SQL Tuning Advision是Oracle提供的一個功能包，可以針對有性能問題的SQL給出優化建議。可以作為調優的輔助手段。

建立測試表和索引
create table t_1 as select * from dba_objects;
create table t_2 as select * from dba_tables;
create index idx_t_2_ts on t_2(tablespace_name);

begin
? dbms_stats.gather_table_stats(ownname => user,tabname => 'T_1',cascade => true);
? dbms_stats.gather_table_stats(ownname => user,tabname => 'T_2',cascade => true);
end;
/

假設的SQL。 這些語句運行很慢，需要優化
-- stmt 1
select t2.*
? from t_1 t1, t_2 t2
?where t1.owner = t2.owner
?? and t1.object_name = t2.table_name
?? and t2.blocks > 10
?? and t2.tablespace_name = 'USERS';

-- stmt 2
select t1.* from t_1 t1 where t1.object_type = 'TABLE';

使用SQL Tuning Advisor，察看系統提供的優化方案

Single SQL Statement

當僅僅需要察看單條語句的時候，可以直接把SQL作為參數創建一個Task

?

-- drop a sql tuning task
begin
dbms_sqltune.drop_tuning_task(task_name => 'my_sql_tuning_task');
end;
/

-- create a sql tuning task
declare
l_task_name varchar2(30);
l_sqltext clob;
begin
l_sqltext := --
'select t2.*
from t_1 t1, t_2 t2
where t1.owner = t2.owner
and t1.object_name = t2.table_name
and t2.blocks > :p1
and t2.tablespace_name = :p2';
l_task_name := dbms_sqltune.create_tuning_task --
(sql_text => l_sqltext,
bind_list => sql_binds(anydata.ConvertNumber(10),
anydata.ConvertVarchar2('USERS')),
user_name => user,
scope => dbms_sqltune.SCOPE_COMPREHENSIVE,
time_limit => 60,
task_name => 'my_sql_tuning_task');
end;
/

select l.task_name,l.status from dba_advisor_log l where l.owner = user;

-- execute a sql tuning task
begin
dbms_sqltune.execute_tuning_task(task_name => 'my_sql_tuning_task');
end;
/

-- check the running progress
select p.sofar, p.totalwork
from v$advisor_progress p, dba_advisor_log l
where p.task_id = l.task_id
and l.task_name = 'my_sql_tuning_task';

-- display the result
set long 1000000
set linesize 100
select dbms_sqltune.report_tuning_task('my_sql_tuning_task') from dual;

節選部分結果
-------------------------------------------------------------------------------
FINDINGS SECTION (1 finding)
-------------------------------------------------------------------------------
?
1- 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: 100%)
? ----------------------------------------
? - Consider running the Access Advisor to improve the physical schema design
??? or creating the recommended index.
??? create index T2_1_12_6_A.IDX$$_7DCA0001 on
??? T2_1_12_6_A.T_2('TABLESPACE_NAME','BLOCKS');
?
? - Consider running the Access Advisor to improve the physical schema design
??? or creating the recommended index.
??? create index T2_1_12_6_A.IDX$$_7DCA0002 on
??? T2_1_12_6_A.T_1('OWNER','OBJECT_NAME');
?
? 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.
?
-------------------------------------------------------------------------------
EXPLAIN PLANS SECTION
-------------------------------------------------------------------------------
?
1- Original
-----------
Plan hash value: 3244836478
?
--------------------------------------------------------------------------------
| Id? | Operation??????????????????? | Name?????? | Rows? | Bytes | Cost (%CPU)|
--------------------------------------------------------------------------------
|?? 0 | SELECT STATEMENT???????????? |??????????? |???? 1 |?? 250 |?? 364?? (2)|
|*? 1 |? HASH JOIN?????????????????? |??????????? |???? 1 |?? 250 |?? 364?? (2)|
|*? 2 |?? TABLE ACCESS BY INDEX ROWID| T_2??????? |???? 1 |?? 216 |???? 3?? (0)|
|*? 3 |??? INDEX RANGE SCAN????????? | IDX_T_2_TS |??? 43 |?????? |???? 1?? (0)|
|?? 4 |?? TABLE ACCESS FULL????????? | T_1??????? |?? 148K|? 4946K|?? 360?? (1)|
--------------------------------------------------------------------------------
?
Predicate Information (identified by operation id):
---------------------------------------------------
?
?? 1 - access("T1"."OWNER"="T2"."OWNER" AND "T1"."OBJECT_NAME"="T2"."TABLE_NAME"
?? 2 - filter("T2"."BLOCKS">:P1)
?? 3 - access("T2"."TABLESPACE_NAME"=:P2)
?
2- Using New Indices
--------------------
Plan hash value: 1060650565
?
--------------------------------------------------------------------------------
| Id? | Operation??????????????????? | Name?????????? | Rows? | Bytes | Cost (%C
--------------------------------------------------------------------------------
|?? 0 | SELECT STATEMENT???????????? |??????????????? |???? 1 |?? 250 |???? 3
|?? 1 |? NESTED LOOPS??????????????? |??????????????? |???? 1 |?? 250 |???? 3
|?? 2 |?? TABLE ACCESS BY INDEX ROWID| T_2??????????? |???? 1 |?? 216 |???? 2
|*? 3 |??? INDEX RANGE SCAN????????? | IDX$$_7DCA0001 |???? 1 |?????? |???? 1
|*? 4 |?? INDEX RANGE SCAN?????????? | IDX$$_7DCA0002 |???? 1 |??? 34 |???? 1
--------------------------------------------------------------------------------
?
Predicate Information (identified by operation id):
---------------------------------------------------
?
?? 3 - access("T2"."TABLESPACE_NAME"=:P2 AND "T2"."BLOCKS">:P1 AND "T2"."BLOCKS"
????????????? NOT NULL)
?? 4 - access("T1"."OWNER"="T2"."OWNER" AND "T1"."OBJECT_NAME"="T2"."TABLE_NAME"
?
-------------------------------------------------------------------------------

SQL Tuning Set
當需要對多條語句進行察看的時候，可以使用STS。


STS可以從多種數據源(CursorCache, AWR, STS)獲取SQL，這里我們從Cache中取得我們關心的幾條。
SQL> select sql_id, sql_text from v$sql where lower(sql_text) like 'select t_.*%';
?
SQL_ID??????? SQL_TEXT
------------- --------------------------------------------------------------------------------
7rucbfq8vcr7d select t1.*?? from t_1 t1??? where t1.object_type = 'TABLE'
588rxmp05xt7g select t2.*?? from t_1 t1, t_2 t2? where t1.owner = t2.owner??? and t1.object_na

STS中實際包含的是一些sys.sqlset_row對象，他的屬性可以作為篩選的條件
SQL> desc dbms_sqltune.select_cursor_cache
Parameter???????? Type?????? Mode Default?
----------------- ---------- ---- --------
(RESULT)????????? SYS.SQLSET??????????????
BASIC_FILTER????? VARCHAR2?? IN?? Y???????
OBJECT_FILTER???? VARCHAR2?? IN?? Y???????
RANKING_MEASURE1? VARCHAR2?? IN?? Y???????
RANKING_MEASURE2? VARCHAR2?? IN?? Y???????
RANKING_MEASURE3? VARCHAR2?? IN?? Y???????
RESULT_PERCENTAGE NUMBER???? IN?? Y???????
RESULT_LIMIT????? NUMBER???? IN?? Y???????
ATTRIBUTE_LIST??? VARCHAR2?? IN?? Y???????
-- preview the STS contents
select t.*
? from table(dbms_sqltune.select_cursor_cache('sql_id in (''588rxmp05xt7g'',''7rucbfq8vcr7d'')')) t;

找到我們關心的sql_id之后，用這個條件構造STS

?

-- create a STS
begin
dbms_sqltune.create_sqlset(sqlset_name => 'my_sts');
end;
/

-- load STS using cursor cache
declare
l_cur dbms_sqltune.sqlset_cursor;
begin
open l_cur for
select value(t)
from table(dbms_sqltune.select_cursor_cache('sql_id in (''588rxmp05xt7g'',''7rucbfq8vcr7d'')')) t;

dbms_sqltune.load_sqlset(sqlset_name => 'my_sts', populate_cursor => l_cur);
end;
/

-- display contents of STS
select * from table(dbms_sqltune.select_sqlset('my_sts'));

-- drop a sql tuning task
begin
dbms_sqltune.drop_tuning_task(task_name => 'my_sql_tuning_task');
end;
/

-- create a sql tuning task by using STS
declare
l_task_name varchar2(30);
l_sqltext clob;
begin
l_task_name := dbms_sqltune.create_tuning_task --
(sqlset_name => 'my_sts',
scope => dbms_sqltune.SCOPE_COMPREHENSIVE,
time_limit => 60,
task_name => 'my_sql_tuning_task');
end;
/

繼續后面的執行和察看步驟（略）

轉載于:https://www.cnblogs.com/wait4friend/archive/2012/02/01/2334614.html

總結

以上是生活随笔為你收集整理的SQL Tuning Advisor简单使用的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。