♣题目 部分
在Oracle中，存储概要（Stored Outline）的作用是什么？
♣答案部分
OUTLINE的原理是将调好的执行计划（一系列的Hint）保存起来，然后使用该效率高的执行计划替换之前效率低下的执行计划，从而使得当系统每次执行该SQL时，都会使用已存储的执行计划来执行。所以，可以在不改变已有系统SQL的情况下达到改变其执行计划的目的。OUTLINE方式是通过存储Hint的方式来达到执行计划的稳定与改变。当发现低效SQL之后，可以使用Hint优化它，对于SQL代码可以修改的情况，直接修改SQL代码加上Hint即可。
Oracle在Outline的表中保存了SQL的Hint，当执行SQL时，Oracle会使用Outline中的Hint来为SQL生成执行计划。
Ø使用OutLine的步骤：
（1）生成新SQL和老SQL的2个Outline
（2）交换两个SQL的提示信息
（3）ON LOGON触发器设定session的CATEGORY（自定义类别）
SQL命令行为：SQL>alter session set use_stored_outlines=special;
Ouline使用演示：
1SYS@test> create user lhr identified by lhr;
2
3User created.
4
5SYS@test> grant dba to lhr;
6
7Grant succeeded.
8
9SYS@test> grant create any outline,alter any outline,DROP ANY OUTLINE to lhr;
10
11Grant succeeded.
12
13SYS@test> grant all on OL$HINTS to lhr;
14
15Grant succeeded.
16
17SYS@test> conn lhr/lhr
18Connected.
19LHR@test> select * from v$version;
20
21BANNER
22--------------------------------------------------------------------------------
23Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
24PL/SQL Release 11.2.0.4.0 - Production
25CORE 11.2.0.4.0 Production
26TNS for IBM/AIX RISC System/6000: Version 11.2.0.4.0 - Production
27NLSRTL Version 11.2.0.4.0 - Production
28
29LHR@test> create table TB_LHR_20160518 as select * from dba_tables;
30
31Table created.
32
33LHR@test> create index idx_TB_LHR_20160518 on TB_LHR_20160518(TABLE_NAME);
34
35Index created.
36
37LHR@test> SET AUTOTRACE ON;
38LHR@test> select owner from TB_LHR_20160518 where table_name='TB_LHR_20160518';
39
40no rows selected
41
42
43Execution Plan
44----------------------------------------------------------
45Plan hash value: 2186742855
46
47---------------------------------------------------------------------------------------------------
48| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
49---------------------------------------------------------------------------------------------------
50| 0 | SELECT STATEMENT | | 1 | 34 | 1 (0)| 00:00:01 |
51| 1 | TABLE ACCESS BY INDEX ROWID| TB_LHR_20160518 | 1 | 34 | 1 (0)| 00:00:01 |
52|* 2 | INDEX RANGE SCAN | IDX_TB_LHR_20160518 | 1 | | 1 (0)| 00:00:01 |
53---------------------------------------------------------------------------------------------------
54
55Predicate Information (identified by operation id):
56---------------------------------------------------
57
58 2 - access("TABLE_NAME"='TB_LHR_20160518')
59
60Note
61-----
62 - dynamic sampling used for this statement (level=2)
63
64
65Statistics
66----------------------------------------------------------
67 11 recursive calls
68 0 db block gets
69 72 consistent gets
70 8 physical reads
71 0 redo size
72 333 bytes sent via SQL*Net to client
73 508 bytes received via SQL*Net from client
74 1 SQL*Net roundtrips to/from client
75 0 sorts (memory)
76 0 sorts (disk)
77 0 rows processed
78
79LHR@test> select /*+full(TB_LHR_20160518)*/ owner from TB_LHR_20160518 where table_name='TB_LHR_20160518';
80
81no rows selected
82
83
84Execution Plan
85----------------------------------------------------------
86Plan hash value: 1750418716
87
88-------------------------------------------------------------------------------------
89| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
90-------------------------------------------------------------------------------------
91| 0 | SELECT STATEMENT | | 1 | 34 | 31 (0)| 00:00:01 |
92|* 1 | TABLE ACCESS FULL| TB_LHR_20160518 | 1 | 34 | 31 (0)| 00:00:01 |
93-------------------------------------------------------------------------------------
94
95Predicate Information (identified by operation id):
96---------------------------------------------------
97
98 1 - filter("TABLE_NAME"='TB_LHR_20160518')
99
100Note
101-----
102 - dynamic sampling used for this statement (level=2)
103
104
105Statistics
106----------------------------------------------------------
107 7 recursive calls
108 0 db block gets
109 170 consistent gets
110 0 physical reads
111 0 redo size
112 333 bytes sent via SQL*Net to client
113 508 bytes received via SQL*Net from client
114 1 SQL*Net roundtrips to/from client
115 0 sorts (memory)
116 0 sorts (disk)
117 0 rows processed
118
119LHR@test> set autotrace off;
120LHR@test> create or replace outline TB_LHR_20160518_1 on select owner from TB_LHR_20160518 where table_name='TB_LHR_20160518';
121
122Outline created.
123
124LHR@test> create or replace outline TB_LHR_20160518_2 on select /*+full(TB_LHR_20160518)*/ owner from TB_LHR_20160518 where table_name='TB_LHR_20160518';
125
126Outline created.
127
128LHR@test> select name,USED,sql_text from dba_outlines where name like '%TB_LHR_20160518%';
129
130NAME USED SQL_TEXT
131------------------------------ ------ --------------------------------------------------------------------------------
132TB_LHR_20160518_1 UNUSED select owner from TB_LHR_20160518 where table_name='TB_LHR_20160518'
133TB_LHR_20160518_2 UNUSED select /*+full(TB_LHR_20160518)*/ owner from TB_LHR_20160518 where table_name='T
134
135LHR@test> select name,HINT from dba_outline_hints where JOIN_POS=1 and name like '%TB_LHR_20160518%';
136
137NAME HINT
138------------------------------ --------------------------------------------------------------------------------
139TB_LHR_20160518_1 INDEX_RS_ASC(@"SEL$1" "TB_LHR_20160518"@"SEL$1" ("TB_LHR_20160518"."TABLE_NAME")
140TB_LHR_20160518_2 FULL(@"SEL$1" "TB_LHR_20160518"@"SEL$1")
141
142LHR@test> UPDATE OUTLN.OL$ SET OL_NAME=DECODE(OL_NAME,'TB_LHR_20160518_2','TB_LHR_20160518_1','TB_LHR_20160518_1','TB_LHR_20160518_2') WHERE OL_NAME IN ('TB_LHR_20160518_1','TB_LHR_20160518_2');
143
1442 rows updated.
145
146LHR@test> commit;
147
148Commit complete.
149
150LHR@test> select name,USED,sql_text from dba_outlines where name like '%TB_LHR_20160518%';
151
152NAME USED SQL_TEXT
153------------------------------ ------ --------------------------------------------------------------------------------
154TB_LHR_20160518_1 UNUSED select /*+full(TB_LHR_20160518)*/ owner from TB_LHR_20160518 where table_name='T
155TB_LHR_20160518_2 UNUSED select owner from TB_LHR_20160518 where table_name='TB_LHR_20160518'
156
157LHR@test> SELECT NAME,HINT FROM DBA_OUTLINE_HINTS WHERE JOIN_POS=1 AND NAME LIKE '%TB_LHR_20160518%';
158
159NAME HINT
160------------------------------ --------------------------------------------------------------------------------
161TB_LHR_20160518_1 INDEX_RS_ASC(@"SEL$1" "TB_LHR_20160518"@"SEL$1" ("TB_LHR_20160518"."TABLE_NAME")
162TB_LHR_20160518_2 FULL(@"SEL$1" "TB_LHR_20160518"@"SEL$1")
163
164LHR@test> SET AUTOTRACE ON;
165LHR@test> alter system set use_stored_outlines=true;
166
167System altered.
168
169LHR@test> select owner from TB_LHR_20160518 where table_name='TB_LHR_20160518';
170
171no rows selected
172
173
174Execution Plan
175----------------------------------------------------------
176Plan hash value: 1750418716
177
178-------------------------------------------------------------------------------------
179| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
180-------------------------------------------------------------------------------------
181| 0 | SELECT STATEMENT | | 89 | 3026 | 31 (0)| 00:00:01 |
182|* 1 | TABLE ACCESS FULL| TB_LHR_20160518 | 89 | 3026 | 31 (0)| 00:00:01 |
183-------------------------------------------------------------------------------------
184
185Predicate Information (identified by operation id):
186---------------------------------------------------
187
188 1 - filter("TABLE_NAME"='TB_LHR_20160518')
189
190Note
191-----
192 - outline "TB_LHR_20160518_2" used for this statement
193
194
195Statistics
196----------------------------------------------------------
197 34 recursive calls
198 147 db block gets
199 125 consistent gets
200 0 physical reads
201 624 redo size
202 333 bytes sent via SQL*Net to client
203 508 bytes received via SQL*Net from client
204 1 SQL*Net roundtrips to/from client
205 2 sorts (memory)
206 0 sorts (disk)
207 0 rows processed
208
209LHR@test> select /*+full(TB_LHR_20160518)*/ owner from TB_LHR_20160518 where table_name='TB_LHR_20160518';
210
211no rows selected
212
213
214Execution Plan
215----------------------------------------------------------
216Plan hash value: 2186742855
217
218---------------------------------------------------------------------------------------------------
219| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
220---------------------------------------------------------------------------------------------------
221| 0 | SELECT STATEMENT | | 89 | 3026 | 6 (0)| 00:00:01 |
222| 1 | TABLE ACCESS BY INDEX ROWID| TB_LHR_20160518 | 89 | 3026 | 6 (0)| 00:00:01 |
223|* 2 | INDEX RANGE SCAN | IDX_TB_LHR_20160518 | 36 | | 1 (0)| 00:00:01 |
224---------------------------------------------------------------------------------------------------
225
226Predicate Information (identified by operation id):
227---------------------------------------------------
228
229 2 - access("TABLE_NAME"='TB_LHR_20160518')
230
231Note
232-----
233 - outline "TB_LHR_20160518_1" used for this statement
234
235
236Statistics
237----------------------------------------------------------
238 34 recursive calls
239 147 db block gets
240 24 consistent gets
241 0 physical reads
242 584 redo size
243 333 bytes sent via SQL*Net to client
244 508 bytes received via SQL*Net from client
245 1 SQL*Net roundtrips to/from client
246 2 sorts (memory)
247 0 sorts (disk)
248 0 rows processed
