| 很多数据库在设计时未能很好的规划数据库的容量, 导致在某些情况下, 导致一个表中存放了数百万, 数千万甚至上亿条记录, 维护起来非常的不便, 下面介绍一种将非分区表转换为分区表的方法.
testtb_nopart是一个非分区表, 基本信息如下:
SQL> desc testtb_nopart
Name Null? Type
----------------------------------------- -------- ----------------------------
TIMESTAMP DATE
OWNER VARCHAR2(30)
ACTION VARCHAR2(6)
OBJECT_NAME VARCHAR2(128)
MESSENG VARCHAR2(169)
SQL> select to_char(timestamp, 'mm-yyyy'), count(*) from testtb_nopart group by to_char(timestamp, 'mm-yyyy');
TO_CHAR COUNT(*)
------- ----------
12-2005 2058125
11-2005 1363431
08-2005 150951
10-2005 628149
07-2005 1006340
09-2005 730410
6 rows selected.
创建分区表testtb_part, 结构和testtb_nopart一致.
create table testtb_part (timestamp date, owner varchar2(30), action varchar2(6), object_name varchar2(128) , messeng varchar2(169))
tablespace testts
partition by range(timestamp)(
partition rest values less than (maxvalue))
交换testtb_nopart和testtb_part中part分区的数据
SQL> alter table testtb_part exchange partition rest with table testtb_nopart;
Table altered.
SQL> select to_char(timestamp, 'mm-yyyy'), count(*) from testtb_nopart group by to_char(timestamp, 'mm-yyyy');
no rows selected
SQL> c/nopart/part/
1* select to_char(timestamp, 'mm-yyyy'), count(*) from testtb_part group by to_char(timestamp, 'mm-yyyy')
SQL> /
TO_CHAR COUNT(*)
------- ----------
12-2005 2058125
11-2005 1363431
08-2005 150951
10-2005 628149
07-2005 1006340
09-2005 730410
6 rows selected.
testtb_nopart中大约有50万条记录, 占用600m左右空间, 交换大约用了不到30秒钟, testtb_part和testtb_nopart所在的表空间也没有明显增长.
对rest分区进行拆分
SQL> alter table testtb_part split partition rest at (to_date('200508','yyyymm'))
2 into (partition part08, partition rest);
Table altered.
SQL> alter table testtb_part split partition rest at (to_date('200509','yyyymm'))
2 into (partition part08, partition rest);
Table altered.
SQL> alter table testtb_part split partition rest at (to_date('200510','yyyymm'))
2 into (partition part09, partition rest);
Table altered.
SQL> alter table testtb_part split partition rest at (to_date('200511','yyyymm'))
2 into (partition part10, partition rest);
Table altered.
SQL> alter table testtb_part split partition rest at (to_date('200512','yyyymm'))
2 into (partition part11, partition rest);
Table altered.
SQL> alter table testtb_part split partition rest at (to_date('200601','yyyymm'))
2 into (partition part12, partition rest);
Table altered.
最后可以重命名表, 使得转换过程不影响用户程序.
alter table testtb_part rename to testtb_nopart
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