Oracle技术之和分区表相关的一点总结（四）

3.访问全部数据,我们发现访问heap表要比访问分区表是少了一些逻辑读：

88429<88573,其实这点差别对性能来说是无关紧要的，重要的是说明了一个问题，

那就是尽量让执行的sql少读、少些，这也是sql调整的最终目的，相差的这100

多逻辑读主要发生在查找metadata上...

SQL> select * from t1 ;

已选择1260672行。

已用时间: 00: 00: 26.70

执行计划

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

Plan hash value: 3617692013

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

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |

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

| 0 | SELECT STATEMENT | | 1482K| 111M| 1064 (3)| 00:00:13 |

| 1 | TABLE ACCESS FULL| T1 | 1482K| 111M| 1064 (3)| 00:00:13 |

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

Note

-----

- dynamic sampling used for this statement

统计信息

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

5 recursive calls

0 db block gets

88511 consistent gets

0 physical reads

0 redo size

44940044 bytes sent via SQL*Net to client

924869 bytes received via SQL*Net from client

84046 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

1260672 rows processed

SQL> select * from t1 ;

已选择1260672行。

已用时间: 00: 00: 24.59

执行计划

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

Plan hash value: 3617692013

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

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |

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

| 0 | SELECT STATEMENT | | 1482K| 111M| 1064 (3)| 00:00:13 |

| 1 | TABLE ACCESS FULL| T1 | 1482K| 111M| 1064 (3)| 00:00:13 |

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

Note

-----

- dynamic sampling used for this statement

统计信息

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

0 recursive calls

0 db block gets

88429 consistent gets

0 physical reads

0 redo size

44940044 bytes sent via SQL*Net to client

924869 bytes received via SQL*Net from client

84046 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

1260672 rows processed

SQL> select * from t ;

已选择1260544行。

已用时间: 00: 00: 25.71

执行计划

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

Plan hash value: 3557914527

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

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

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pst

art| Pstop |

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

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

| 0 | SELECT STATEMENT | | 1317K| 37M| 1094 (3)| 00:00:14 |

| |

| 1 | PARTITION RANGE ALL| | 1317K| 37M| 1094 (3)| 00:00:14 |

1 | 5 |

| 2 | TABLE ACCESS FULL | T | 1317K| 37M| 1094 (3)| 00:00:14 |

1 | 5 |

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

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

Note

-----

- dynamic sampling used for this statement

统计信息

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

7 recursive calls

2 db block gets

90275 consistent gets

2133 physical reads

114820 redo size

39895221 bytes sent via SQL*Net to client

924781 bytes received via SQL*Net from client

84038 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

1260544 rows processed

SQL> select * from t ;

已选择1260544行。

已用时间: 00: 00: 24.90

执行计划

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

Plan hash value: 3557914527

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

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

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pst

art| Pstop |

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

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

| 0 | SELECT STATEMENT | | 1317K| 37M| 1094 (3)| 00:00:14 |

| |

| 1 | PARTITION RANGE ALL| | 1317K| 37M| 1094 (3)| 00:00:14 |

1 | 5 |

| 2 | TABLE ACCESS FULL | T | 1317K| 37M| 1094 (3)| 00:00:14 |

1 | 5 |

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

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

Note

-----

- dynamic sampling used for this statement

统计信息

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

0 recursive calls

0 db block gets

88573 consistent gets

0 physical reads

0 redo size

39895221 bytes sent via SQL*Net to client

924781 bytes received via SQL*Net from client

84038 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

1260544 rows processed

SQL>

--==========================

有index的情况,创建global index：

有index其实也是一样的，首先通过index找到rowid，之后最终通过rowid

再去访问表，如果访问的数据尽可能的可以集中在一些分区内，那么访问

分区表的性能肯定要优于heap表

SQL> create index idx_t on t(object_id) tablespace users;

索引已创建。

已用时间: 00: 00: 10.21

SQL> create index idx_t1 on t1(object_id) tablespace users;

索引已创建。

已用时间: 00: 00: 06.89

SQL>

SQL> exec dbms_stats.gather_table_stats('SYS','T',CASCADE=>TRUE);

PL/SQL 过程已成功完成。

已用时间: 00: 00: 06.00

SQL> exec dbms_stats.gather_table_stats('SYS','T1',CASCADE=>TRUE);

PL/SQL 过程已成功完成。

已用时间: 00: 00: 03.21

SQL>

--有global index跨分区访问

SQL> select /*+ index(t idx_t) */ * from t where object_id<3000;

已选择377984行。

已用时间: 00: 00: 07.75

执行计划

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

Plan hash value: 3317799281

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

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

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)

| Time | Pstart| Pstop |

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

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

| 0 | SELECT STATEMENT | | 368K| 7922K| 363K (1)

| 01:12:41 | | |

| 1 | TABLE ACCESS BY GLOBAL INDEX ROWID| T | 368K| 7922K| 363K (1)

| 01:12:41 | ROWID | ROWID |

|* 2 | INDEX RANGE SCAN | IDX_T | 368K| | 986 (1)

| 00:00:12 | | |

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

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

Predicate Information (identified by operation id):

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

2 - access("OBJECT_ID"<3000)

统计信息

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

1 recursive calls

0 db block gets

398707 consistent gets

0 physical reads

0 redo size

12757072 bytes sent via SQL*Net to client

277563 bytes received via SQL*Net from client

25200 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

377984 rows processed

SQL> select /*+ index(t idx_t) */ * from t where object_id<3000;

已选择377984行。

已用时间: 00: 00: 09.43

执行计划

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

Plan hash value: 3317799281

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

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

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)

| Time | Pstart| Pstop |

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

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

| 0 | SELECT STATEMENT | | 368K| 7922K| 363K (1)

| 01:12:41 | | |

| 1 | TABLE ACCESS BY GLOBAL INDEX ROWID| T | 368K| 7922K| 363K (1)

| 01:12:41 | ROWID | ROWID |

|* 2 | INDEX RANGE SCAN | IDX_T | 368K| | 986 (1)

| 00:00:12 | | |

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

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

Predicate Information (identified by operation id):

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

2 - access("OBJECT_ID"<3000)

统计信息

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

0 recursive calls

0 db block gets

398707 consistent gets

0 physical reads

0 redo size

12757072 bytes sent via SQL*Net to client

277563 bytes received via SQL*Net from client

25200 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

377984 rows processed

SQL>

--======================

--有global index不垮分区访问：

SQL> select /*+ index(t1 idx_t1) */ * from t1 where object_id<2000;

已选择249984行。

已用时间: 00: 00: 05.57

执行计划

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

Plan hash value: 50753647

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

------

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time

|

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

------

| 0 | SELECT STATEMENT | | 245K| 5264K| 245K (1)| 00:4

9:12 |

| 1 | TABLE ACCESS BY INDEX ROWID| T1 | 245K| 5264K| 245K (1)| 00:4

9:12 |

|* 2 | INDEX RANGE SCAN | IDX_T1 | 245K| | 522 (2)| 00:0

0:07 |

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

------

Predicate Information (identified by operation id):

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

2 - access("OBJECT_ID"<2000)

统计信息

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

1 recursive calls

0 db block gets

266985 consistent gets

0 physical reads

0 redo size

8439590 bytes sent via SQL*Net to client

183700 bytes received via SQL*Net from client

16667 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

249984 rows processed

SQL> select /*+ index(t1 idx_t1) */ * from t1 where object_id<2000;

已选择249984行。

已用时间: 00: 00: 05.42

执行计划

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

Plan hash value: 50753647

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

------

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time

|

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

------

| 0 | SELECT STATEMENT | | 245K| 5264K| 245K (1)| 00:4

9:12 |

| 1 | TABLE ACCESS BY INDEX ROWID| T1 | 245K| 5264K| 245K (1)| 00:4

9:12 |

|* 2 | INDEX RANGE SCAN | IDX_T1 | 245K| | 522 (2)| 00:0

0:07 |

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

------

Predicate Information (identified by operation id):

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

2 - access("OBJECT_ID"<2000)

统计信息

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

0 recursive calls

0 db block gets

266985 consistent gets

0 physical reads

0 redo size

8439590 bytes sent via SQL*Net to client

183700 bytes received via SQL*Net from client

16667 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

249984 rows processed

SQL> select /*+ index(t idx_t) */ * from t where object_id<2000;

已选择249984行。

已用时间: 00: 00: 04.93

执行计划

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

Plan hash value: 2063514567

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

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

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)

| Time | Pstart| Pstop |

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

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

| 0 | SELECT STATEMENT | | 259K| 5073K| 1241K (1)

| 04:08:20 | | |

| 1 | TABLE ACCESS BY GLOBAL INDEX ROWID| T | 259K| 5073K| 1241K (1)

| 04:08:20 | 1 | 1 |

|* 2 | INDEX RANGE SCAN | IDX_T | 1260K| | 3366 (1)

| 00:00:41 | | |

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

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

Predicate Information (identified by operation id):

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

2 - access("OBJECT_ID"<2000)

统计信息

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

44 recursive calls

0 db block gets

262733 consistent gets

0 physical reads

0 redo size

8439590 bytes sent via SQL*Net to client

183700 bytes received via SQL*Net from client

16667 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

249984 rows processed

SQL>

SQL> select /*+ index(t idx_t) */ * from t where object_id<2000;

已选择249984行。

已用时间: 00: 00: 04.62

执行计划

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

Plan hash value: 2063514567

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

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

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)

| Time | Pstart| Pstop |

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

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

| 0 | SELECT STATEMENT | | 259K| 5073K| 1241K (1)

| 04:08:20 | | |

| 1 | TABLE ACCESS BY GLOBAL INDEX ROWID| T | 259K| 5073K| 1241K (1)

| 04:08:20 | 1 | 1 |

|* 2 | INDEX RANGE SCAN | IDX_T | 1260K| | 3366 (1)

| 00:00:41 | | |

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

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

Predicate Information (identified by operation id):

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

2 - access("OBJECT_ID"<2000)

统计信息

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

0 recursive calls

0 db block gets

262727 consistent gets

0 physical reads

0 redo size

8439590 bytes sent via SQL*Net to client

183700 bytes received via SQL*Net from client

16667 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

249984 rows processed

SQL>

--======================

SQL> exec dbms_stats.gather_table_stats('SYS','T',CASCADE=>TRUE);

PL/SQL 过程已成功完成。

已用时间: 00: 00: 05.82

SQL> exec dbms_stats.gather_table_stats('SYS','T1',CASCADE=>TRUE);

PL/SQL 过程已成功完成。

已用时间: 00: 00: 03.17

SQL>

--local index:

SQL> select /*+ index(t1 idx_t1) */ * from t1 where object_id<3000;

已选择377984行。

已用时间: 00: 00: 09.46

执行计划

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

Plan hash value: 50753647

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

------

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time

|

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

------

| 0 | SELECT STATEMENT | | 370K| 7963K| 371K (1)| 01:1

4:16 |

| 1 | TABLE ACCESS BY INDEX ROWID| T1 | 370K| 7963K| 371K (1)| 01:1

4:16 |

|* 2 | INDEX RANGE SCAN | IDX_T1 | 370K| | 786 (2)| 00:0

0:10 |

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

------

Predicate Information (identified by operation id):

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

2 - access("OBJECT_ID"<3000)

统计信息

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

150 recursive calls

0 db block gets

403726 consistent gets

0 physical reads

0 redo size

12757072 bytes sent via SQL*Net to client

277563 bytes received via SQL*Net from client

25200 SQL*Net roundtrips to/from client

3 sorts (memory)

0 sorts (disk)

377984 rows processed

SQL> select /*+ index(t1 idx_t1) */ * from t1 where object_id<3000;

已选择377984行。

已用时间: 00: 00: 08.28

执行计划

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

Plan hash value: 50753647

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

------

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time

|

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

------

| 0 | SELECT STATEMENT | | 370K| 7963K| 371K (1)| 01:1

4:16 |

| 1 | TABLE ACCESS BY INDEX ROWID| T1 | 370K| 7963K| 371K (1)| 01:1

4:16 |

|* 2 | INDEX RANGE SCAN | IDX_T1 | 370K| | 786 (2)| 00:0

0:10 |

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

------

Predicate Information (identified by operation id):

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

2 - access("OBJECT_ID"<3000)

统计信息

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

0 recursive calls

0 db block gets

403706 consistent gets

0 physical reads

0 redo size

12757072 bytes sent via SQL*Net to client

277563 bytes received via SQL*Net from client

25200 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

377984 rows processed

SQL> select /*+ index(t idx_t) */ * from t where object_id<3000;

已选择377984行。

已用时间: 00: 00: 07.17

执行计划

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

Plan hash value: 3038871768

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

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

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)

| Time | Pstart| Pstop |

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

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

| 0 | SELECT STATEMENT | | 368K| 7566K| 363K (1)

| 01:12:40 | | |

| 1 | PARTITION RANGE ITERATOR | | 368K| 7566K| 363K (1)

| 01:12:40 | 1 | 2 |

| 2 | TABLE ACCESS BY LOCAL INDEX ROWID| T | 368K| 7566K| 363K (1)

| 01:12:40 | 1 | 2 |

|* 3 | INDEX RANGE SCAN | IDX_T | 368K| | 783 (2)

| 00:00:10 | 1 | 2 |

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

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

Predicate Information (identified by operation id):

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

3 - access("OBJECT_ID"<3000)

统计信息

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

195 recursive calls

0 db block gets

398680 consistent gets

0 physical reads

0 redo size

5145251 bytes sent via SQL*Net to client

277563 bytes received via SQL*Net from client

25200 SQL*Net roundtrips to/from client

6 sorts (memory)

0 sorts (disk)

377984 rows processed

SQL> select /*+ index(t idx_t) */ * from t where object_id<3000;

已选择377984行。

已用时间: 00: 00: 07.42

执行计划

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

Plan hash value: 3038871768

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

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

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)

| Time | Pstart| Pstop |

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

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

| 0 | SELECT STATEMENT | | 368K| 7566K| 363K (1)

| 01:12:40 | | |

| 1 | PARTITION RANGE ITERATOR | | 368K| 7566K| 363K (1)

| 01:12:40 | 1 | 2 |

| 2 | TABLE ACCESS BY LOCAL INDEX ROWID| T | 368K| 7566K| 363K (1)

| 01:12:40 | 1 | 2 |

|* 3 | INDEX RANGE SCAN | IDX_T | 368K| | 783 (2)

| 00:00:10 | 1 | 2 |

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

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

Predicate Information (identified by operation id):

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

3 - access("OBJECT_ID"<3000)

统计信息

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

0 recursive calls

0 db block gets

398633 consistent gets

0 physical reads

0 redo size

5145251 bytes sent via SQL*Net to client

277563 bytes received via SQL*Net from client

25200 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

377984 rows processed

SQL>

--===============================

有local index不垮分区访问：

SQL> select /*+ index(t idx_t) */ * from t where object_id<2000;

已选择249984行。

已用时间: 00: 00: 04.93

执行计划

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

Plan hash value: 3965956311

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

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

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)

| Time | Pstart| Pstop |

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

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

| 0 | SELECT STATEMENT | | 254K| 4962K| 245K (1)

| 00:49:11 | | |

| 1 | PARTITION RANGE SINGLE | | 254K| 4962K| 245K (1)

| 00:49:11 | 1 | 1 |

| 2 | TABLE ACCESS BY LOCAL INDEX ROWID| T | 254K| 4962K| 245K (1)

| 00:49:11 | 1 | 1 |

|* 3 | INDEX RANGE SCAN | IDX_T | 249K| | 528 (2)

| 00:00:07 | 1 | 1 |

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

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

Predicate Information (identified by operation id):

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

3 - access("OBJECT_ID"<2000)

统计信息

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

24 recursive calls

0 db block gets

262679 consistent gets

0 physical reads

0 redo size

3406055 bytes sent via SQL*Net to client

183700 bytes received via SQL*Net from client

16667 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

249984 rows processed

SQL> select /*+ index(t idx_t) */ * from t where object_id<2000;

已选择249984行。

已用时间: 00: 00: 03.48

执行计划

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

Plan hash value: 3965956311

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

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

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)

| Time | Pstart| Pstop |

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

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

| 0 | SELECT STATEMENT | | 254K| 4962K| 245K (1)

| 00:49:11 | | |

| 1 | PARTITION RANGE SINGLE | | 254K| 4962K| 245K (1)

| 00:49:11 | 1 | 1 |

| 2 | TABLE ACCESS BY LOCAL INDEX ROWID| T | 254K| 4962K| 245K (1)

| 00:49:11 | 1 | 1 |

|* 3 | INDEX RANGE SCAN | IDX_T | 249K| | 528 (2)

| 00:00:07 | 1 | 1 |

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

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

Predicate Information (identified by operation id):

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

3 - access("OBJECT_ID"<2000)

统计信息

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

0 recursive calls

0 db block gets

262676 consistent gets

0 physical reads

0 redo size

3406055 bytes sent via SQL*Net to client

183700 bytes received via SQL*Net from client

16667 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

249984 rows processed

SQL> select /*+ index(t1 idx_t1) */ * from t1 where object_id<2000;

已选择249984行。

已用时间: 00: 00: 05.40

执行计划

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

Plan hash value: 50753647

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

------

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time

|

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

------

| 0 | SELECT STATEMENT | | 247K| 5306K| 247K (1)| 00:4

9:29 |

| 1 | TABLE ACCESS BY INDEX ROWID| T1 | 247K| 5306K| 247K (1)| 00:4

9:29 |

|* 2 | INDEX RANGE SCAN | IDX_T1 | 247K| | 525 (2)| 00:0

0:07 |

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

------

Predicate Information (identified by operation id):

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

2 - access("OBJECT_ID"<2000)

统计信息

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

0 recursive calls

0 db block gets

266985 consistent gets

0 physical reads

0 redo size

8439590 bytes sent via SQL*Net to client

183700 bytes received via SQL*Net from client

16667 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

249984 rows processed

SQL> select /*+ index(t1 idx_t1) */ * from t1 where object_id<2000;

已选择249984行。

已用时间: 00: 00: 05.70

执行计划

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

Plan hash value: 50753647

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

------

| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time

|

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

------

| 0 | SELECT STATEMENT | | 247K| 5306K| 247K (1)| 00:4

9:29 |

| 1 | TABLE ACCESS BY INDEX ROWID| T1 | 247K| 5306K| 247K (1)| 00:4

9:29 |

|* 2 | INDEX RANGE SCAN | IDX_T1 | 247K| | 525 (2)| 00:0

0:07 |

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

------

Predicate Information (identified by operation id):

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

2 - access("OBJECT_ID"<2000)

统计信息

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

0 recursive calls

0 db block gets

266985 consistent gets

0 physical reads

0 redo size

8439590 bytes sent via SQL*Net to client

183700 bytes received via SQL*Net from client

16667 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

249984 rows processed

SQL>

--=========================

SQL> create index idx_t_name on t(object_name) tablespace users;

索引已创建。

SQL>

--=========================

SQL> select index_name,status from dba_indexes where index_name='IDX_T_NAME';

INDEX_NAME STATUS

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

IDX_T_NAME VALID

SQL> alter table t truncate partition p4;

表被截断。

--在分区表上创建的global index(注意非分区)，即使我们truncate partition

其实这个global index是不会自动维护的。

SQL> select index_name,status from dba_indexes where index_name='IDX_T_NAME';

INDEX_NAME STATUS

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

IDX_T_NAME UNUSABLE

SQL> COL OBJECT_NAME FORMAT A20

SQL> select object_name,status from dba_objects where object_name='IDX_T_NAME';

OBJECT_NAME STATUS

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

IDX_T_NAME VALID

SQL>

SQL> select bytes/1024/1024 m from dba_segments where segment_name='IDX_T_NAME';

M

----------

47

SQL> alter index idx_t_name rebuild;

索引已更改。

SQL> select bytes/1024/1024 m from dba_segments where segment_name='IDX_T_NAME';

M

----------

37

SQL> select index_name,status from dba_indexes where index_name='IDX_T_NAME';

INDEX_NAME STATUS

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

IDX_T_NAME VALID

SQL>

--==========================

验证一下dml对global index的影响,dml操作oracle会自动update global index(注意:并非global partition index)，这个

比较好理解，也应该这样做...

SQL> select name,del_lf_rows,del_lf_rows_len from index_stats;

NAME DEL_LF_ROWS DEL_LF_ROWS_LEN

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

IDX_T_NAME 256 10112

SQL>

SQL> delete from t where object_id=5002;

已删除128行。

SQL> commit;

提交完成。

SQL> analyze index idx_t_name validate structure;

索引已分析

SQL> select name,del_lf_rows,del_lf_rows_len from index_stats;

NAME DEL_LF_ROWS DEL_LF_ROWS_LEN

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

IDX_T_NAME 384 15616

SQL>

SQL> select index_name,status from dba_indexes where index_name='IDX_T_NAME';

INDEX_NAME STATUS

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

IDX_T_NAME VALID

--=========================

验证在分区表上创建主键和唯一索引的情况：

SQL> truncate table t ;

表被截断。

SQL> alter table t add pk number;

表已更改。

SQL> insert into t(pk,object_id,object_name) select rownum,object_id,object_name

from t1;

已创建1260672行。

SQL> commit;

提交完成。

SQL> alter table t add constraint pk_t primary key (pk);

表已更改。

SQL> alter table t drop constraint pk_t;

表已更改。

SQL> create unique index idx_t_pk on t(pk) tablespace users;

索引已创建。

SQL> create unique index idx_t_pk on t(pk) local tablespace users;

create unique index idx_t_pk on t(pk) local tablespace users

*

第 1 行出现错误:

ORA-14039: 分区列必须构成 UNIQUE 索引的关键字列子集

SQL> create unique index idx_t_pk on t(pk,object_id) local tablespace users;

索引已创建。

SQL> drop index idx_t_pk;

索引已删除。

SQL> alter table t add constraint pk_t primary key (pk) using index local;

alter table t add constraint pk_t primary key (pk) using index local

*

第 1 行出现错误:

ORA-14039: 分区列必须构成 UNIQUE 索引的关键字列子集

SQL> alter table t add constraint pk_t primary key (pk,object_id) using index l

ocal;

表已更改。

SQL> alter table t drop constraint pk_t;

表已更改。

SQL> create index idx_t_pk on t(pk) local tablespace users;

索引已创建。

SQL> drop index idx_t_pk;

索引已删除。

SQL>

结论:不管我们在创建unique index还是添加primary key时，只要我们

想把index创建成local分区index，那么就应该至少包含分区列...而不是象

网上有些人说的在分区表上创建primary key或者nuique index时必须包含分区列。

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