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Oracle数据库逻辑备份与恢复

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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;

更多 Oracle 相关信息见Oracle 专题页面 https://www.linuxidc.com/topicnews.aspx?tid=12

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