句。

select * from table(dbms_xplan.display_cursor(‘sql_id’,sql_child_number));   

如果SQL已经运行完毕，我们就看AWR报表里面的SQL Statistics->SQL ordered by Gets->Gets per Exec，试图优化这些SQL。

2、热点块争用  

查找数据库是否存在latch的争用

select sid,event,p1text,p1raw from v$session_wait where event=’latch: cache buffers chains’

配合awr报告查看

《基于advisor优化工具的一次sql优化》

《基于advisor优化工具的一次sql优化》

《基于advisor优化工具的一次sql优化》

可以确认确实有大量的latch：cache buffers chains 等待


2> 根据客户反馈昨天刚刚升级完毕补丁包并且补丁包里有

新上线的sql，怀疑是新的sql不够优化导致

首先把DB服务器的cpu降下来，kill latch: cache buffers chains 会话

select ‘alter system kill session ”’ || a.sid || ‘,’ || serial# || ”’ immediate;’

  from v$session a

 where a.username=’ECOLOGY’ 

 AND a.STATUS=’ACTIVE’    

 and event in(‘latch: cache buffers chains’,’latch free’)

 alter system kill session ‘56,18142’ ;

alter system kill session ‘319,1510’ ;

alter system kill session ‘1462,17432’ ;

alter system kill session ‘3456,2847’ ;

alter system kill session ‘3457,1717’ ;

alter system kill session ‘3458,16756’ ;

alter system kill session ‘3739,7185’ ;

alter system kill session ‘4000,2064’ ;

 

3> 根据sql_id 查看问题sql的执行计划

SQL_ID  gj9y6g28qx8hw, child number 3

————————————-

Plan hash value: 563984120

《基于advisor优化工具的一次sql优化》

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

————————————————————-

 

   1 – SEL$6D6869C2

   7 – SEL$6D6869C2 / WORKFLOWCENTERSETTINGDETAIL@SEL$3

  10 – SEL$6D6869C2 / WORKFLOWCENTERSETTINGDETAIL@SEL$4

  12 – SEL$6D6869C2 / T1@SEL$2

  13 – SEL$6D6869C2 / T2@SEL$2

  14 – SEL$6D6869C2 / T2@SEL$2

  15 – SEL$6D6869C2 / WORKFLOW_BASE@SEL$5

  16 – SEL$6D6869C2 / WORKFLOW_BASE@SEL$5

 

Outline Data

————-

 

  /*+

      BEGIN_OUTLINE_DATA

      IGNORE_OPTIM_EMBEDDED_HINTS

      OPTIMIZER_FEATURES_ENABLE(‘11.2.0.1’)

      DB_VERSION(‘11.2.0.1’)

      ALL_ROWS

      OUTLINE_LEAF(@”SEL$6D6869C2″)

      UNNEST(@”SEL$3″)

      UNNEST(@”SEL$4″)

      UNNEST(@”SEL$5″)

      OUTLINE(@”SEL$F5BB74E1″)

      MERGE(@”SEL$2″)

      OUTLINE(@”SEL$3″)

      OUTLINE(@”SEL$4″)

      OUTLINE(@”SEL$5″)

      OUTLINE(@”SEL$1″)

      OUTLINE(@”SEL$2″)

      INDEX(@”SEL$6D6869C2″ “WORKFLOWCENTERSETTINGDETAIL”@”SEL$3” (“WORKFLOWCENTERSETTINGDETAIL”.”EID” 

              “WORKFLOWCENTERSETTINGDETAIL”.”TABID” “WORKFLOWCENTERSETTINGDETAIL”.”TYPE” 

              “WORKFLOWCENTERSETTINGDETAIL”.”CONTENT”))

      INDEX(@”SEL$6D6869C2″ “WORKFLOWCENTERSETTINGDETAIL”@”SEL$4” (“WORKFLOWCENTERSETTINGDETAIL”.”EID” 

              “WORKFLOWCENTERSETTINGDETAIL”.”TABID” “WORKFLOWCENTERSETTINGDETAIL”.”TYPE” 

              “WORKFLOWCENTERSETTINGDETAIL”.”CONTENT”))

      FULL(@”SEL$6D6869C2″ “T1″@”SEL$2”)

      INDEX_RS_ASC(@”SEL$6D6869C2″ “T2″@”SEL$2” (“WORKFLOW_CURRENTOPERATOR”.”REQUESTID” 

              “WORKFLOW_CURRENTOPERATOR”.”USERID” “WORKFLOW_CURRENTOPERATOR”.”WORKFLOWID”))

      INDEX_RS_ASC(@”SEL$6D6869C2″ “WORKFLOW_BASE”@”SEL$5” (“WORKFLOW_BASE”.”ID”))

      LEADING(@”SEL$6D6869C2″ “WORKFLOWCENTERSETTINGDETAIL”@”SEL$3” “WORKFLOWCENTERSETTINGDETAIL”@”SEL$4” 

              “T1″@”SEL$2” “T2″@”SEL$2” “WORKFLOW_BASE”@”SEL$5”)

      USE_MERGE(@”SEL$6D6869C2″ “WORKFLOWCENTERSETTINGDETAIL”@”SEL$4”)

      USE_MERGE_CARTESIAN(@”SEL$6D6869C2″ “T1″@”SEL$2”)

      USE_NL(@”SEL$6D6869C2″ “T2″@”SEL$2”)

      USE_NL(@”SEL$6D6869C2″ “WORKFLOW_BASE”@”SEL$5”)

      END_OUTLINE_DATA

  */

 

Predicate Information (identified by operation id):

—————————————————

 

   7 – access(“EID”=962 AND “TABID”=5 AND “TYPE”=’typeid’)

  10 – access(“EID”=962 AND “TABID”=5 AND “TYPE”=’flowid’)

  12 – filter(((“T1”.”DELETED”=0 OR “T1″.”DELETED” IS NULL) AND (“T1″.”CURRENTSTATUS” IS NULL OR 

              “T1”.”CURRENTSTATUS”<>1)))

  13 – filter((“T2”.”VIEWTYPE”=0 AND “T2”.”ISLASTTIMES”=1 AND INTERNAL_FUNCTION(“T2″.”ISREMARK”) AND 

可以看出执行计划非常糟糕，这次不手工调优，尝试使用advisor工具

调优建议如下：

GENERAL INFORMATION SECTION

——————————————————————————-

Tuning Task Name   : staName58179

Tuning Task Owner  : username

Tuning Task ID     : 20591

Workload Type      : Single SQL Statement

Execution Count    : 1

Current Execution  : EXEC_18371

Execution Type     : TUNE SQL

Scope              : COMPREHENSIVE

Time Limit(seconds): 1800

Completion Status  : COMPLETED

Started at         : 10/17/2019 16:42:31

Completed at       : 10/17/2019 16:42:35


——————————————————————————-

Schema Name: username

SQL ID     : 48k1mg3r7vqms

SQL Text   : 

——————————————————————————-

FINDINGS SECTION (2 findings)

——————————————————————————-


1- Statistics Finding     

——————— 

  表 “username”.”table_name” 的优化程序统计信息已失效。


  Recommendation

  ————–

  – 考虑收集此表及其索引的优化程序统计信息。

    execute dbms_stats.gather_table_stats(ownname => ‘username’, tabname =>

            ‘table_name’, estimate_percent =>

            DBMS_STATS.AUTO_SAMPLE_SIZE, method_opt => ‘FOR ALL COLUMNS SIZE

            AUTO’, cascade => TRUE);


  Rationale

  ———

    为了选择好的执行计划, 优化程序需要此表及其索引的最新统计信息。


2- SQL Profile Finding (see explain plans section below)

——————————————————–

  为此语句找到了性能更好的执行计划。


  Recommendation (estimated benefit: 99.95%)

  ——————————————

  – 考虑接受推荐的 SQL 概要文件。

    execute dbms_sqltune.accept_sql_profile(task_name => ‘staName58179’,

            task_owner => ‘username’, replace => TRUE);


  Validation results

  ——————

  已对 SQL profile 进行测试, 方法为执行其计划和原始计划并测量与计划相对应的执行统计信息。如果其中一个计划运行在很短的时间内就完成,

  则另一计划可能只执行了一部分。


                           Original Plan  With SQL Profile  % Improved

                           ————-  —————-  ———-

  Completion Status:            COMPLETE          COMPLETE

  Elapsed Time(us):               76070               265      99.65 %

  CPU Time(us):                   61690               299      99.51 %

  User I/O Time(us):                  0                 0 

  Buffer Gets:                    36545                17      99.95 %

  Physical Read Requests:             0                 0 

  Physical Write Requests:            0                 0 

  Physical Read Bytes:                0                 0 

  Physical Write Bytes:               0                 0 

  Rows Processed:                     1                 1 

  Fetches:                            1                 1 

  Executions:                         1                 1 


  Notes

  —–

  1. original plan 已首先执行以预热缓冲区高速缓存。

  2. original plan 的统计信息是后面的 9 执行的平均值。

  3. SQL profile plan 已首先执行以预热缓冲区高速缓存。

  4. the SQL profile plan 的统计信息是后面的 9 执行的平均值。


——————————————————————————-

EXPLAIN PLANS SECTION

——————————————————————————-

《基于advisor优化工具的一次sql优化》

1- Original

———–

Plan hash value: 2478385950


 

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

————————————————————-

 

   1 – SEL$6D6869C2

   8 – SEL$6D6869C2 / WORKFLOWCENTERSETTINGDETAIL@SEL$3

  11 – SEL$6D6869C2 / WORKFLOWCENTERSETTINGDETAIL@SEL$4

  13 – SEL$6D6869C2 / T2@SEL$2

  14 – SEL$6D6869C2 / T2@SEL$2

  15 – SEL$6D6869C2 / WORKFLOW_BASE@SEL$5

  16 – SEL$6D6869C2 / WORKFLOW_BASE@SEL$5

  17 – SEL$6D6869C2 / T1@SEL$2

  18 – SEL$6D6869C2 / T1@SEL$2

 

Predicate Information (identified by operation id):

—————————————————

 

   8 – access(“EID”=962 AND “TABID”=5 AND “TYPE”=’typeid’)

  11 – access(“EID”=962 AND “TABID”=5 AND “TYPE”=’flowid’)

  13 – filter(“T2”.”VIEWTYPE”=0 AND “T2”.”ISLASTTIMES”=1 AND “T2”.”WORKFLOWTYPE”=TO_NUMBER(“CONTENT”) AND 

              “T2”.”WORKFLOWID”=TO_NUMBER(“CONTENT”))

  14 – access((“T2”.”ISREMARK”=’7′ OR “T2”.”ISREMARK”=’8′ OR “T2”.”ISREMARK”=’9′) AND “T2”.”USERID”=695 

              AND “T2”.”USERTYPE”=0)

  15 – filter(“ISVALID”=’1′ OR “ISVALID”=’3′)

  16 – access(“T2″.”WORKFLOWID”=”ID”)

  17 – access(“T1″.”REQUESTID”=”T2″.”REQUESTID”)

  18 – filter((“T1”.”DELETED”=0 OR “T1″.”DELETED” IS NULL) AND (“T1″.”CURRENTSTATUS” IS NULL OR 

              “T1”.”CURRENTSTATUS”<>1))

 

Column Projection Information (identified by operation id):

———————————————————–

 

   1 – (#keys=0) COUNT(*)[22]

   2 – (#keys=0) 

   3 – (#keys=0) “T1”.ROWID[ROWID,10]

   4 – (#keys=0) “T2”.”REQUESTID”[NUMBER,22]

   5 – (#keys=0) “T2”.”REQUESTID”[NUMBER,22], “T2”.”WORKFLOWID”[NUMBER,22]

   6 – (#keys=0) TO_NUMBER(“CONTENT”)[22], TO_NUMBER(“CONTENT”)[22]

   7 – (#keys=1) TO_NUMBER(“CONTENT”)[22]

   8 – “CONTENT”[VARCHAR2,100]

   9 – (#keys=0) TO_NUMBER(“CONTENT”)[22]

  10 – (#keys=1) TO_NUMBER(“CONTENT”)[22]

  11 – “CONTENT”[VARCHAR2,100]

  12 – “T2”.”REQUESTID”[NUMBER,22], “T2”.”WORKFLOWID”[NUMBER,22]

  13 – “T2”.”REQUESTID”[NUMBER,22], “T2”.”WORKFLOWID”[NUMBER,22]

  14 – “T2”.ROWID[ROWID,10]

  16 – “WORKFLOW_BASE”.ROWID[ROWID,10]

  17 – “T1”.ROWID[ROWID,10]


2- Original With Adjusted Cost

——————————

Plan hash value: 2478385950

《基于advisor优化工具的一次sql优化》

 

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

————————————————————-

 

   1 – SEL$6D6869C2

   8 – SEL$6D6869C2 / WORKFLOWCENTERSETTINGDETAIL@SEL$3

  11 – SEL$6D6869C2 / WORKFLOWCENTERSETTINGDETAIL@SEL$4

  13 – SEL$6D6869C2 / T2@SEL$2

  14 – SEL$6D6869C2 / T2@SEL$2

  15 – SEL$6D6869C2 / WORKFLOW_BASE@SEL$5

  16 – SEL$6D6869C2 / WORKFLOW_BASE@SEL$5

  17 – SEL$6D6869C2 / T1@SEL$2

  18 – SEL$6D6869C2 / T1@SEL$2

 

Predicate Information (identified by operation id):

—————————————————

 

   8 – access(“EID”=962 AND “TABID”=5 AND “TYPE”=’typeid’)

  11 – access(“EID”=962 AND “TABID”=5 AND “TYPE”=’flowid’)

  13 – filter(“T2”.”VIEWTYPE”=0 AND “T2”.”ISLASTTIMES”=1 AND “T2”.”WORKFLOWTYPE”=TO_NUMBER(“CONTENT”) AND 

              “T2”.”WORKFLOWID”=TO_NUMBER(“CONTENT”))

  14 – access((“T2”.”ISREMARK”=’7′ OR “T2”.”ISREMARK”=’8′ OR “T2”.”ISREMARK”=’9′) AND “T2”.”USERID”=695 

              AND “T2”.”USERTYPE”=0)

  15 – filter(“ISVALID”=’1′ OR “ISVALID”=’3′)

  16 – access(“T2″.”WORKFLOWID”=”ID”)

  17 – access(“T1″.”REQUESTID”=”T2″.”REQUESTID”)

  18 – filter((“T1”.”DELETED”=0 OR “T1″.”DELETED” IS NULL) AND (“T1″.”CURRENTSTATUS” IS NULL OR 

              “T1”.”CURRENTSTATUS”<>1))

 

Column Projection Information (identified by operation id):

———————————————————–

 

   1 – (#keys=0) COUNT(*)[22]

   2 – (#keys=0) 

   3 – (#keys=0) “T1”.ROWID[ROWID,10]

   4 – (#keys=0) “T2”.”REQUESTID”[NUMBER,22]

   5 – (#keys=0) “T2”.”REQUESTID”[NUMBER,22], “T2”.”WORKFLOWID”[NUMBER,22]

   6 – (#keys=0) TO_NUMBER(“CONTENT”)[22], TO_NUMBER(“CONTENT”)[22]

   7 – (#keys=1) TO_NUMBER(“CONTENT”)[22]

   8 – “CONTENT”[VARCHAR2,100]

   9 – (#keys=0) TO_NUMBER(“CONTENT”)[22]

  10 – (#keys=1) TO_NUMBER(“CONTENT”)[22]

  11 – “CONTENT”[VARCHAR2,100]

  12 – “T2”.”REQUESTID”[NUMBER,22], “T2”.”WORKFLOWID”[NUMBER,22]

  13 – “T2”.”REQUESTID”[NUMBER,22], “T2”.”WORKFLOWID”[NUMBER,22]

  14 – “T2”.ROWID[ROWID,10]

  16 – “WORKFLOW_BASE”.ROWID[ROWID,10]

  17 – “T1”.ROWID[ROWID,10]


3- Using SQL Profile

——————–

Plan hash value: 1474559118

《基于advisor优化工具的一次sql优化》

 

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

————————————————————-

 

   1 – SEL$6D6869C2

   7 – SEL$6D6869C2 / T2@SEL$2

   8 – SEL$6D6869C2 / T2@SEL$2

   9 – SEL$6D6869C2 / WORKFLOWCENTERSETTINGDETAIL@SEL$3

  10 – SEL$6D6869C2 / T1@SEL$2

  11 – SEL$6D6869C2 / T1@SEL$2

  12 – SEL$6D6869C2 / WORKFLOW_BASE@SEL$5

  13 – SEL$6D6869C2 / WORKFLOW_BASE@SEL$5

  14 – SEL$6D6869C2 / WORKFLOWCENTERSETTINGDETAIL@SEL$4

 

Predicate Information (identified by operation id):

—————————————————

 

   5 – access(“T2”.”WORKFLOWTYPE”=TO_NUMBER(“CONTENT”))

   7 – filter(“T2”.”VIEWTYPE”=0 AND “T2”.”ISLASTTIMES”=1)

   8 – access((“T2”.”ISREMARK”=’7′ OR “T2”.”ISREMARK”=’8′ OR “T2”.”ISREMARK”=’9′) AND “T2”.”USERID”=695 

              AND “T2”.”USERTYPE”=0)

   9 – access(“EID”=962 AND “TABID”=5 AND “TYPE”=’typeid’)

  10 – filter((“T1”.”DELETED”=0 OR “T1″.”DELETED” IS NULL) AND (“T1″.”CURRENTSTATUS” IS NULL OR 

              “T1”.”CURRENTSTATUS”<>1))

  11 – access(“T1″.”REQUESTID”=”T2″.”REQUESTID”)

  12 – filter(“ISVALID”=’1′ OR “ISVALID”=’3′)

  13 – access(“T2″.”WORKFLOWID”=”ID”)

  14 – access(“EID”=962 AND “TABID”=5 AND “TYPE”=’flowid’)

       filter(“T2”.”WORKFLOWID”=TO_NUMBER(“CONTENT”))

 

Column Projection Information (identified by operation id):

———————————————————–

 

   1 – (#keys=0) COUNT(*)[22]

   2 – (#keys=0) 

   3 – (#keys=0) “T2”.”WORKFLOWID”[NUMBER,22]

   4 – (#keys=0) “T2”.”WORKFLOWID”[NUMBER,22]

   5 – (#keys=1) “T2”.”REQUESTID”[NUMBER,22], “T2”.”WORKFLOWID”[NUMBER,22]

   6 – “T2”.”REQUESTID”[NUMBER,22], “T2”.”WORKFLOWID”[NUMBER,22], “T2”.”WORKFLOWTYPE”[NUMBER,22]

   7 – “T2”.”REQUESTID”[NUMBER,22], “T2”.”WORKFLOWID”[NUMBER,22], “T2”.”WORKFLOWTYPE”[NUMBER,22]

   8 – “T2”.ROWID[ROWID,10]

   9 – “CONTENT”[VARCHAR2,100]

  11 – “T1”.ROWID[ROWID,10]

  13 – “WORKFLOW_BASE”.ROWID[ROWID,10]


——————————————————————————-

advisor建议收集统计信息

execute dbms_stats.gather_table_stats(ownname => ‘username’, tabname => ‘table_name’, estimate_percent => DBMS_STATS.AUTO_SAMPLE_SIZE, method_opt => ‘FOR ALL COLUMNS SIZE AUTO’, cascade => TRUE);

建议绑定良好的执行计划

execute dbms_sqltune.accept_sql_profile(task_name => ‘staName58179’,task_owner => ‘usrename’, replace => TRUE);

4> 根据advisor给出的建议实际查看相关表是否统计信息失效，确实发现相关表的统计信息失效，收集完毕统计信息再次执行advisor测试


GENERAL INFORMATION SECTION

——————————————————————————-

Tuning Task Name   : staName86486

Tuning Task Owner  : username

Tuning Task ID     : 20592

Workload Type      : Single SQL Statement

Execution Count    : 1

Current Execution  : EXEC_18372

Execution Type     : TUNE SQL

Scope              : COMPREHENSIVE

Time Limit(seconds): 1800

Completion Status  : COMPLETED

Started at         : 10/17/2019 16:48:25

Completed at       : 10/17/2019 16:48:26


——————————————————————————-

Schema Name: username

SQL ID     : 48k1mg3r7vqms

SQL Text   : 

——————————————————————————-

ADDITIONAL INFORMATION SECTION

——————————————————————————-

– 此语句的 SQL 概要文件 “SYS_SQLPROF_016dd8e4cbcb0000” 已存在, 但在优化时被忽略。

——————————————————————————-

EXPLAIN PLANS SECTION

——————————————————————————-


1- Original

———–

Plan hash value: 1474559118

  《基于advisor优化工具的一次sql优化》

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

————————————————————-

 

   1 – SEL$6D6869C2

   7 – SEL$6D6869C2 / T2@SEL$2

   8 – SEL$6D6869C2 / T2@SEL$2

   9 – SEL$6D6869C2 / WORKFLOWCENTERSETTINGDETAIL@SEL$3

  10 – SEL$6D6869C2 / T1@SEL$2

  11 – SEL$6D6869C2 / T1@SEL$2

  12 – SEL$6D6869C2 / WORKFLOW_BASE@SEL$5

  13 – SEL$6D6869C2 / WORKFLOW_BASE@SEL$5

  14 – SEL$6D6869C2 / WORKFLOWCENTERSETTINGDETAIL@SEL$4

 

Predicate Information (identified by operation id):

—————————————————

 

   5 – access(“T2”.”WORKFLOWTYPE”=TO_NUMBER(“CONTENT”))

   7 – filter(“T2”.”VIEWTYPE”=0 AND “T2”.”ISLASTTIMES”=1)

   8 – access((“T2”.”ISREMARK”=’7′ OR “T2”.”ISREMARK”=’8′ OR “T2”.”ISREMARK”=’9′) AND “T2”.”USERID”=695 

              AND “T2”.”USERTYPE”=0)

   9 – access(“EID”=962 AND “TABID”=5 AND “TYPE”=’typeid’)

  10 – filter((“T1”.”DELETED”=0 OR “T1″.”DELETED” IS NULL) AND (“T1″.”CURRENTSTATUS” IS NULL OR 

              “T1”.”CURRENTSTATUS”<>1))

  11 – access(“T1″.”REQUESTID”=”T2″.”REQUESTID”)

  12 – filter(“ISVALID”=’1′ OR “ISVALID”=’3′)

  13 – access(“T2″.”WORKFLOWID”=”ID”)

  14 – access(“EID”=962 AND “TABID”=5 AND “TYPE”=’flowid’)

       filter(“T2”.”WORKFLOWID”=TO_NUMBER(“CONTENT”))

 

Column Projection Information (identified by operation id):

———————————————————–

 

   1 – (#keys=0) COUNT(*)[22]

   2 – (#keys=0) 

   3 – (#keys=0) “T2”.”WORKFLOWID”[NUMBER,22]

   4 – (#keys=0) “T2”.”WORKFLOWID”[NUMBER,22]

   5 – (#keys=1) “T2”.”REQUESTID”[NUMBER,22], “T2”.”WORKFLOWID”[NUMBER,22]

   6 – “T2”.”REQUESTID”[NUMBER,22], “T2”.”WORKFLOWID”[NUMBER,22], “T2”.”WORKFLOWTYPE”[NUMBER,22]

   7 – “T2”.”REQUESTID”[NUMBER,22], “T2”.”WORKFLOWID”[NUMBER,22], “T2”.”WORKFLOWTYPE”[NUMBER,22]

   8 – “T2”.ROWID[ROWID,10]

   9 – “CONTENT”[VARCHAR2,100]

  11 – “T1”.ROWID[ROWID,10]

  13 – “WORKFLOW_BASE”.ROWID[ROWID,10]

 

Note

—–

   – SQL profile “SYS_SQLPROF_016dd8e4cbcb0000” used for this statement


——————————————————————————-

advisor工具没有给出合理的调整，说明advisor工具判断目前的sql执行计划良好，再次执行相关sql结果秒出

查看DB服务器负载已经正常，调优成功











































    原文作者：DBA_每日记
    原文地址: http://blog.itpub.net/69950231/viewspace-2660473/
    本文转自网络文章，转载此文章仅为分享知识，如有侵权，请联系博主进行删除。
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