普通索引的使用方式

环境准备：

SCOTT@test>select * from v$version;

BANNER

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

Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - Production

PL/SQL Release 11.2.0.4.0 - Production

CORE 11.2.0.4.0 Production

TNS for Linux: Version 11.2.0.4.0 - Production

NLSRTL Version 11.2.0.4.0 - Production

SCOTT@test>create table ob as select * from dba_objects;

Table created.

Elapsed: 00:00:01.10

SCOTT@test>set autot trace;

SCOTT@test>analyze table ob compute statistics;

Table analyzed.

Elapsed: 00:00:01.89

SCOTT@test>set lines 150

1. INDEX RANGE SCAN

SCOTT@test>create index i_ob_id on ob(object_id);

Index created.

Elapsed: 00:00:00.36

SCOTT@test>select count(*) from ob where object_id=100;

Elapsed: 00:00:00.04

Execution Plan

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

Plan hash value: 2010433984

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

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

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

| 0 | SELECT STATEMENT | | 1 | 4 | 1 (0)| 00:00:01 |

| 1 | SORT AGGREGATE | | 1 | 4 | | |

|* 2 | INDEX RANGE SCAN| I_OB_ID | 1 | 4 | 1 (0)| 00:00:01 |

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

Predicate Information (identified by operation id):

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

2 - access("OBJECT_ID"=100)

Statistics

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

1 recursive calls

0 db block gets

2 consistent gets

0 physical reads

0 redo size

422 bytes sent via SQL*Net to client

419 bytes received via SQL*Net from client

2 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

1 rows processed

2. INDEX UNIQUE SCAN

SCOTT@test>drop index i_ob_id;

Index dropped.

Elapsed: 00:00:00.11

SCOTT@test>create unique index i_ob_id on ob(object_id);

Index created.

Elapsed: 00:00:00.27

SCOTT@test>select count(*) from ob where object_id=100;

Elapsed: 00:00:00.01

Execution Plan

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

Plan hash value: 3647361231

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

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

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

| 0 | SELECT STATEMENT | | 1 | 4 | 1 (0)| 00:00:01 |

| 1 | SORT AGGREGATE | | 1 | 4 | | |

|* 2 | INDEX UNIQUE SCAN| I_OB_ID | 1 | 4 | 1 (0)| 00:00:01 |

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

Predicate Information (identified by operation id):

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

2 - access("OBJECT_ID"=100)

Statistics

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

1 recursive calls

0 db block gets

2 consistent gets

1 physical reads

0 redo size

422 bytes sent via SQL*Net to client

419 bytes received via SQL*Net from client

2 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

1 rows processed

3. INDEX FAST FULL SCAN

SCOTT@test>select object_id from ob;

86789 rows selected.

Elapsed: 00:00:01.02

Execution Plan

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

Plan hash value: 1611727973

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

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

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

| 0 | SELECT STATEMENT | | 86789 | 339K| 346 (1)| 00:00:05 |

| 1 | TABLE ACCESS FULL| OB | 86789 | 339K| 346 (1)| 00:00:05 |

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

Statistics

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

1 recursive calls

0 db block gets

6924 consistent gets

0 physical reads

0 redo size

1262506 bytes sent via SQL*Net to client

64054 bytes received via SQL*Net from client

5787 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

86789 rows processed

SCOTT@test>alter table ob modify(object_id number constraint nn not null);

Table altered.

Elapsed: 00:00:00.16

SCOTT@test>select object_id from ob;

86789 rows selected.

Elapsed: 00:00:00.81

Execution Plan

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

Plan hash value: 2260539534

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

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

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

| 0 | SELECT STATEMENT | | 86789 | 339K| 51 (0)| 00:00:01 |

| 1 | INDEX FAST FULL SCAN| I_OB_ID | 86789 | 339K| 51 (0)| 00:00:01 |

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

Statistics

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

29 recursive calls

0 db block gets

5990 consistent gets

179 physical reads

0 redo size

1262506 bytes sent via SQL*Net to client

64054 bytes received via SQL*Net from client

5787 SQL*Net roundtrips to/from client

6 sorts (memory)

0 sorts (disk)

86789 rows processed

4. INDEX FULL SCAN

SCOTT@test>select object_id from ob order by 1;

86789 rows selected.

Elapsed: 00:00:00.85

Execution Plan

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

Plan hash value: 2425389225

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

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

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

| 0 | SELECT STATEMENT | | 86789 | 339K| 182 (1)| 00:00:03 |

| 1 | INDEX FULL SCAN | I_OB_ID | 86789 | 339K| 182 (1)| 00:00:03 |

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

Statistics

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

1 recursive calls

0 db block gets

5952 consistent gets

0 physical reads

0 redo size

1262506 bytes sent via SQL*Net to client

64054 bytes received via SQL*Net from client

5787 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

86789 rows processed

5. INDEX FULL SCAN DESCENDING

SCOTT@test>select object_id from ob order by 1 desc;

86789 rows selected.

Elapsed: 00:00:00.81

Execution Plan

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

Plan hash value: 606382278

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

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

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

| 0 | SELECT STATEMENT | | 86789 | 339K| 182 (1)| 00:00:03 |

| 1 | INDEX FULL SCAN DESCENDING| I_OB_ID | 86789 | 339K| 182 (1)| 00:00:03 |

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

Statistics

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

1 recursive calls

0 db block gets

5952 consistent gets

0 physical reads

0 redo size

1262506 bytes sent via SQL*Net to client

64054 bytes received via SQL*Net from client

5787 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

86789 rows processed

6. INDEX SKIP SCAN

SCOTT@test>create index i_ob2_2 on ob(owner,object_type,object_name);

Index created.

Elapsed: 00:00:00.53

SCOTT@test>analyze table ob compute statistics for all indexed columns;

Table analyzed.

Elapsed: 00:00:01.37

SCOTT@test>select owner,object_type,object_name from ob where object_type='RULE';

Elapsed: 00:00:00.01

Execution Plan

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

Plan hash value: 19331172

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

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

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

| 0 | SELECT STATEMENT | | 1 | 37 | 32 (0)| 00:00:01 |

|* 1 | INDEX SKIP SCAN | I_OB2_2 | 1 | 37 | 32 (0)| 00:00:01 |

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

Predicate Information (identified by operation id):

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

1 - access("OBJECT_TYPE"='RULE')

filter("OBJECT_TYPE"='RULE')

Statistics

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

1 recursive calls

0 db block gets

37 consistent gets

34 physical reads

0 redo size

567 bytes sent via SQL*Net to client

419 bytes received via SQL*Net from client

2 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

1 rows processed

SCOTT@test>spool off;