advisor调优工具优化sql(基于sql_id)

来源：这里教程网时间：2026-03-03 14:25:16 作者：

advisor调优工具优化sql(基于sql_id) 问题背景：客户反馈数据库迁移后cpu负载激增，帮忙查看原因解决思路： 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$session_wait where event='latch: cache buffers chains' 首先把DB服务器的cpu降下来，kill latch: cache buffers chains 会话 select 'alter system kill session ''' || a.sid || ',' || serial# || ''';' from v$session a where a.username='USERNAME' 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' ; 2> 根据sql_id查看问题sql的执行计划，（有三个执行计划） SQL> select * from table(dbms_xplan.display_awr('&1')); Enter value for 1: a6su7qgyywvn8 old 1: select * from table(dbms_xplan.display_awr('&1')) new 1: select * from table(dbms_xplan.display_awr('a6su7qgyywvn8')) PLAN_TABLE_OUTPUT -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- SQL_ID a6su7qgyywvn8 -------------------- Plan hash value: 1019409405 --------------------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | --------------------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | | | 331 (100)| | | 1 | VIEW | | 532 | 205K| 331 (1)| 00:00:04 | | 2 | COUNT | | | | | | | 3 | VIEW | | 532 | 198K| 331 (1)| 00:00:04 | | 4 | SORT ORDER BY | | 532 | 192K| 331 (1)| 00:00:04 | | 5 | COUNT | | | | | | | 6 | VIEW | | 532 | 192K| 331 (1)| 00:00:04 | | 7 | HASH UNIQUE | | 532 | 97K| 331 (1)| 00:00:04 | | 8 | CONCATENATION | | | | | | | 9 | FILTER | | | | | | | 10 | NESTED LOOPS | | 1 | 188 | 12 (0)| 00:00:01 | | 11 | NESTED LOOPS | | 1 | 169 | 11 (0)| 00:00:01 | | 12 | NESTED LOOPS | | 1 | 90 | 10 (0)| 00:00:01 | | 13 | NESTED LOOPS | | 1 | 84 | 9 (0)| 00:00:01 | | 14 | INDEX FAST FULL SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 4 (0)| 00:00:01 | | 15 | INLIST ITERATOR | | | | | | | 16 | TABLE ACCESS BY INDEX ROWID| WORKFLOW_CURRENTOPERATOR | 1 | 65 | 5 (0)| 00:00:01 | | 17 | INDEX RANGE SCAN | WRKCUOPER_USER_IN2 | 1 | | 4 (0)| 00:00:01 | | 18 | TABLE ACCESS BY INDEX ROWID | WORKFLOW_BASE | 1 | 6 | 1 (0)| 00:00:01 | | 19 | INDEX RANGE SCAN | IX_WFBASE_ID | 1 | | 0 (0)| | | 20 | TABLE ACCESS BY INDEX ROWID | WORKFLOW_REQUESTBASE | 1 | 79 | 1 (0)| 00:00:01 | | 21 | INDEX UNIQUE SCAN | WORKFLOW_REQUESTID | 1 | | 0 (0)| | | 22 | INDEX RANGE SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 1 (0)| 00:00:01 | | 23 | INDEX RANGE SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 2 (0)| 00:00:01 | | 24 | NESTED LOOPS | | 1 | 35 | 3 (0)| 00:00:01 | | 25 | MERGE JOIN CARTESIAN | | 1 | 26 | 2 (0)| 00:00:01 | | 26 | INDEX RANGE SCAN | IX_WORKFLOW_NODEBASE_IDIS | 1 | 7 | 1 (0)| 00:00:01 | | 27 | BUFFER SORT | | 1 | 19 | 1 (0)| 00:00:01 | | 28 | INDEX RANGE SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 1 (0)| 00:00:01 | | 29 | INDEX RANGE SCAN | IX_WKFFLND_NW | 1 | 9 | 1 (0)| 00:00:01 | | 30 | FILTER | | | | | | | 31 | NESTED LOOPS | | | | | | | 32 | NESTED LOOPS | | 1 | 188 | 318 (0)| 00:00:04 | | 33 | NESTED LOOPS | | 1 | 182 | 317 (0)| 00:00:04 | | 34 | NESTED LOOPS | | 1 | 163 | 316 (0)| 00:00:04 | | 35 | NESTED LOOPS | | 1 | 84 | 315 (0)| 00:00:04 | | 36 | INDEX FAST FULL SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 4 (0)| 00:00:01 | | 37 | TABLE ACCESS BY INDEX ROWID| WORKFLOW_CURRENTOPERATOR | 7 | 455 | 311 (0)| 00:00:04 | | 38 | INDEX RANGE SCAN | USERANDREQUESTID | 316 | | 3 (0)| 00:00:01 | | 39 | TABLE ACCESS BY INDEX ROWID | WORKFLOW_REQUESTBASE | 1 | 79 | 1 (0)| 00:00:01 | | 40 | INDEX UNIQUE SCAN | WORKFLOW_REQUESTID | 1 | | 0 (0)| | | 41 | INDEX RANGE SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 1 (0)| 00:00:01 | | 42 | INDEX RANGE SCAN | IX_WFBASE_ID | 1 | | 0 (0)| | | 43 | TABLE ACCESS BY INDEX ROWID | WORKFLOW_BASE | 5 | 30 | 1 (0)| 00:00:01 | | 44 | INDEX RANGE SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 2 (0)| 00:00:01 | | 45 | NESTED LOOPS | | 1 | 35 | 3 (0)| 00:00:01 | | 46 | MERGE JOIN CARTESIAN | | 1 | 26 | 2 (0)| 00:00:01 | | 47 | INDEX RANGE SCAN | IX_WORKFLOW_NODEBASE_IDIS | 1 | 7 | 1 (0)| 00:00:01 | | 48 | BUFFER SORT | | 1 | 19 | 1 (0)| 00:00:01 | | 49 | INDEX RANGE SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 1 (0)| 00:00:01 | | 50 | INDEX RANGE SCAN | IX_WKFFLND_NW | 1 | 9 | 1 (0)| 00:00:01 | --------------------------------------------------------------------------------------------------------------------------- Note ----- - cardinality feedback used for this statement SQL_ID a6su7qgyywvn8 -------------------- Plan hash value: 1061600654 --------------------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | --------------------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | | | 1507 (100)| | | 1 | VIEW | | 532 | 205K| 1507 (1)| 00:00:19 | | 2 | COUNT | | | | | | | 3 | VIEW | | 532 | 198K| 1507 (1)| 00:00:19 | | 4 | SORT ORDER BY | | 532 | 192K| 1507 (1)| 00:00:19 | | 5 | COUNT | | | | | | | 6 | VIEW | | 532 | 192K| 1507 (1)| 00:00:19 | | 7 | HASH UNIQUE | | 532 | 97K| 1507 (1)| 00:00:19 | | 8 | CONCATENATION | | | | | | | 9 | FILTER | | | | | | | 10 | NESTED LOOPS | | 1 | 188 | 12 (0)| 00:00:01 | | 11 | NESTED LOOPS | | 1 | 169 | 11 (0)| 00:00:01 | | 12 | NESTED LOOPS | | 1 | 90 | 10 (0)| 00:00:01 | | 13 | NESTED LOOPS | | 1 | 84 | 9 (0)| 00:00:01 | | 14 | INDEX FAST FULL SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 4 (0)| 00:00:01 | | 15 | INLIST ITERATOR | | | | | | | 16 | TABLE ACCESS BY INDEX ROWID| WORKFLOW_CURRENTOPERATOR | 1 | 65 | 5 (0)| 00:00:01 | | 17 | INDEX RANGE SCAN | WRKCUOPER_USER_IN2 | 1 | | 4 (0)| 00:00:01 | | 18 | TABLE ACCESS BY INDEX ROWID | WORKFLOW_BASE | 1 | 6 | 1 (0)| 00:00:01 | | 19 | INDEX RANGE SCAN | IX_WFBASE_ID | 1 | | 0 (0)| | | 20 | TABLE ACCESS BY INDEX ROWID | WORKFLOW_REQUESTBASE | 1 | 79 | 1 (0)| 00:00:01 | | 21 | INDEX UNIQUE SCAN | WORKFLOW_REQUESTID | 1 | | 0 (0)| | | 22 | INDEX RANGE SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 1 (0)| 00:00:01 | | 23 | INDEX RANGE SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 2 (0)| 00:00:01 | | 24 | NESTED LOOPS | | 1 | 35 | 3 (0)| 00:00:01 | | 25 | MERGE JOIN CARTESIAN | | 1 | 26 | 2 (0)| 00:00:01 | | 26 | INDEX RANGE SCAN | IX_WORKFLOW_NODEBASE_IDIS | 1 | 7 | 1 (0)| 00:00:01 | | 27 | BUFFER SORT | | 1 | 19 | 1 (0)| 00:00:01 | | 28 | INDEX RANGE SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 1 (0)| 00:00:01 | | 29 | INDEX RANGE SCAN | IX_WKFFLND_NW | 1 | 9 | 1 (0)| 00:00:01 | | 30 | FILTER | | | | | | | 31 | NESTED LOOPS | | | | | | | 32 | NESTED LOOPS | | 1 | 188 | 1494 (1)| 00:00:18 | | 33 | NESTED LOOPS | | 1 | 182 | 1493 (1)| 00:00:18 | | 34 | MERGE JOIN CARTESIAN | | 40 | 4680 | 1373 (1)| 00:00:17 | | 35 | MERGE JOIN CARTESIAN | | 1 | 38 | 5 (0)| 00:00:01 | | 36 | INDEX FAST FULL SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 4 (0)| 00:00:01 | | 37 | BUFFER SORT | | 1 | 19 | 1 (0)| 00:00:01 | | 38 | INDEX RANGE SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 1 (0)| 00:00:01 | | 39 | BUFFER SORT | | 105K| 8150K| 1372 (1)| 00:00:17 | | 40 | TABLE ACCESS FULL | WORKFLOW_REQUESTBASE | 105K| 8150K| 1368 (1)| 00:00:17 | | 41 | TABLE ACCESS BY INDEX ROWID | WORKFLOW_CURRENTOPERATOR | 1 | 65 | 3 (0)| 00:00:01 | | 42 | INDEX RANGE SCAN | WORKFLOWUSERANDID | 1 | | 2 (0)| 00:00:01 | | 43 | INDEX RANGE SCAN | IX_WFBASE_ID | 1 | | 0 (0)| | | 44 | TABLE ACCESS BY INDEX ROWID | WORKFLOW_BASE | 5 | 30 | 1 (0)| 00:00:01 | | 45 | INDEX RANGE SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 2 (0)| 00:00:01 | | 46 | NESTED LOOPS | | 1 | 35 | 3 (0)| 00:00:01 | | 47 | MERGE JOIN CARTESIAN | | 1 | 26 | 2 (0)| 00:00:01 | | 48 | INDEX RANGE SCAN | IX_WORKFLOW_NODEBASE_IDIS | 1 | 7 | 1 (0)| 00:00:01 | | 49 | BUFFER SORT | | 1 | 19 | 1 (0)| 00:00:01 | | 50 | INDEX RANGE SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 1 (0)| 00:00:01 | | 51 | INDEX RANGE SCAN | IX_WKFFLND_NW | 1 | 9 | 1 (0)| 00:00:01 | --------------------------------------------------------------------------------------------------------------------------- Note ----- - cardinality feedback used for this statement SQL_ID a6su7qgyywvn8 -------------------- Plan hash value: 1147966846 --------------------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | --------------------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | | | 24 (100)| | | 1 | VIEW | | 1 | 396 | 24 (5)| 00:00:01 | | 2 | COUNT | | | | | | | 3 | VIEW | | 1 | 383 | 24 (5)| 00:00:01 | | 4 | SORT ORDER BY | | 1 | 370 | 24 (5)| 00:00:01 | | 5 | COUNT | | | | | | | 6 | VIEW | | 1 | 370 | 24 (5)| 00:00:01 | | 7 | HASH UNIQUE | | 1 | 188 | 24 (5)| 00:00:01 | | 8 | CONCATENATION | | | | | | | 9 | FILTER | | | | | | | 10 | NESTED LOOPS | | | | | | | 11 | NESTED LOOPS | | 1 | 188 | 10 (0)| 00:00:01 | | 12 | NESTED LOOPS | | 1 | 109 | 9 (0)| 00:00:01 | | 13 | NESTED LOOPS | | 1 | 103 | 8 (0)| 00:00:01 | | 14 | MERGE JOIN CARTESIAN | | 1 | 38 | 3 (0)| 00:00:01 | | 15 | INDEX RANGE SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 2 (0)| 00:00:01 | | 16 | BUFFER SORT | | 1 | 19 | 1 (0)| 00:00:01 | | 17 | INDEX RANGE SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 1 (0)| 00:00:01 | | 18 | INLIST ITERATOR | | | | | | | 19 | TABLE ACCESS BY INDEX ROWID| WORKFLOW_CURRENTOPERATOR | 1 | 65 | 5 (0)| 00:00:01 | | 20 | INDEX RANGE SCAN | WRKCUOPER_USER_IN2 | 1 | | 4 (0)| 00:00:01 | | 21 | TABLE ACCESS BY INDEX ROWID | WORKFLOW_BASE | 1 | 6 | 1 (0)| 00:00:01 | | 22 | INDEX RANGE SCAN | IX_WFBASE_ID | 1 | | 0 (0)| | | 23 | INDEX UNIQUE SCAN | WORKFLOW_REQUESTID | 1 | | 0 (0)| | | 24 | TABLE ACCESS BY INDEX ROWID | WORKFLOW_REQUESTBASE | 1 | 79 | 1 (0)| 00:00:01 | | 25 | INDEX RANGE SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 2 (0)| 00:00:01 | | 26 | NESTED LOOPS | | 1 | 35 | 3 (0)| 00:00:01 | | 27 | MERGE JOIN CARTESIAN | | 1 | 26 | 2 (0)| 00:00:01 | | 28 | INDEX RANGE SCAN | IX_WORKFLOW_NODEBASE_IDIS | 1 | 7 | 1 (0)| 00:00:01 | | 29 | BUFFER SORT | | 1 | 19 | 1 (0)| 00:00:01 | | 30 | INDEX RANGE SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 1 (0)| 00:00:01 | | 31 | INDEX RANGE SCAN | IX_WKFFLND_NW | 1 | 9 | 1 (0)| 00:00:01 | | 32 | FILTER | | | | | | | 33 | NESTED LOOPS | | | | | | | 34 | NESTED LOOPS | | 1 | 188 | 13 (0)| 00:00:01 | | 35 | NESTED LOOPS | | 1 | 109 | 12 (0)| 00:00:01 | | 36 | NESTED LOOPS | | 1 | 103 | 11 (0)| 00:00:01 | | 37 | MERGE JOIN CARTESIAN | | 1 | 38 | 3 (0)| 00:00:01 | | 38 | INDEX RANGE SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 2 (0)| 00:00:01 | | 39 | BUFFER SORT | | 1 | 19 | 1 (0)| 00:00:01 | | 40 | INDEX RANGE SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 1 (0)| 00:00:01 | | 41 | TABLE ACCESS BY INDEX ROWID | WORKFLOW_CURRENTOPERATOR | 1 | 65 | 8 (0)| 00:00:01 | | 42 | INDEX RANGE SCAN | WRKCUOPER_USER_IN2 | 7 | | 2 (0)| 00:00:01 | | 43 | TABLE ACCESS BY INDEX ROWID | WORKFLOW_BASE | 1 | 6 | 1 (0)| 00:00:01 | | 44 | INDEX RANGE SCAN | IX_WFBASE_ID | 1 | | 0 (0)| | | 45 | INDEX UNIQUE SCAN | WORKFLOW_REQUESTID | 1 | | 0 (0)| | | 46 | TABLE ACCESS BY INDEX ROWID | WORKFLOW_REQUESTBASE | 1 | 79 | 1 (0)| 00:00:01 | | 47 | INDEX RANGE SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 2 (0)| 00:00:01 | | 48 | NESTED LOOPS | | 1 | 35 | 3 (0)| 00:00:01 | | 49 | MERGE JOIN CARTESIAN | | 1 | 26 | 2 (0)| 00:00:01 | | 50 | INDEX RANGE SCAN | IX_WORKFLOW_NODEBASE_IDIS | 1 | 7 | 1 (0)| 00:00:01 | | 51 | BUFFER SORT | | 1 | 19 | 1 (0)| 00:00:01 | | 52 | INDEX RANGE SCAN | WORKFLOWCENTERSETTINGDETAIL_I | 1 | 19 | 1 (0)| 00:00:01 | | 53 | INDEX RANGE SCAN | IX_WKFFLND_NW | 1 | 9 | 1 (0)| 00:00:01 | --------------------------------------------------------------------------------------------------------------------------- 270 rows selected. 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（基于sql_id）可以用sql_id创建sql tunning任务，比用sql_text方便很多 FUNCTION CREATE_TUNING_TASK RETURNS VARCHAR2 Argument Name Type In/Out Default? ------------------------------ ----------------------- ------ -------- SQL_ID VARCHAR2 IN PLAN_HASH_VALUE NUMBER IN DEFAULT SCOPE VARCHAR2 IN DEFAULT TIME_LIMIT NUMBER IN DEFAULT TASK_NAME VARCHAR2 IN DEFAULT DESCRIPTION VARCHAR2 IN DEFAULT ———————————————— DECLARE my_task_name VARCHAR2(30); BEGIN my_task_name := DBMS_SQLTUNE.CREATE_TUNING_TASK( SQL_ID => 'xxxx', scope => 'COMPREHENSIVE', time_limit => 60, task_name => 'tunning_task_xxxx', description => 'Task to tune a query on xxxx'); END; / 我们查看此时任务的状态 > select task_name,EXECUTION_START,EXECUTION_END,STATUS from DBA_ADVISOR_LOG where task_name like 'tunning_task_xxxx%'; TASK_NAME EXECUTION_START EXECUTION_END STATUS ------------------------------ ------------------- ------------------- ----------- tunning_task_xxxx INITIAL 执行sql tuning任务 BEGIN DBMS_SQLTUNE.EXECUTE_TUNING_TASK( task_name => 'tunning_task_xxxx' ); END; / 展示sql tunning结果 SET LONG 10000 SET LONGCHUNKSIZE 1000 SET LINESIZE 100 SELECT DBMS_SQLTUNE.REPORT_TUNING_TASK('tunning_task_xxxx') FROM DUAL; 调优后 SQL> SET LONG 10000 SQL> SET LONGCHUNKSIZE 1000 SQL> SET LINESIZE 100 SQL> SELECT DBMS_SQLTUNE.REPORT_TUNING_TASK('tunning_task_ddw7j6yfnw0vz') 2 FROM DUAL; DBMS_SQLTUNE.REPORT_TUNING_TASK('TUNNING_TASK_DDW7J6YFNW0VZ') ---------------------------------------------------------------------------------------------------- GENERAL INFORMATION SECTION ------------------------------------------------------------------------------- Tuning Task Name : tunning_task_ddw7j6yfnw0vz Tuning Task Owner : USERNAME Workload Type : Single SQL Statement Scope : COMPREHENSIVE Time Limit(seconds): 60 Completion Status : COMPLETED Started at : 10/24/2019 16:54:27 Completed at : 10/24/2019 16:54:33 ------------------------------------------------------------------------------- Schema Name: USERNAME SQL ID : a6su7qgyywvn8 SQL Text : ------------------------------------------------------------------------------- FINDINGS SECTION (3 findings) ------------------------------------------------------------------------------- 1- SQL Profile Finding (see explain plans section below) -------------------------------------------------------- A potentially better execution plan was found for this statement. Recommendation (estimated benefit: 27.05%) ------------------------------------------ - Consider accepting the recommended SQL profile. execute dbms_sqltune.accept_sql_profile(task_name => 'tunning_task_ddw7j6yfnw0vz', task_owner => 'USERNAME', replace => TRUE); Validation results ------------------ The SQL profile was tested by executing both its plan and the original plan and measuring their respective execution statistics. A plan may have been only partially executed if the other could be run to completion in less time. Original Plan With SQL Profile % Improved ------------- ---------------- ---------- Completion Status: COMPLETE COMPLETE Elapsed Time(us): 61144 61755 -.99 % CPU Time(us): 21282 20590 3.25 % User I/O Time(us): 0 0 Buffer Gets: 3062 2233 27.07 % Physical Read Requests: 0 0 Physical Write Requests: 0 0 Physical Read Bytes: 0 0 Physical Write Bytes: 0 0 Rows Processed: 5 5 Fetches: 5 5 Executions: 1 1 Notes ----- 1. The original plan was first executed to warm the buffer cache. 2. Statistics for original plan were averaged over next 9 executions. 3. The SQL profile plan was first executed to warm the buffer cache. 4. Statistics for the SQL profile plan were averaged over next 9 executions. 2- Index Finding (see explain plans section below) -------------------------------------------------- The execution plan of this statement can be improved by creating one or more indices. Recommendation (estimated benefit: 97.87%) ------------------------------------------ - Consider running the Access Advisor to improve the physical schema design or creating the recommended index. create index USERNAME.IDX$$_6F3D0001 on USERNAME.WORKFLOWCENTERSETTINGDETAIL("EID","TYPE","TABID"); - Consider running the Access Advisor to improve the physical schema design or creating the recommended index. create index USERNAME.IDX$$_6F3D0002 on USERNAME.WORKFLOW_CURRENTOPERATOR("WORKFLOWID"); Rationale --------- Creating the recommended indices significantly improves the execution plan of this statement. However, it might be preferable to run "Access Advisor" using a representative SQL workload as opposed to a single statement. This will allow to get comprehensive index recommendations which takes into account index maintenance overhead and additional space consumption. 3- Alternative Plan Finding --------------------------- Some alternative execution plans for this statement were found by searching the system's real-time and historical performance data. The following table lists these plans ranked by their average elapsed time. See section "ALTERNATIVE PLANS SECTION" for detailed information on each plan. id plan hash last seen elapsed (s) origin note -- ---------- -------------------- ------------ --------------- ---------------- 1 1019409405 2019-10-24/14:22:29 0.935 Cursor Cache 2 1147966846 2019-10-24/14:14:00 49.312 Cursor Cache 3 1061600654 2019-10-24/14:22:32 7432.859 Cursor Cache Information ----------- - Because no execution history for the Original Plan was found, the SQL Tuning Advisor could not determine if any of these execution plans are superior to it. However, if you know that one alternative plan is better than the Original Plan, you can create a SQL plan baseline for it. This will instruct the Oracle optimizer to pick it over any other choices in the future. execute dbms_sqltune.create_sql_plan_baseline(task_name => 'tunning_task_ddw7j6yfnw0vz', owner_name => 'USERNAME', plan_hash_value => xxxxxxxx); ------------------------------------------------------------------------------- ADDITIONAL INFORMATION SECTION ------------------------------------------------------------------------------- - The optimizer could not merge the view at line ID 6 of the execution plan. The optimizer cannot merge a complex view if its parent query contains a reference to a "ROWNUM" pseudo-column. - The optimizer could not merge the view at line ID 3 of the execution plan. The optimizer cannot merge a view that contains a "ROWNUM" pseudo column. - The optimizer could not merge the view at line ID 1 of the execution plan. The optimizer cannot merge a view that contains a "ROWNUM" pseudo column. - SQL Profile "SYS_SQLPROF_016dfcf4b7e90000" exists for this statement and was ignored during the tuning process. ------------------------------------------------------------------------------- EXPLAIN PLANS SECTION ------------------------------------------------------------------------------- 1- Original With Adjusted Cost ------------------------------ Plan hash value: 3347560359 ---------------------------------------------------------------------------------------------------- ------------------------------- | Id | Operation | Name | Rows | Bytes |T empSpc| Cost (%CPU)| Time | ---------------------------------------------------------------------------------------------------- ------------------------------- | 0 | SELECT STATEMENT | | 1 | 396 | | 94499 (1)| 00:18:54 | |* 1 | VIEW | | 1 | 396 | | 94499 (1)| 00:18:54 | | 2 | COUNT | | | | | | | | 3 | VIEW | | 1 | 383 | | 94499 (1)| 00:18:54 | | 4 | SORT ORDER BY | | 1 | 370 | | 94499 (1)| 00:18:54 | | 5 | COUNT | | | | | | | | 6 | VIEW | | 1 | 370 | | 94632 (1)| 00:18:56 | | 7 | HASH UNIQUE | | 1 | 182 | | 94632 (1)| 00:18:56 | | 8 | CONCATENATION | | | | | | | |* 9 | FILTER | | | | | | | | 10 | NESTED LOOPS | | 37216 | 6614K| | 根据advisor的建议调整查看DB服务器负载已经正常，调优成功

编辑推荐：

返回列表

advisor调优工具优化sql(基于sql_id)

编辑推荐：

相关推荐

excel表格怎样在数字前输入0

excel表格里怎么替换数据

excel表格里面如何插入圆形

excel表格里怎么添加表格数据透视表

excel表格中怎么添加线边框

excel表格里怎样设置条件自动排序

excel表格例怎样导入数据库

Excel表格如何设置数据排序

excel表格里怎么选择性粘贴快捷键

excel表格怎么插入分隔符号

excel表格怎么设置多行多列数据内容排序

Excel表格如何设置行和列相互转换

excel表格连接公式怎么使用

excel表格怎样链接到cad中

雷神推出 MIX PRO II 迷你主机：基于 Ultra 200H，玻璃上盖 + ARGB 灯效

制造商 Musnap 推出彩色墨水屏电纸书 Ocean C：支持手写笔、第三方安卓应用

最新软件资讯

热文推荐

天极热推