使用outline稳固sql执行计划
2012-07-24 22:35
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为指定的sql创建outline
USE_STORED_OUTLINES
Syntax:
USE_STORED_OUTLINES = { TRUE | FALSE | category_name }
this parameters are not initialization parameters, so you cannot set them in a pfile or spfile. However, you can set them using an ALTER SYSTEM statement.重启后需要重新设置。
lau为创建outline的用户，即我们的应用用户。
outline for 绑定变量
1.获取带绑定变量sql的 child_number,hash_value
select child_number,hash_value,address,sql_text from v$sql
where sql_text like 'select * from t where id%';
2.创建outline
begin
dbms_outln.create_outline (
hash_value =>3573770389,
child_number =>0,
category =>'CATE_OUTLINE');
end;
/
USE_STORED_OUTLINES参数在实例重启后需要重新设置，有两种应对方法
1.使用登录触发器为单独的用户设置会话信息
execute immediate 'alter session set use_stored_outlines=cate_outline';
开启类cate_outline。
2.使用启动触发器开启系统级设置
execute immediate 'alter system set use_stored_outlines=cate_outline';
之后的确会开启类cate_outline，使outline生效。
参考：
Using Plan Stability
http://download.oracle.com/docs/cd/B19306_01/server.102/b14211/outlines.htm
USE_STORED_OUTLINES
Syntax:
USE_STORED_OUTLINES = { TRUE | FALSE | category_name }
this parameters are not initialization parameters, so you cannot set them in a pfile or spfile. However, you can set them using an ALTER SYSTEM statement.重启后需要重新设置。
lau为创建outline的用户，即我们的应用用户。
SQL> conn sys/oracle@orcl as sysdba
已连接。
--1.为创建outline用户赋权CREATE ANY OUTLINE
SQL> grant CREATE ANY OUTLINE to lau;
授权成功。
SQL> conn lau/lau@orcl
已连接。
SQL> create table t (id int);
表已创建。
SQL> insert into t select level from dual connect by level <=10000;
已创建10000行。
SQL> commit;
提交完成。
SQL> set autot traceonly
SQL> select * from t where id=1;
执行计划
----------------------------------------------------------
Plan hash value: 1601196873
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 13 | 6 (0)| 00:00:01 |
|* 1 | TABLE ACCESS FULL| T | 1 | 13 | 6 (0)| 00:00:01 |
--------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("ID"=1)
Note
-----
- dynamic sampling used for this statement
统计信息
----------------------------------------------------------
5 recursive calls
0 db block gets
48 consistent gets
0 physical reads
0 redo size
402 bytes sent via SQL*Net to client
385 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
--2.创建两个测试outline
SQL> create or replace outline test_outline1 for category cate_outline
2 on select * from t where id=1;
大纲已创建。
SQL> create or replace outline test_outline2 for category cate_outline
2 on select * from t where id=2;
大纲已创建。
--3.查看该用户下创建的outline。
SQL> col name for a20
SQL> col sql_text for a50
SQL> col used for a10
SQL> set autot off
SQL> set linesize 200
SQL> select name, sql_text ,used,category
2 from user_outlines
3 where category=upper('cate_outline');
NAME SQL_TEXT USED CATEGORY
-------------------- -------------------------------------------------- ---------- ------------------------------
TEST_OUTLINE2 select * from t where id=2 UNUSED CATE_OUTLINE
TEST_OUTLINE1 select * from t where id=1 UNUSED CATE_OUTLINE
--4.使cate_outline下的outline生效
SQL> alter system set USE_STORED_OUTLINES =cate_outline;
系统已更改。
SQL> select name, sql_text ,used,category
2 from user_outlines
3 where category=upper('cate_outline');
NAME SQL_TEXT USED CATEGORY
-------------------- -------------------------------------------------- ---------- ------------------------------
TEST_OUTLINE2 select * from t where id=2 UNUSED CATE_OUTLINE
TEST_OUTLINE1 select * from t where id=1 UNUSED CATE_OUTLINE
SQL> set autot explain
用法: SET AUTOT[RACE] {OFF | ON | TRACE[ONLY]} [EXP[LAIN]] [STAT[ISTICS]]
SQL> set autot on explain
SQL> select * from t where id=1;
ID
----------
1
执行计划
----------------------------------------------------------
Plan hash value: 1601196873
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 13 | 2 (0)| 00:00:01 |
|* 1 | TABLE ACCESS FULL| T | 1 | 13 | 2 (0)| 00:00:01 |
--------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("ID"=1)
Note
-----
- outline "TEST_OUTLINE1" used for this statement --说明已经使用了我们创建的outline.
SQL> select * from t where id=2;
ID
----------
2
执行计划
----------------------------------------------------------
Plan hash value: 1601196873
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 13 | 2 (0)| 00:00:01 |
|* 1 | TABLE ACCESS FULL| T | 1 | 13 | 2 (0)| 00:00:01 |
--------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("ID"=2)
Note
-----
- outline "TEST_OUTLINE2" used for this statement
--以下没有使用outline,因为没有绑定变量。
SQL> select * from t where id=3;
ID
----------
3
执行计划
----------------------------------------------------------
Plan hash value: 1601196873
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 13 | 6 (0)| 00:00:01 |
|* 1 | TABLE ACCESS FULL| T | 1 | 13 | 6 (0)| 00:00:01 |
--------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("ID"=3)
Note
-----
- dynamic sampling used for this statement
--创建索引，验证outline的使用，sql依然使用全表扫描。
SQL> create index ind_t_id on t(id);
索引已创建。
SQL> select * from t where id=1;
ID
----------
1
执行计划
----------------------------------------------------------
Plan hash value: 1601196873
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 13 | 2 (0)| 00:00:01 |
|* 1 | TABLE ACCESS FULL| T | 1 | 13 | 2 (0)| 00:00:01 |
--------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("ID"=1)
Note
-----
- outline "TEST_OUTLINE1" used for this statement
--禁用outline之后，sql使用了索引
SQL> alter system set USE_STORED_OUTLINES =false;
系统已更改。
SQL> select * from t where id=1;
ID
----------
1
执行计划
----------------------------------------------------------
Plan hash value: 3343177607
-----------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
-----------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 13 | 1 (0)| 00:00:01 |
|* 1 | INDEX RANGE SCAN| IND_T_ID | 1 | 13 | 1 (0)| 00:00:01 |
-----------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - access("ID"=1)
Note
-----
- dynamic sampling used for this statementoutline for 绑定变量
1.获取带绑定变量sql的 child_number,hash_value
select child_number,hash_value,address,sql_text from v$sql
where sql_text like 'select * from t where id%';
2.创建outline
begin
dbms_outln.create_outline (
hash_value =>3573770389,
child_number =>0,
category =>'CATE_OUTLINE');
end;
/
SQL> var v_id number;
SQL> exec :v_id :=5;
PL/SQL 过程已成功完成。
提交完成。
SQL> set autot traceonly
SQL> select * from t where id=:v_id;
执行计划
----------------------------------------------------------
Plan hash value: 1601196873
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 100 | 1300 | 7 (15)| 00:00:01 |
|* 1 | TABLE ACCESS FULL| T | 100 | 1300 | 7 (15)| 00:00:01 |
--------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("ID"=TO_NUMBER(:V_ID))
Note
-----
- dynamic sampling used for this statement
统计信息
----------------------------------------------------------
0 recursive calls
0 db block gets
0 consistent gets
0 physical reads
0 redo size
0 bytes sent via SQL*Net to client
0 bytes received via SQL*Net from client
0 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
SQL> col child_number for 999999999999
SQL> col hash_values for 999999999999
SQL> col hash_value for 999999999999
SQL> col address for a20
SQL> col sql_text for a50
SQL> set linesize 200
SQL> select child_number,hash_value,address,sql_text from v$sql
2 where sql_text like 'select * from t where id%';
CHILD_NUMBER HASH_VALUE ADDRESS SQL_TEXT
------------- ------------- -------------------- --------------------------------------------------
0 3573770389 22E58344 select * from t where id=:v_id
SQL> begin
2 dbms_outln.create_outline (
3 hash_value =>3573770389,
4 child_number =>0,
5 category =>'CATE_OUTLINE');
6 end;
7 /
PL/SQL 过程已成功完成。
提交完成。
SQL> select name, sql_text ,used,category
2 from user_outlines
3 where category=upper('cate_outline');
NAME SQL_TEXT USED CATEGORY
-------------------- -------------------------------------------------- ---------- ------------------------------
SYS_OUTLINE_12071817 select * from t where id=:v_id UNUSED CATE_OUTLINE
153216201
SQL> alter system set USE_STORED_OUTLINES =cate_outline;
系统已更改。
SQL> set autot traceonly
SQL> exec :v_id :=1;
PL/SQL 过程已成功完成。
提交完成。
SQL> select * from t where id=:v_id;
执行计划
----------------------------------------------------------
Plan hash value: 1601196873
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 16 | 208 | 6 (0)| 00:00:01 |
|* 1 | TABLE ACCESS FULL| T | 16 | 208 | 6 (0)| 00:00:01 |
--------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("ID"=TO_NUMBER(:V_ID))
Note
-----
- outline "SYS_OUTLINE_12071817153216201" used for this statement
统计信息
----------------------------------------------------------
35 recursive calls
123 db block gets
44 consistent gets
0 physical reads
632 redo size
402 bytes sent via SQL*Net to client
385 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
2 sorts (memory)
0 sorts (disk)
1 rows processed
SQL> exec :v_id :=10;
PL/SQL 过程已成功完成。
提交完成。
SQL> select * from t where id=:v_id;
执行计划
----------------------------------------------------------
Plan hash value: 1601196873
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 16 | 208 | 6 (0)| 00:00:01 |
|* 1 | TABLE ACCESS FULL| T | 16 | 208 | 6 (0)| 00:00:01 |
--------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("ID"=TO_NUMBER(:V_ID))
Note
-----
- outline "SYS_OUTLINE_12071817153216201" used for this statement
统计信息
----------------------------------------------------------
0 recursive calls
0 db block gets
24 consistent gets
0 physical reads
0 redo size
402 bytes sent via SQL*Net to client
385 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
SQL> create index ind_t_id on t(id);
索引已创建。
SQL> comment on column t.id is 'dddd';
注释已创建。
SQL> select * from t where id=:v_id;
执行计划
----------------------------------------------------------
Plan hash value: 1601196873
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 16 | 208 | 6 (0)| 00:00:01 |
|* 1 | TABLE ACCESS FULL| T | 16 | 208 | 6 (0)| 00:00:01 |
--------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("ID"=TO_NUMBER(:V_ID))
Note
-----
- outline "SYS_OUTLINE_12071817153216201" used for this statement
统计信息
----------------------------------------------------------
1 recursive calls
0 db block gets
24 consistent gets
0 physical reads
0 redo size
402 bytes sent via SQL*Net to client
385 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
SQL> alter system set use_stored_outlines=false;
系统已更改。
SQL> select * from t where id=:v_id;
执行计划
----------------------------------------------------------
Plan hash value: 3343177607
-----------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
-----------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 100 | 1300 | 1 (0)| 00:00:01 |
|* 1 | INDEX RANGE SCAN| IND_T_ID | 100 | 1300 | 1 (0)| 00:00:01 |
-----------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - access("ID"=TO_NUMBER(:V_ID))
Note
-----
- dynamic sampling used for this statement
统计信息
----------------------------------------------------------
13 recursive calls
0 db block gets
30 consistent gets
4 physical reads
0 redo size
402 bytes sent via SQL*Net to client
385 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processedUSE_STORED_OUTLINES参数在实例重启后需要重新设置，有两种应对方法
1.使用登录触发器为单独的用户设置会话信息
SQL> conn lau/lau@oralife
已连接。
SQL> create or replace trigger tr_login
2 after logon on database
3 declare
4 v_username varchar2(30);
5 begin
6 select SYS_CONTEXT('USERENV','SESSION_USER') into v_username from dual;
7 if v_username = 'SCOTT' then
8 execute immediate 'alter session set nls_date_format=''yyyy/mm/dd hh24:mi:ss''';
9 end if;
10 exception
11 when others then
12 null;
13 end;
14 /
触发器已创建
SQL> select sysdate from dual;
SYSDATE
--------------
25-7月 -12
SQL> conn scott/tiger@oralife
已连接。
SQL> select sysdate from dual;
SYSDATE
-------------------
2012/07/25 20:26:10在登录触发器中为特定的用户添加execute immediate 'alter session set use_stored_outlines=cate_outline';
开启类cate_outline。
2.使用启动触发器开启系统级设置
SQL> conn sys/oracle@oralife as sysdba 已连接。 SQL> create or replace trigger tr_login 2 after STARTUP on database 3 declare 4 begin 5 execute immediate 'alter system set nls_date_format=''yyyy/mm/dd hh24:mi:ss'''; 6 exception 7 when others then 8 null; 9 end; 10 / 触发器已创建 SQL> select sysdate from dual; SYSDATE -------------- 25-7月 -12 --重启实例后，以上的设置并没有生效，但是添加 --execute immediate 'alter system set use_stored_outlines=cate_outline'; --之后的确会开启类cate_outline，使outline生效。 SQL> select sysdate from dual; SYSDATE -------------- 25-7月 -12 --没有生效重启实例后，以上的设置并没有生效，但是将其替换为
execute immediate 'alter system set use_stored_outlines=cate_outline';
之后的确会开启类cate_outline，使outline生效。
参考：
Using Plan Stability
http://download.oracle.com/docs/cd/B19306_01/server.102/b14211/outlines.htm
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