在Oracle 11g上，可以在虚拟列上做分区，这个特性还比较有用，下面来做一个测试：
SQL> select * from v$version;
BANNER
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Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
PL/SQL Release 11.2.0.1.0 - Production
CORE 11.2.0.1.0 Production
TNS for Linux: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production
SQL> drop table test purge;
SQL> create table test
(bureau_code varchar2(20) not null,
province_code as (CAST(SUBSTR(bureau_code,0,2) AS VARCHAR2(2)))
)
partition by list (province_code)
(
partition p1 values ('01'),
partition p2 values ('02'),
partition p3 values ('03'),
partition p4 values ('04'),
partition p5 values ('05')
);
SQL> insert into test(bureau_code) values('0101');
SQL> insert into test(bureau_code) values('0102');
SQL> insert into test(bureau_code) values('0202');
SQL> insert into test(bureau_code) values('0202');
SQL> insert into test(bureau_code) values('0302');
SQL> insert into test(bureau_code) values('0302');
SQL> insert into test(bureau_code) values('0402');
SQL> insert into test(bureau_code) values('0502');
SQL> commit;
SQL> select * from test partition(p1);
BUREAU_CODE PR
-------------------- --
0101 01
0102 01
SQL> set autotrace traceonly
SQL> select * from test partition(p1);
执行计划
----------------------------------------------------------
Plan hash value: 213508695
----------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |
----------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 2 | 30 | 4 (0)| 00:00:01 | | |
| 1 | PARTITION LIST SINGLE| | 2 | 30 | 4 (0)| 00:00:01 | 1 | 1 |
| 2 | TABLE ACCESS FULL | TEST | 2 | 30 | 4 (0)| 00:00:01 | 1 | 1 |--证明是走了分区的
----------------------------------------------------------------------------------------------
Note
-----
- dynamic sampling used for this statement (level=2)
统计信息
----------------------------------------------------------
0 recursive calls
0 db block gets
8 consistent gets
0 physical reads
0 redo size
434 bytes sent via SQL*Net to client
338 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
2 rows processed