Oracle 将普通表转换为分区表
将普通表转换为区分表
一.利用原表重建分区表
SQL>create table yoon ( id number primary key ,time date );
Table created.
SQL>insert into yoon select rownum,created from dba_objects;
74930 rows created.
SQL>select count(*) from yoon;
COUNT(*)
----------
74930
SQL>create table yoon_new (ID,TIME) partition by range(time)
(partition p1 values less than (to_date('2011-10-01','YYYY-MM-DD')),
partition p2 values less than (to_date('2012-10-01','YYYY-MM-DD')),
partition p3 values less than (to_date('2013-10-01','YYYY-MM-DD')),
partition p4 values less than (MAXVALUE))
as select id,time from yoon;
Table created.
SQL>select table_owner,table_name,partition_name from dba_tab_partitions where table_name='YOON_NEW';
TABLE_OWNER TABLE_NAME PARTITION_NAME
------------------------------ ------------------------------ ------------------------------
YOON YOON_NEW P1
YOON YOON_NEW P2
YOON YOON_NEW P3
YOON YOON_NEW P4
SQL>alter table yoon rename to yoon_old;
Table altered.
SQL>alter table yoon_new rename to yoon;
Table altered.
SQL>select count(*) from yoon partition(p1);
COUNT(*)
----------
74445
SQL> select count(*) from yoon partition(p2);
COUNT(*)
----------
0
SQL> select count(*) from yoon partition(p3);
COUNT(*)
----------
0
SQL> select count(*) from yoon partition(p4);
COUNT(*)
----------
485
优点：方法简单、易用,由于采用DDL语句,不会产生UNDO,且只产生少量REDO,效率相对较高,而且建表完成后数据已经在分布到各个分区中了.
缺点：1.适用于修改不频繁的表,在闲时进行操作,表的数据量不宜太大.
2.表太大,在导入数据的时候会产生大量的UNDO;非要采用这种方式,将数据分批次导入.
二.交换分区
SQL> create table yoon ( id number primary key,time date ) ;
Table created.
SQL> insert into yoon select rownum,created from dba_objects;
74930 rows created.
SQL> commit;
Commit complete.
SQL> create table yoon_new ( id number primary key,time date ) partition by range(time)
2 (partition p1 values less than (to_date('2015-10-01','YYYY-DD-MM')),
3 partition p2 values less than (maxvalue));
Table created.
SQL> ALTER TABLE YOON_NEW EXCHANGE PARTITION P1 WITH TABLE YOON ;
Table altered.
SQL> select count(*) from yoon;
COUNT(*)
----------
0
SQL> select count(*) from yoon_new;
COUNT(*)
----------
74930
SQL> alter table yoon rename to yoon_old;
Table altered.
SQL> alter table yoon_new rename to yoon;
Table altered.
SQL> select table_owner,table_name,partition_name from dba_tab_partitions where table_name='YOON';
TABLE_OWNER TABLE_NAME PARTITION_NAME
------------------------------ ------------------------------ ------------------------------
YOON YOON P1
YOON YOON P2
三.在线重定义
SQL> create table yoon ( id number primary key,time date ) ;
Table created.
SQL> insert into yoon select rownum,created from dba_objects;
74930 rows created.
SQL> commit;
Commit complete.
SQL> EXEC DBMS_REDEFINITION.can_redef_table(user,'YOON',DBMS_REDEFINITION.CONS_USE_PK);
PL/SQL procedure successfully completed.
SQL> create table yoon_new ( id number primary key,time date ) partition by range(time)
2 (partition p1 values less than (to_date('2011-01-01','YYYY-DD-MM')),
3 partition p2 values less than (to_date('2012-01-01','YYYY-DD-MM')),
4 partition p3 values less than (to_date('2013-01-01','YYYY-DD-MM')),
5 partition p4 values less than (maxvalue));
Table created.
SQL> EXEC DBMS_REDEFINITION.START_REDEF_TABLE(USER,'YOON','YOON_NEW','ID ID,TIME TIME',DBMS_REDEFINITION.CONS_USE_PK);
PL/SQL procedure successfully completed.
SQL> EXEC DBMS_REDEFINITION.FINISH_REDEF_TABLE('YOON','YOON','YOON_NEW');
PL/SQL procedure successfully completed.
S
QL> select table_name from user_tables;
TABLE_NAME
------------------------------
YOON_NEW
YOON
SQL> select count(*) from yoon_new;
COUNT(*)
----------
74930
SQL> select count(*) from yoon;
COUNT(*)
----------
74930
SQL> select table_owner,table_name,partition_name from dba_tab_partitions where table_name='YOON';
TABLE_OWNER TABLE_NAME PARTITION_NAME
------------------------------ ------------------------------ ------------------------------
YOON YOON P1
YOON YOON P2
YOON YOON P3
YOON YOON P4
在线重定义能够保证数据的一致性,在大部分时间中,表YOON都可以正常进行DML操作,在切换的瞬间锁表,具有狠高的可用性,具有狠强的灵活性,能够满足各种不同的需求.可以在切换前建立各种约束,做到切换后不用任何额外的管理操作.