【DB笔试面试604】在Oracle中，存储概要（Stored Outline）的作用是什么？

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♣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') 99100Note101-----102   - dynamic sampling used for this statement (level=2)103104105Statistics106----------------------------------------------------------107          7  recursive calls108          0  db block gets109        170  consistent gets110          0  physical reads111          0  redo size112        333  bytes sent via SQL*Net to client113        508  bytes received via SQL*Net from client114          1  SQL*Net roundtrips to/from client115          0  sorts (memory)116          0  sorts (disk)117          0  rows processed118119LHR@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';121122Outline created.123124LHR@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';125126Outline created.127128LHR@test> select name,USED,sql_text from dba_outlines where name like '%TB_LHR_20160518%';129130NAME                           USED   SQL_TEXT131------------------------------ ------ --------------------------------------------------------------------------------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='T134135LHR@test> select name,HINT from dba_outline_hints where JOIN_POS=1 and name like '%TB_LHR_20160518%';136137NAME                           HINT138------------------------------ --------------------------------------------------------------------------------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$1")141142LHR@test> UPDATE OUTLN.OL$ 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');1431442 rows updated.145146LHR@test> commit;147148Commit complete.149150LHR@test> select name,USED,sql_text from dba_outlines where name like '%TB_LHR_20160518%';151152NAME                           USED   SQL_TEXT153------------------------------ ------ --------------------------------------------------------------------------------154TB_LHR_20160518_1              UNUSED select /*+full(TB_LHR_20160518)*/ owner from TB_LHR_20160518 where table_name='T155TB_LHR_20160518_2              UNUSED select owner from TB_LHR_20160518 where table_name='TB_LHR_20160518'156157LHR@test> SELECT NAME,HINT FROM DBA_OUTLINE_HINTS WHERE JOIN_POS=1 AND NAME LIKE '%TB_LHR_20160518%';158159NAME                           HINT160------------------------------ --------------------------------------------------------------------------------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")163164LHR@test> SET AUTOTRACE ON;165LHR@test> alter system set use_stored_outlines=true;166167System altered.168169LHR@test> select owner from TB_LHR_20160518 where table_name='TB_LHR_20160518';170171no rows selected172173174Execution Plan175----------------------------------------------------------176Plan hash value: 1750418716177178-------------------------------------------------------------------------------------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-------------------------------------------------------------------------------------184185Predicate Information (identified by operation id):186---------------------------------------------------187188   1 - filter("TABLE_NAME"='TB_LHR_20160518')189190Note191-----192   - outline "TB_LHR_20160518_2" used for this statement193194195Statistics196----------------------------------------------------------197         34  recursive calls198        147  db block gets199        125  consistent gets200          0  physical reads201        624  redo size202        333  bytes sent via SQL*Net to client203        508  bytes received via SQL*Net from client204          1  SQL*Net roundtrips to/from client205          2  sorts (memory)206          0  sorts (disk)207          0  rows processed208209LHR@test> select /*+full(TB_LHR_20160518)*/ owner from TB_LHR_20160518 where table_name='TB_LHR_20160518';210211no rows selected212213214Execution Plan215----------------------------------------------------------216Plan hash value: 2186742855217218---------------------------------------------------------------------------------------------------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---------------------------------------------------------------------------------------------------225226Predicate Information (identified by operation id):227---------------------------------------------------228229   2 - access("TABLE_NAME"='TB_LHR_20160518')230231Note232-----233   - outline "TB_LHR_20160518_1" used for this statement234235236Statistics237----------------------------------------------------------238         34  recursive calls239        147  db block gets240         24  consistent gets241          0  physical reads242        584  redo size243        333  bytes sent via SQL*Net to client244        508  bytes received via SQL*Net from client245          1  SQL*Net roundtrips to/from client246          2  sorts (memory)247          0  sorts (disk)248          0  rows processedcreate user lhr identified by lhr;

  3User created.

  5SYS@test> grant dba to lhr;

  7Grant succeeded.

  9SYS@test> grant create any outline,alter any outline,DROP ANY OUTLINE to lhr;

 11Grant succeeded.

 13SYS@test> grant all on OL$HINTS to lhr;

 15Grant succeeded.

 17SYS@test> conn lhr/lhr
 18Connected.
 19LHR@test> select * from v$version;

 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

 29LHR@test> create table TB_LHR_20160518 as select * from dba_tables;

 31Table created.

 33LHR@test> create index idx_TB_LHR_20160518 on TB_LHR_20160518(TABLE_NAME);

 35Index created.

 37LHR@test> SET AUTOTRACE ON;
 38LHR@test> select owner from TB_LHR_20160518 where table_name='TB_LHR_20160518';

 40no rows selected

 43Execution Plan
 44----------------------------------------------------------
 45Plan hash value: 2186742855

 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---------------------------------------------------------------------------------------------------

 55Predicate Information (identified by operation id):
 56---------------------------------------------------
  2 - access("TABLE_NAME"='TB_LHR_20160518')

 60Note
 61-----
  - dynamic sampling used for this statement (level=2)

 65Statistics
 66----------------------------------------------------------
 recursive calls
 db block gets
 consistent gets
 physical reads
 redo size
 bytes sent via SQL*Net to client
 bytes received via SQL*Net from client
 SQL*Net roundtrips to/from client
 sorts (memory)
 sorts (disk)
 rows processed

 79LHR@test> select /*+full(TB_LHR_20160518)*/ owner from TB_LHR_20160518 where table_name='TB_LHR_20160518';

 81no rows selected

 84Execution Plan
 85----------------------------------------------------------
 86Plan hash value: 1750418716

 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-------------------------------------------------------------------------------------

 95Predicate Information (identified by operation id):
 96---------------------------------------------------
  1 - filter("TABLE_NAME"='TB_LHR_20160518')

100Note
101-----
  - dynamic sampling used for this statement (level=2)

105Statistics
106----------------------------------------------------------
 recursive calls
 db block gets
 consistent gets
 physical reads
 redo size
 bytes sent via SQL*Net to client
 bytes received via SQL*Net from client
 SQL*Net roundtrips to/from client
 sorts (memory)
 sorts (disk)
 rows processed

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';

122Outline created.

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';

126Outline created.

128LHR@test> select name,USED,sql_text from dba_outlines where name like '%TB_LHR_20160518%';

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

135LHR@test> select name,HINT from dba_outline_hints where JOIN_POS=1 and name like '%TB_LHR_20160518%';

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")

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');
rows updated.

146LHR@test> commit;

148Commit complete.

150LHR@test> select name,USED,sql_text from dba_outlines where name like '%TB_LHR_20160518%';

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'

157LHR@test> SELECT NAME,HINT FROM DBA_OUTLINE_HINTS WHERE JOIN_POS=1 AND NAME LIKE '%TB_LHR_20160518%';

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")

164LHR@test> SET AUTOTRACE ON;
165LHR@test> alter system set use_stored_outlines=true;

167System altered.

169LHR@test> select owner from TB_LHR_20160518 where table_name='TB_LHR_20160518';

171no rows selected

174Execution Plan
175----------------------------------------------------------
176Plan hash value: 1750418716

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-------------------------------------------------------------------------------------

185Predicate Information (identified by operation id):
186---------------------------------------------------
  1 - filter("TABLE_NAME"='TB_LHR_20160518')

190Note
191-----
  - outline "TB_LHR_20160518_2" used for this statement

195Statistics
196----------------------------------------------------------
 recursive calls
 db block gets
 consistent gets
 physical reads
 redo size
 bytes sent via SQL*Net to client
 bytes received via SQL*Net from client
 SQL*Net roundtrips to/from client
 sorts (memory)
 sorts (disk)
 rows processed

209LHR@test> select /*+full(TB_LHR_20160518)*/ owner from TB_LHR_20160518 where table_name='TB_LHR_20160518';

211no rows selected

214Execution Plan
215----------------------------------------------------------
216Plan hash value: 2186742855

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---------------------------------------------------------------------------------------------------

226Predicate Information (identified by operation id):
227---------------------------------------------------
  2 - access("TABLE_NAME"='TB_LHR_20160518')

231Note
232-----
  - outline "TB_LHR_20160518_1" used for this statement

236Statistics
237----------------------------------------------------------
 recursive calls
 db block gets
 consistent gets
 physical reads
 redo size
 bytes sent via SQL*Net to client
 bytes received via SQL*Net from client
 SQL*Net roundtrips to/from client
 sorts (memory)
 sorts (disk)
 rows processed