Oracle全文索引的性能优势实例 - 数据库编程

一、实验说明：

操作系统：rhel 5.4 x86

二、操作步骤：

2.1、首先创建一个表t_btree，并创建B-Tree索引，索引键是object_name:

SQL> create table t_btree as select * from dba_objects;

Table created.

SQL> create index ind_btree on t_btree(object_name);

Index created.

接着是执行下面的查询语句两次：

SQL> set linesize 150;
SQL> set autotrace on;
SQL> select count(*) from t_btree where t_btree.object_name like '%ObjectStreamClass%';

COUNT(*)
----------
84

Execution Plan
----------------------------------------------------------
Plan hash value: 3266099700

-----------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
-----------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 66 | 103 (0)| 00:00:02 |
| 1 | SORT AGGREGATE | | 1 | 66 | | |
|* 2 | INDEX FAST FULL SCAN| IND_BTREE | 12 | 792 | 103 (0)| 00:00:02 |
-----------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

2 - filter("T_BTREE"."OBJECT_NAME" IS NOT NULL AND
"T_BTREE"."OBJECT_NAME" LIKE '%ObjectStreamClass%')

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

Statistics
----------------------------------------------------------
28 recursive calls
0 db block gets
454 consistent gets
726 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

SQL> select count(*) from t_btree where t_btree.object_name like '%ObjectStreamClass%';

COUNT(*)
----------
84

Execution Plan
----------------------------------------------------------
Plan hash value: 3266099700

Predicate Information (identified by operation id):
---------------------------------------------------

2 - filter("T_BTREE"."OBJECT_NAME" IS NOT NULL AND
"T_BTREE"."OBJECT_NAME" LIKE '%ObjectStreamClass%')

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

Statistics
----------------------------------------------------------
0 recursive calls
0 db block gets
369 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

2.2、创建表t_bmap，并创建BitMap索引：

1 SQL> create table t_bmap as select * from dba_objects;
2
3 Table created.
4 SQL> create bitmap index ind_bmap on t_bmap(object_name);
5
6 Index created。

执行之前的同样的语句查询：

SQL> select count(*) from t_bmap where t_bmap.object_name like '%ObjectStreamClass%';

COUNT(*)
----------
84

Execution Plan
-----

Oracle全文索引的性能优势实例(一)