兩列複合索引中(交換索引中列的順序)，選索引的原則是?因為索引名字ascii碼小？

psufnxk2000發表於2014-05-22
索引ASCII
對於一個兩列的複合索引，where條件中都是用 “=” 號 和 and,  選取索引時，為什麼選擇 索引名 ascii碼小的？？

在天師 老托拉呱 的指點下，  不用動態取樣+cbo, 還是一樣的結果 。  用rbo的話，會一直有同一個。但是 不曉得 cbo的原因 。


最終在 天師的指示下看到    Handling of equally ranked (RBO) or costed (CBO) indexes (Doc ID 73167.1)

create table t11 as select * from dba_objects;

create index idx_1 on t11(object_id,object_name);

create index idx_2 on t11(object_name,object_id);

Alter session set events '10053 trace name context forever, level 1';

select * from t11 where object_name='ICOL$' and object_id=20;
Alter session set events '10053 trace name context off';


 Access Path: TableScan
    Cost:  139.65  Resp: 139.65  Degree: 0
      Cost_io: 139.00  Cost_cpu: 20044626
      Resp_io: 139.00  Resp_cpu: 20044626
  Access Path: index (AllEqRange)
    Index: IDX_1
    resc_io: 2.00  resc_cpu: 15683
    ix_sel: 1.6000e-05  ix_sel_with_filters: 1.6000e-05
    Cost: 2.00  Resp: 2.00  Degree: 1
  Access Path: index (AllEqRange)
    Index: IDX_2
    resc_io: 2.00  resc_cpu: 15683
    ix_sel: 1.6000e-05  ix_sel_with_filters: 1.6000e-05
    Cost: 2.00  Resp: 2.00  Degree: 1
  ****** trying bitmap/domain indexes ******
  ****** finished trying bitmap/domain indexes ******
  Best:: AccessPath: IndexRange  Index: IDX_1
         Cost: 2.00  Degree: 1  Resp: 2.00  Card: 5.75  Bytes: 
***************************************
OPTIMIZER STATISTICS AND COMPUTATIONS
***************************************
GENERAL PLANS
***************************************
Considering cardinality-based initial join order.
Permutations for Starting Table :0
***********************
Join order[1]:  T11[T11]#0
***********************
Best so far: Table#: 0  cost: 2.0005  card: 5.7533  bytes: 1062
(newjo-stop-1) k:0, spcnt:0, perm:1, maxperm:80000
*********************************
Number of join permutations tried: 1
*********************************
Final - All Rows Plan:  Best join order: 1
  Cost: 2.0005  Degree: 1  Card: 6.0000  Bytes: 1062
  Resc: 2.0005  Resc_io: 2.0000  Resc_cpu: 15683
  Resp: 2.0005  Resp_io: 2.0000  Resc_cpu: 15683
kkoipt: Query block SEL$1 (#0)
******* UNPARSED QUERY IS *******
SELECT "T11"."OWNER" "OWNER","T11"."OBJECT_NAME" "OBJECT_NAME","T11"."SUBOBJECT_NAME" "SUBOBJECT_NAME","T11"."OBJECT_ID" "OBJECT_ID","T11"."DATA_OBJECT_ID" "DATA_OBJECT_ID","T11"."OBJECT_TYPE" "OBJECT_TYPE","T11"."CREATED" "CREATED","T11"."LAST_DDL_TIME" "LAST_DDL_TIME","T11"."TIMESTAMP" "TIMESTAMP","T11"."STATUS" "STATUS","T11"."TEMPORARY" "TEMPORARY","T11"."GENERATED" "GENERATED","T11"."SECONDARY" "SECONDARY" FROM "SONG"."T11" "T11" WHERE "T11"."OBJECT_NAME"='ICOL$' AND "T11"."OBJECT_ID"=20
kkoqbc-subheap (delete addr=0x2b271cfabe38, in-use=17008, alloc=18400)
kkoqbc-end
          : call(in-use=37416, alloc=65448), compile(in-use=48936, alloc=50504)
apadrv-end: call(in-use=37416, alloc=65448), compile(in-use=49808, alloc=50504)
 
sql_id=7a6qgwc26kkq4.
Current SQL statement for this session:
select * from t11 where object_name='ICOL$' and object_id=20
 
============
Plan Table
============
-----------------------------------------------+-----------------------------------+
| Id  | Operation                    | Name    | Rows  | Bytes | Cost  | Time      |
-----------------------------------------------+-----------------------------------+
| 0   | SELECT STATEMENT             |         |       |       |     2 |           |
| 1   |  TABLE ACCESS BY INDEX ROWID | T11     |     6 |  1062 |     2 |  00:00:01 |
| 2   |   INDEX RANGE SCAN           | IDX_1   |     1 |       |     1 |  00:00:01 |
-----------------------------------------------+-----------------------------------+
Predicate Information:
----------------------
2 - access("OBJECT_ID"=20 AND "OBJECT_NAME"='ICOL$')
 
Content of other_xml column
===========================
  db_version     : 10.2.0.4
  parse_schema   : SONG
  dynamic_sampling: yes
  plan_hash      : 1193947757
  Outline Data:
 
 
select * from dba_objects;



  alter system flush buffer_cache;
  alter system flush shared_pool;
drop index idx_1;

create index idx_3 on t11(object_id,object_name);


Alter session set events '10053 trace name context forever, level 1';


select * from t11 where object_name='ICOL$' and object_id=20;
Alter session set events '10053 trace name context off';

 Access Path: TableScan
    Cost:  139.65  Resp: 139.65  Degree: 0
      Cost_io: 139.00  Cost_cpu: 20044626
      Resp_io: 139.00  Resp_cpu: 20044626
  Access Path: index (AllEqRange)
    Index: IDX_2
    resc_io: 2.00  resc_cpu: 15683
    ix_sel: 1.6000e-05  ix_sel_with_filters: 1.6000e-05
    Cost: 2.00  Resp: 2.00  Degree: 1
  Access Path: index (AllEqRange)
    Index: IDX_3
    resc_io: 2.00  resc_cpu: 15683
    ix_sel: 1.6000e-05  ix_sel_with_filters: 1.6000e-05
    Cost: 2.00  Resp: 2.00  Degree: 1
  ****** trying bitmap/domain indexes ******
  ****** finished trying bitmap/domain indexes ******
  Best:: AccessPath: IndexRange  Index: IDX_2
         Cost: 2.00  Degree: 1  Resp: 2.00  Card: 5.75  Bytes: 0
***************************************
OPTIMIZER STATISTICS AND COMPUTATIONS
***************************************
GENERAL PLANS
***************************************
Considering cardinality-based initial join order.
Permutations for Starting Table :0
***********************
Join order[1]:  T11[T11]#0
***********************
Best so far: Table#: 0  cost: 2.0005  card: 5.7533  bytes: 1062
(newjo-stop-1) k:0, spcnt:0, perm:1, maxperm:80000
*********************************
Number of join permutations tried: 1
*********************************
Final - All Rows Plan:  Best join order: 1
  Cost: 2.0005  Degree: 1  Card: 6.0000  Bytes: 1062
  Resc: 2.0005  Resc_io: 2.0000  Resc_cpu: 15683
  Resp: 2.0005  Resp_io: 2.0000  Resc_cpu: 15683
kkoipt: Query block SEL$1 (#0)
******* UNPARSED QUERY IS *******
SELECT "T11"."OWNER" "OWNER","T11"."OBJECT_NAME" "OBJECT_NAME","T11"."SUBOBJECT_NAME" "SUBOBJECT_NAME","T11"."OBJECT_ID" "OBJECT_ID","T11"."DATA_OBJECT_ID" "DATA_OBJECT_ID","T11"."OBJECT_TYPE" "OBJECT_TYPE","T11"."CREATED" "CREATED","T11"."LAST_DDL_TIME" "LAST_DDL_TIME","T11"."TIMESTAMP" "TIMESTAMP","T11"."STATUS" "STATUS","T11"."TEMPORARY" "TEMPORARY","T11"."GENERATED" "GENERATED","T11"."SECONDARY" "SECONDARY" FROM "SONG"."T11" "T11" WHERE "T11"."OBJECT_ID"=20 AND "T11"."OBJECT_NAME"='ICOL$'
kkoqbc-subheap (delete addr=0x2aca370cbe38, in-use=17008, alloc=18400)
kkoqbc-end
          : call(in-use=37416, alloc=65448), compile(in-use=48936, alloc=50504)
apadrv-end: call(in-use=37416, alloc=65448), compile(in-use=49808, alloc=50504)
 
sql_id=7a6qgwc26kkq4.
Current SQL statement for this session:
select * from t11 where object_name='ICOL$' and object_id=20
 
============
Plan Table
============
-----------------------------------------------+-----------------------------------+
| Id  | Operation                    | Name    | Rows  | Bytes | Cost  | Time      |
-----------------------------------------------+-----------------------------------+
| 0   | SELECT STATEMENT             |         |       |       |     2 |           |
| 1   |  TABLE ACCESS BY INDEX ROWID | T11     |     6 |  1062 |     2 |  00:00:01 |
| 2   |   INDEX RANGE SCAN           | IDX_2   |     1 |       |     1 |  00:00:01 |
-----------------------------------------------+-----------------------------------+
Predicate Information:
----------------------
2 - access("OBJECT_NAME"='ICOL$' AND "OBJECT_ID"=20)
 
Content of other_xml column
===========================
  db_version     : 10.2.0.4
  parse_schema   : SONG
  dynamic_sampling: yes
  plan_hash      : 4084186866
  Outline Data:
 
  
  
  
  alter system flush buffer_cache;
  alter system flush shared_pool;
  
  drop index idx_3;

create index idx on t11(object_id,object_name);


Alter session set events '10053 trace name context forever, level 1';


select * from t11 where object_name='ICOL$' and object_id=20;
Alter session set events '10053 trace name context off';


Access Path: TableScan
    Cost:  139.65  Resp: 139.65  Degree: 0
      Cost_io: 139.00  Cost_cpu: 20044626
      Resp_io: 139.00  Resp_cpu: 20044626
  Access Path: index (AllEqRange)
    Index: IDX
    resc_io: 2.00  resc_cpu: 15683
    ix_sel: 1.6000e-05  ix_sel_with_filters: 1.6000e-05
    Cost: 2.00  Resp: 2.00  Degree: 1
  Access Path: index (AllEqRange)
    Index: IDX_2
    resc_io: 2.00  resc_cpu: 15683
    ix_sel: 1.6000e-05  ix_sel_with_filters: 1.6000e-05
    Cost: 2.00  Resp: 2.00  Degree: 1
  ****** trying bitmap/domain indexes ******
  ****** finished trying bitmap/domain indexes ******
  Best:: AccessPath: IndexRange  Index: IDX
         Cost: 2.00  Degree: 1  Resp: 2.00  Card: 5.75  Bytes: 0
***************************************
OPTIMIZER STATISTICS AND COMPUTATIONS
***************************************
GENERAL PLANS
***************************************
Considering cardinality-based initial join order.
Permutations for Starting Table :0
***********************
Join order[1]:  T11[T11]#0
***********************
Best so far: Table#: 0  cost: 2.0005  card: 5.7533  bytes: 1062
(newjo-stop-1) k:0, spcnt:0, perm:1, maxperm:80000
*********************************
Number of join permutations tried: 1
*********************************
Final - All Rows Plan:  Best join order: 1
  Cost: 2.0005  Degree: 1  Card: 6.0000  Bytes: 1062
  Resc: 2.0005  Resc_io: 2.0000  Resc_cpu: 15683
  Resp: 2.0005  Resp_io: 2.0000  Resc_cpu: 15683
kkoipt: Query block SEL$1 (#0)
******* UNPARSED QUERY IS *******
SELECT "T11"."OWNER" "OWNER","T11"."OBJECT_NAME" "OBJECT_NAME","T11"."SUBOBJECT_NAME" "SUBOBJECT_NAME","T11"."OBJECT_ID" "OBJECT_ID","T11"."DATA_OBJECT_ID" "DATA_OBJECT_ID","T11"."OBJECT_TYPE" "OBJECT_TYPE","T11"."CREATED" "CREATED","T11"."LAST_DDL_TIME" "LAST_DDL_TIME","T11"."TIMESTAMP" "TIMESTAMP","T11"."STATUS" "STATUS","T11"."TEMPORARY" "TEMPORARY","T11"."GENERATED" "GENERATED","T11"."SECONDARY" "SECONDARY" FROM "SONG"."T11" "T11" WHERE "T11"."OBJECT_NAME"='ICOL$' AND "T11"."OBJECT_ID"=20
kkoqbc-subheap (delete addr=0x2b431ecbbe38, in-use=17008, alloc=18400)
kkoqbc-end
          : call(in-use=37416, alloc=65448), compile(in-use=48936, alloc=50504)
apadrv-end: call(in-use=37416, alloc=65448), compile(in-use=49808, alloc=50504)
 
sql_id=7a6qgwc26kkq4.
Current SQL statement for this session:
select * from t11 where object_name='ICOL$' and object_id=20
 
============
Plan Table
============
-----------------------------------------------+-----------------------------------+
| Id  | Operation                    | Name    | Rows  | Bytes | Cost  | Time      |
-----------------------------------------------+-----------------------------------+
| 0   | SELECT STATEMENT             |         |       |       |     2 |           |
| 1   |  TABLE ACCESS BY INDEX ROWID | T11     |     6 |  1062 |     2 |  00:00:01 |
| 2   |   INDEX RANGE SCAN           | IDX     |     1 |       |     1 |  00:00:01 |
-----------------------------------------------+-----------------------------------+
Predicate Information:
----------------------
2 - access("OBJECT_ID"=20 AND "OBJECT_NAME"='ICOL$')
 
Content of other_xml column
===========================
  db_version     : 10.2.0.4
  parse_schema   : SONG
  dynamic_sampling: yes
  plan_hash      : 1540313942
  Outline Data:
 
  SINGLE TABLE ACCESS PATH
  -----------------------------------------
  BEGIN Single Table Cardinality Estimation
  -----------------------------------------
*** 2014-05-21 23:57:46.850
** Performing dynamic sampling initial checks. **
** Not using dynamic sampling since sampling disabled or level equals 0.
  Column (#2): OBJECT_NAME(VARCHAR2)  NO STATISTICS (using defaults)
    AvgLen: 66.00 NDV: 1812 Nulls: 0 Density: 5.5179e-04
  Column (#4): OBJECT_ID(NUMBER)  NO STATISTICS (using defaults)
    AvgLen: 13.00 NDV: 1812 Nulls: 0 Density: 5.5179e-04
  Table: T11  Alias: T11     
    Card: Original: 57993  Rounded: 6  Computed: 5.80  Non Adjusted: 5.80
  -----------------------------------------
  END   Single Table Cardinality Estimation
  -----------------------------------------
  Access Path: TableScan
    Cost:  139.66  Resp: 139.66  Degree: 0
      Cost_io: 139.00  Cost_cpu: 20164479
      Resp_io: 139.00  Resp_cpu: 20164479
  Access Path: index (AllEqRange)
    Index: IDX
    resc_io: 2.00  resc_cpu: 15683
    ix_sel: 1.9926e-05  ix_sel_with_filters: 1.9926e-05
    Cost: 2.00  Resp: 2.00  Degree: 1
  Access Path: index (AllEqRange)
    Index: IDX_2
    resc_io: 2.00  resc_cpu: 15683
    ix_sel: 1.9926e-05  ix_sel_with_filters: 1.9926e-05
    Cost: 2.00  Resp: 2.00  Degree: 1
  ****** trying bitmap/domain indexes ******
  ****** finished trying bitmap/domain indexes ******
  Best:: AccessPath: IndexRange  Index: IDX
         Cost: 2.00  Degree: 1  Resp: 2.00  Card: 5.80  Bytes: 0
***************************************
OPTIMIZER STATISTICS AND COMPUTATIONS
***************************************
GENERAL PLANS
***************************************
Considering cardinality-based initial join order.
Permutations for Starting Table :0
***********************
Join order[1]:  T11[T11]#0
***********************
Best so far: Table#: 0  cost: 2.0005  card: 5.7993  bytes: 1062
(newjo-stop-1) k:0, spcnt:0, perm:1, maxperm:80000
*********************************
Number of join permutations tried: 1
*********************************
Final - All Rows Plan:  Best join order: 1
  Cost: 2.0005  Degree: 1  Card: 6.0000  Bytes: 1062
  Resc: 2.0005  Resc_io: 2.0000  Resc_cpu: 15683
  Resp: 2.0005  Resp_io: 2.0000  Resc_cpu: 15683
kkoipt: Query block SEL$1 (#0)
******* UNPARSED QUERY IS *******
SELECT /*+ */ "T11"."OWNER" "OWNER","T11"."OBJECT_NAME" "OBJECT_NAME","T11"."SUBOBJECT_NAME" "SUBOBJECT_NAME","T11"."OBJECT_ID" "OBJECT_ID","T11"."DATA_OBJECT_ID" "DATA_OBJECT_ID","T11"."OBJECT_TYPE" "OBJECT_TYPE","T11"."CREATED" "CREATED","T11"."LAST_DDL_TIME" "LAST_DDL_TIME","T11"."TIMESTAMP" "TIMESTAMP","T11"."STATUS" "STATUS","T11"."TEMPORARY" "TEMPORARY","T11"."GENERATED" "GENERATED","T11"."SECONDARY" "SECONDARY" FROM "SONG"."T11" "T11" WHERE "T11"."OBJECT_NAME"='ICOL$' AND "T11"."OBJECT_ID"=20
kkoqbc-subheap (delete addr=0x2b1185b7be38, in-use=16056, alloc=18400)
kkoqbc-end
          : call(in-use=29840, alloc=65448), compile(in-use=48624, alloc=50504)
apadrv-end: call(in-use=29840, alloc=65448), compile(in-use=49408, alloc=50504)
 
sql_id=22bwf2zav4aha.
Current SQL statement for this session:
select /*+ dynamic_sampling(t11 0)*/ * from t11 where object_name='ICOL$' and object_id=20
 
============
Plan Table
============
-----------------------------------------------+-----------------------------------+
| Id  | Operation                    | Name    | Rows  | Bytes | Cost  | Time      |
-----------------------------------------------+-----------------------------------+
| 0   | SELECT STATEMENT             |         |       |       |     2 |           |
| 1   |  TABLE ACCESS BY INDEX ROWID | T11     |     6 |  1062 |     2 |  00:00:01 |
| 2   |   INDEX RANGE SCAN           | IDX     |     1 |       |     1 |  00:00:01 |
-----------------------------------------------+-----------------------------------+
Predicate Information:
----------------------
2 - access("OBJECT_ID"=20 AND "OBJECT_NAME"='ICOL$')
 
Content of other_xml column
===========================
  db_version     : 10.2.0.4
  parse_schema   : SONG
  plan_hash      : 1540313942
  Outline Data:
  /*+
    BEGIN_OUTLINE_DATA
      IGNORE_OPTIM_EMBEDDED_HINTS
      OPTIMIZER_FEATURES_ENABLE('10.2.0.4')
      ALL_ROWS
      OUTLINE_LEAF(@"SEL$1")
      INDEX_RS_ASC(@"SEL$1" "T11"@"SEL$1" ("T11"."OBJECT_ID" "T11"."OBJECT_NAME"))
    END_OUTLINE_DATA
  */
 
 
 drop index idx;
 create index idx_3 on t11(object_id,object_name);
 
 ****************
QUERY BLOCK TEXT
****************
select /*+ dynamic_sampling(t11 0)*/ * from t11 where object_name='ICOL$' and object_id=20
*********************
QUERY BLOCK SIGNATURE
*********************
qb name was generated
signature (optimizer): qb_name=SEL$1 nbfros=1 flg=0
  fro(0): flg=0 objn=57349 hint_alias="T11"@"SEL$1"
*****************************
SYSTEM STATISTICS INFORMATION
*****************************
  Using NOWORKLOAD Stats
  CPUSPEED: 2563 millions instruction/sec
  IOTFRSPEED: 4096 bytes per millisecond (default is 4096)
  IOSEEKTIM: 10 milliseconds (default is 10)
***************************************
BASE STATISTICAL INFORMATION
***********************
Table Stats::
  Table: T11  Alias: T11  (NOT ANALYZED)
    #Rows: 57993  #Blks:  710  AvgRowLen:  100.00
Index Stats::
  Index: IDX_2  Col#: 2 4
    LVLS: 1  #LB: 281  #DK: 50186  LB/K: 1.00  DB/K: 1.00  CLUF: 25485.00
  Index: IDX_3  Col#: 4 2
    LVLS: 1  #LB: 281  #DK: 50186  LB/K: 1.00  DB/K: 1.00  CLUF: 749.00
***************************************
SINGLE TABLE ACCESS PATH
  -----------------------------------------
  BEGIN Single Table Cardinality Estimation
  -----------------------------------------
*** 2014-05-22 00:00:45.072
** Performing dynamic sampling initial checks. **
** Not using dynamic sampling since sampling disabled or level equals 0.
  Column (#2): OBJECT_NAME(VARCHAR2)  NO STATISTICS (using defaults)
    AvgLen: 66.00 NDV: 1812 Nulls: 0 Density: 5.5179e-04
  Column (#4): OBJECT_ID(NUMBER)  NO STATISTICS (using defaults)
    AvgLen: 13.00 NDV: 1812 Nulls: 0 Density: 5.5179e-04
  Table: T11  Alias: T11     
    Card: Original: 57993  Rounded: 6  Computed: 5.80  Non Adjusted: 5.80
  -----------------------------------------
  END   Single Table Cardinality Estimation
  -----------------------------------------
  Access Path: TableScan
    Cost:  139.66  Resp: 139.66  Degree: 0
      Cost_io: 139.00  Cost_cpu: 20164479
      Resp_io: 139.00  Resp_cpu: 20164479
  Access Path: index (AllEqRange)
    Index: IDX_2
    resc_io: 2.00  resc_cpu: 15683
    ix_sel: 1.9926e-05  ix_sel_with_filters: 1.9926e-05
    Cost: 2.00  Resp: 2.00  Degree: 1
  Access Path: index (AllEqRange)
    Index: IDX_3
    resc_io: 2.00  resc_cpu: 15683
    ix_sel: 1.9926e-05  ix_sel_with_filters: 1.9926e-05
    Cost: 2.00  Resp: 2.00  Degree: 1
  ****** trying bitmap/domain indexes ******
  ****** finished trying bitmap/domain indexes ******
  Best:: AccessPath: IndexRange  Index: IDX_2
         Cost: 2.00  Degree: 1  Resp: 2.00  Card: 5.80  Bytes: 0
***************************************
OPTIMIZER STATISTICS AND COMPUTATIONS
***************************************
GENERAL PLANS
***************************************
Considering cardinality-based initial join order.
Permutations for Starting Table :0
***********************
Join order[1]:  T11[T11]#0
***********************
Best so far: Table#: 0  cost: 2.0005  card: 5.7993  bytes: 1062
(newjo-stop-1) k:0, spcnt:0, perm:1, maxperm:80000
*********************************
Number of join permutations tried: 1
*********************************
Final - All Rows Plan:  Best join order: 1
  Cost: 2.0005  Degree: 1  Card: 6.0000  Bytes: 1062
  Resc: 2.0005  Resc_io: 2.0000  Resc_cpu: 15683
  Resp: 2.0005  Resp_io: 2.0000  Resc_cpu: 15683
kkoipt: Query block SEL$1 (#0)
******* UNPARSED QUERY IS *******
SELECT /*+ */ "T11"."OWNER" "OWNER","T11"."OBJECT_NAME" "OBJECT_NAME","T11"."SUBOBJECT_NAME" "SUBOBJECT_NAME","T11"."OBJECT_ID" "OBJECT_ID","T11"."DATA_OBJECT_ID" "DATA_OBJECT_ID","T11"."OBJECT_TYPE" "OBJECT_TYPE","T11"."CREATED" "CREATED","T11"."LAST_DDL_TIME" "LAST_DDL_TIME","T11"."TIMESTAMP" "TIMESTAMP","T11"."STATUS" "STATUS","T11"."TEMPORARY" "TEMPORARY","T11"."GENERATED" "GENERATED","T11"."SECONDARY" "SECONDARY" FROM "SONG"."T11" "T11" WHERE "T11"."OBJECT_ID"=20 AND "T11"."OBJECT_NAME"='ICOL$'
kkoqbc-subheap (delete addr=0x2b479b4abe38, in-use=16056, alloc=18400)
kkoqbc-end
          : call(in-use=29840, alloc=65448), compile(in-use=48624, alloc=50504)
apadrv-end: call(in-use=29840, alloc=65448), compile(in-use=49408, alloc=50504)
 
sql_id=22bwf2zav4aha.
Current SQL statement for this session:
select /*+ dynamic_sampling(t11 0)*/ * from t11 where object_name='ICOL$' and object_id=20
 
============
Plan Table
============
-----------------------------------------------+-----------------------------------+
| Id  | Operation                    | Name    | Rows  | Bytes | Cost  | Time      |
-----------------------------------------------+-----------------------------------+
| 0   | SELECT STATEMENT             |         |       |       |     2 |           |
| 1   |  TABLE ACCESS BY INDEX ROWID | T11     |     6 |  1062 |     2 |  00:00:01 |
| 2   |   INDEX RANGE SCAN           | IDX_2   |     1 |       |     1 |  00:00:01 |
-----------------------------------------------+-----------------------------------+
Predicate Information:
----------------------
2 - access("OBJECT_NAME"='ICOL$' AND "OBJECT_ID"=20)
 
Content of other_xml column
===========================
  db_version     : 10.2.0.4
  parse_schema   : SONG
  plan_hash      : 4084186866
  Outline Data:
  /*+
    BEGIN_OUTLINE_DATA
      IGNORE_OPTIM_EMBEDDED_HINTS
      OPTIMIZER_FEATURES_ENABLE('10.2.0.4')
      ALL_ROWS
      OUTLINE_LEAF(@"SEL$1")
      INDEX_RS_ASC(@"SEL$1" "T11"@"SEL$1" ("T11"."OBJECT_NAME" "T11"."OBJECT_ID"))
    END_OUTLINE_DATA
  */
 

來自 “ ITPUB部落格 ” ，連結：http://blog.itpub.net/25099483/viewspace-1166852/，如需轉載，請註明出處，否則將追究法律責任。

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