数据泵卸载
Oracle9i引入了外部表,作为向数据库中读取数据的一种方法.Oracle 10g则从另一个方向引入了这个特性,可以使用CREATE TABLE语句创建外部数据,从而由数据库卸载数据.从Oracle 10g起,这个数据从一种专用二进制格式抽取,这种格式称为数据 泵格式(Data Pump format),Oracle提供的EXPDP和IMPDP工具将数据从一个数据库移动另一个数据库所用的就是这种格式.
使用外部表卸载确实相当容易,就像使用CREATE TABLE AS SELECT语句一样简单.首先,需要一个DIRECTORY对象:
jy@JINGYONG> create or replace directory dir1 as '/home/oracle'; 目录已创建。
现在,准备使用一个简单的SELECT语句向这个目录中卸载数据,例如:
jy@JINGYONG> create table my_object_unload
2 organization external
3 (
4 type oracle_datapump
5 default directory DIR1
6 location('myobjects.dat')
7 )
8 as
9 select * from all_objects;
表已创建。
[oracle@jy ~]$ ls -lrt myobjects.dat
-rw-r----- 1 oracle oinstall 4923392 Oct 5 04:09 myobjects.dat
从上面的信息可知已经生成了myobjects.dat文件
获取外部表my_object_unload的创建语句
SQL> select dbms_metadata.get_ddl( 'TABLE', 'MY_OBJECT_UNLOAD' ) from dual;
DBMS_METADATA.GET_DDL('TABLE',
--------------------------------------------------------------------------------
CREATE TABLE "JY"."MY_OBJECT_UNLOAD"
( "OWNER" VARCHAR2(30),
"OBJECT_NAME" VARCHAR2(30),
"SUBOBJECT_NAME" VARCHAR2(30),
"OBJECT_ID" NUMBER,
"DATA_OBJECT_ID" NUMBER,
"OBJECT_TYPE" VARCHAR2(19),
"CREATED" DATE,
"LAST_DDL_TIME" DATE,
"TIMESTAMP" VARCHAR2(19),
"STATUS" VARCHAR2(7),
"TEMPORARY" VARCHAR2(1),
"GENERATED" VARCHAR2(1),
"SECONDARY" VARCHAR2(1)
)
ORGANIZATION EXTERNAL
( TYPE ORACLE_DATAPUMP
DEFAULT DIRECTORY "DIR1"
LOCATION
( 'myobjects.dat'
)
)
现在把生成的myobjects.dat文件拷贝到你要加载数据的服务器上创建目录(directory)并在要加载数据的用户下使用上面创建外部表的语句(记得要修改DEFAULT DIRECTORY “DIR1″指向你所存放myobjects.dat的目录)来创建外部表
CREATE TABLE "MY_OBJECT_UNLOAD"
( "OWNER" VARCHAR2(30),
"OBJECT_NAME" VARCHAR2(30),
"SUBOBJECT_NAME" VARCHAR2(30),
"OBJECT_ID" NUMBER,
"DATA_OBJECT_ID" NUMBER,
"OBJECT_TYPE" VARCHAR2(19),
"CREATED" DATE,
"LAST_DDL_TIME" DATE,
"TIMESTAMP" VARCHAR2(19),
"STATUS" VARCHAR2(7),
"TEMPORARY" VARCHAR2(1),
"GENERATED" VARCHAR2(1),
"SECONDARY" VARCHAR2(1)
)
ORGANIZATION EXTERNAL
( TYPE ORACLE_DATAPUMP
DEFAULT DIRECTORY "DIR1"
LOCATION
( 'myobjects.dat'
)
);
/
SQL> select * from my_object_unload ;
OWNER OBJECT_NAME SUBOBJECT_NAME OBJECT_ID DATA_OBJECT_ID OBJECT_TYPE CREATED LAST_DDL_TIME TIMESTAMP STATUS TEMPORARY GENERATED SECONDARY
------- ---------------------- -------------- ---------- -------------- ------------------- ----------- ------- ------ ------------------- ------- --------- --------- ---------
SYS ICOL$ 20 2 TABLE 2005-6-30 1 2005-6- 30 19: 2005-06-30:19:10:16 VALID N N N
SYS I_USER1 44 44 INDEX 2005-6-30 1 2005-6- 30 19: 2005-06-30:19:10:16 VALID N N N
SYS CON$ 28 28 TABLE 2005-6-30 1 2013-3- 24 12: 2005-06-30:19:10:16 VALID N N N
SYS UNDO$ 15 15 TABLE 2005-6-30 1 2005-6- 30 19: 2005-06-30:19:10:16 VALID N N N
SYS C_COBJ# 29 29 CLUSTER 2005-6-30 1 2005-6- 30 19: 2005-06-30:19:10:16 VALID N N N
SYS I_OBJ# 3 3 INDEX 2005-6-30 1 2005-6- 30 19: 2005-06-30:19:10:16 VALID N N N
SYS PROXY_ROLE_DATA$ 25 25 TABLE 2005-6-30 1 2005-6- 30 19: 2005-06-30:19:10:16 VALID N N N
SYS I_IND1 39 39 INDEX 2005-6-30 1 2005-6- 30 19: 2005-06-30:19:10:16 VALID N N N
SYS I_CDEF2 51 51 INDEX 2005-6-30 1 2005-6- 30 19: 2005-06-30:19:10:16 VALID N N N
SYS I_PROXY_ROLE_DATA$_1 26 26 INDEX 2005-6-30 1 2005-6- 30 19: 2005-06-30:19:10:16 VALID N N N