Oracle全文索引的性能优势实例(2)

日期：2020-06-06 栏目：程序人生浏览：次

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
----------------------------------------------------------
Plan hash value: 891302759

------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 66 | 263 (0)| 00:00:04 |
| 1 | SORT AGGREGATE | | 1 | 66 | | |
| 2 | BITMAP CONVERSION COUNT | | 12 | 792 | 263 (0)| 00:00:04 |
|* 3 | BITMAP INDEX FAST FULL SCAN| IND_BMAP | | | | |
------------------------------------------------------------------------------------------

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

3 - filter("T_BMAP"."OBJECT_NAME" IS NOT NULL AND "T_BMAP"."OBJECT_NAME" LIKE
'%ObjectStreamClass%')

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

Statistics
----------------------------------------------------------
28 recursive calls
0 db block gets
360 consistent gets
591 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