oracle 9i提供了dbms_redefinition包来实现数据库的表的在线重定义功能。在实际的应用上，我们可以利用这个包来进行：

(1)堆表与分区之间进行转换。(2)重建表以减少HWM。10g能shrink，9i如果用move tablespace and rebuild index在move的时候会锁表，如果想实现在线降低HWM，只能用这个了。

(3)在线更改表结构，如更改列的前后顺序，将column_a，column_b改成column_b，column_a

1.创建测试表

create table rebuild_table as select * from dba_objects;

insert into rebuild_table select * from rebuild_table;

insert into rebuild_table select * from rebuild_table;

insert into rebuild_table select * from rebuild_table;

commit；

delete from rebuild_table;

insert into rebuild_table select * from dba_objects;

insert into rebuild_table select * from rebuild_table;

insert into rebuild_table select * from rebuild_table;

commit;

update rebuild_table set object_id=rownum;

alter  table rebuild_table add CONSTRAINT P_YY PRIMARY KEY (OBJECT_ID);

select * from rebuild_table;

2.创建分区表

create table REBUILD_PA_TABLE

(

STATIS_DATE    NUMBER(8),

OWNER          VARCHAR2(30),

OBJECT_NAME    VARCHAR2(128),

SUBOBJECT_NAME VARCHAR2(30),

OBJECT_ID      NUMBER not null,

DATA_OBJECT_ID NUMBER,

OBJECT_TYPE    VARCHAR2(18),

CREATED        DATE,

LAST_DDL_TIME  DATE,

TIMESTAMP      VARCHAR2(19),

STATUS         VARCHAR2(7),

TEMPORARY      VARCHAR2(1),

GENERATED      VARCHAR2(1),

SECONDARY      VARCHAR2(1)

)

partition by  list (STATIS_DATE)

(

partition p20111031 values (20111031)

);

alter table REBUILD_PA_TABLE add partition p20111101 values(20111101);

;

alter table REBUILD_PA_TABLE

add constraint Pa_YYY primary key (OBJECT_ID)

;

-- 打开重定义

begin

dbms_redefinition.CAN_REDEF_TABLE('boc_rdm','REBUILD_TABLE');

end;

-- 开始重定义

begin

dbms_redefinition.START_REDEF_TABLE('boc_rdm','REBUILD_TABLE','REBUILD_PA_TABLE');

end;

-- 进行数据同步

begin

dbms_redefinition.sync_interim_table('BOC_RDM','REBUILD_TABLE','REBUILD_PA_TABLE');

end;

-- 重命名表，把非分区表转化为分区表

begin

dbms_redefinition.finish_redef_table('BOC_RDM','REBUILD_TABLE','REBUILD_PA_TABLE');

end;

select * from REBUILD_TABLE partition(p20111031)