Oracle逻辑备份的核心就是复制数据；Oracle提供的逻辑备份与恢复的命令有exp/imp，expdp/impdp。当然像表级复制(create table table_back as select * from table)也算是一种逻辑备份。Oracle逻辑备份没有支持增量备份；对数据恢复也是非一致性的。所以一般都是用于数据迁移的工作。
创建演示对象
create tablespace lottu datafile '/data/oracle/data/lottu01.dbf' size 2G autoextend on; create user lottu identified by li0924 default tablespace lottu; grant connect, resource to lottu ; grant select any dictionary to lottu ; create user rax identified by rax123 default tablespace lottu; grant connect, resource to rax ; grant select any dictionary to rax ; conn lottu/li0924 create table tbl_lottu as select level as id, 'lottu' as name from dual connect by level <= 10000; create table tbl_lottu_01 as select level as id, 'lottu'||level as name from dual connect by level <= 100; conn rax/rax123 create table tbl_rax as select level as id, 'rax' as name from dual connect by level <= 10000;
二. Oracle导出/导入命令exp/imp
exp/imp命令是最原始的一种数据保护工具；效率方面确实不好；支持客户端执行操作。在这简单演示下如何操作。
备份的对象列表：
. exporting tablespace definitions . exporting profiles . exporting user definitions . exporting roles . exporting resource costs . exporting rollback segment definitions . exporting database links . exporting sequence numbers . exporting directory aliases . exporting context namespaces . exporting foreign function library names . exporting PUBLIC type synonyms . exporting private type synonyms . exporting object type definitions . exporting system procedural objects and actions . exporting pre-schema procedural objects and actions . exporting cluster definitions
2.1 导出命令exp
- 导出表中某些记录
exp lottu/li0924 GRANTS=Y TABLES=tbl_lottu QUERY="'where id < 100'" FILE=/home/oracle/exp/lottu01.dmp LOG=/home/oracle/exp/log/lottu01.log
- 导出某个Schema下某些表
exp lottu/li0924 GRANTS=Y TABLES="(tbl_lottu,tbl_lottu_01)" FILE=/home/oracle/exp/lottu02.dmp LOG=/home/oracle/exp/log/lottu02.log
- 导出哪些Schema下的对象
exp system/oracle-linuxidc OWNER="(lottu,rax)" FILE=/home/oracle/exp/system03.dmp LOG=/home/oracle/exp/log/system03.log
- 导出全库
exp system/oracle-linuxidc FULL=Y FILE=/home/oracle/exp/system04.dmp LOG=/home/oracle/exp/log/system04.log
2.2 导入命令imp
imp相当于exp的反向操作；操作之前；需要确认需导入的对象在数据库上面是不存在的；若是在本地做恢复；需要将恢复的对象先drop掉；在执行imp命令操作。
- 导入某个Schema下某些表；对exp上面的示例2
[oracle@oracle-linuxidc ~]$ sqlplus lottu/li0924
SQL*Plus: Release 11.2.0.4.0 Production on Sat Aug 4 04:42:18 2018
Copyright (c) 1982, 2013, Oracle. All rights reserved.
Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> drop table tbl_lottu;
Table dropped.
SQL> drop table tbl_lottu_01;
Table dropped.
SQL> exit Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options [oracle@oracle-linuxidc ~]$ imp lottu/li0924 GRANTS=Y TABLES="(tbl_lottu,tbl_lottu_01)" FILE=/home/oracle/exp/lottu02.dmp LOG=/home/oracle/imp/lottu02.log
Import: Release 11.2.0.4.0 - Production on Sat Aug 4 04:43:25 2018
Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.
Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options
Export file created by EXPORT:V11.02.00 via conventional path import done in UTF8 character set and UTF8 NCHAR character set export server uses AL16UTF16 NCHAR character set (possible ncharset conversion) . importing LOTTU's objects into LOTTU . importing LOTTU's objects into LOTTU . . importing table "TBL_LOTTU" 10000 rows imported . . importing table "TBL_LOTTU_01" 100 rows imported Import terminated successfully without warnings.
三. Oracle导出/导入命令expdp/impdp
对expdp/impdp是在Oracle10G之后才出现；其实本身使用并不是需要很高的技术含量。相比exp/imp；在功能和效率方面有巨大的提升。
- 支持并行
- 支持任务的暂停和重启动
- 支持对象的过滤
备份/恢复效率方面那是大大的提升。所以10G之后可以弃用exp/imp。
empdp和impdp是服务端的工具程序，他们只能在ORACLE服务端使用，不能在客户端使用；使用之前需要创建目录；如下演示
- 在服务器上创建目录
mkdir -p /data/ora_dir_lottu
- 创建逻辑目录，给操作的用户赋予在指定目录的操作权限
create directory dp_lottu as '/data/ora_dir_lottu'; grant read,write on directory dp_lottu to lottu;
3.1 导出命令expdp
- 按表模式导出
expdp lottu/li0924 tables=tbl_lottu,tbl_lottu_01 dumpfile=expdp_lottu01.dmp logfile=expdp_lottu01.log directory=dp_lottu
- 按表空间导出
expdp "'/ as sysdba'" tablespaces=tp_lottu dumpfile=expdp_lottu02.dmp logfile=expdp_lottu02.log directory=dp_lottu job_name=lottu02
- 导出方案
expdp "'/ as sysdba'" SCHEMAS=lottu,rax dumpfile=expdp_lottu05.dmp logfile=expdp_lottu05.log directory=dp_lottu
- 导出整个数据库
expdp "'/ as sysdba'" dumpfile=expdp_full.dmp full=y logfile=expdp_lottu05.log directory=dp_lottu
3.2 导入命令impdp
impdp相当于导入命令expdp的反向操作；使用方法跟expdp相同。相当于把上面expdp替换即可。
impdp导入的方案，表或者表空间与dump文件不一致；可以用下列参数替换
REMAP_SCHEMA Objects from one schema are loaded into another schema.
REMAP_TABLE Table names are remapped to another table. For example, REMAP_TABLE=HR.EMPLOYEES:EMPS.
REMAP_TABLESPACE Tablespace objects are remapped to another tablespace.
如示例所示：#将lottu用户下的数据全部导入到表空间tp_rax
impdp "'/ as sysdba'" directory=dp_lottu dumpfile=expdp_lottu04.dmp remap_tablespace=tp_lottu:tp_rax
四. 复制表
Oracle中复制表方式：
create table tablename_back as select * from tablename;
