3. Oracle數據庫邏輯備份與恢復

一. Oracle邏輯備份介紹

　　Oracle邏輯備份的核心就是複製數據；Oracle提供的邏輯備份與恢復的命令有exp/imp，expdp/impdp。固然像表級複製(create table table_back as select * from table)也算是一種邏輯備份。Oracle邏輯備份沒有支持增量備份；對數據恢復也是非一致性的。因此通常都是用於數據遷移的工做。

　　建立演示對象

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導出/導入命令exp/imp

　　exp/imp命令是最原始的一種數據保護工具；效率方面確實很差；支持客戶端執行操做。在這簡單演示下如何操做。

　　備份的對象列表：

. 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 導出命令exp

• 導出表中某些記錄

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

• 導出某個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

• 導出哪些Schema下的對象

exp system/Oracle235 OWNER="(lottu,rax)"  FILE=/home/oracle/exp/system03.dmp LOG=/home/oracle/exp/log/system03.log

• 導出全庫

exp system/Oracle235 FULL=Y FILE=/home/oracle/exp/system04.dmp LOG=/home/oracle/exp/log/system04.log

2.2 導入命令imp

　　imp至關於exp的反向操做；操做以前；須要確認需導入的對象在數據庫上面是不存在的；如果在本地作恢復；須要將恢復的對象先drop掉；在執行imp命令操做。

• 導入某個Schema下某些表；對exp上面的示例2

[oracle@oracle235 ~]$ 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@oracle235 ~]$ 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導出/導入命令expdp/impdp

　　對expdp/impdp是在Oracle10G以後纔出現；其實自己使用並非須要很高的技術含量。相比exp/imp；在功能和效率方面有巨大的提高。

• 支持並行
• 支持任務的暫停和重啓動
• 支持對象的過濾

　　備份/恢復效率方面那是大大的提高。因此10G以後能夠棄用exp/imp。

　　empdp和impdp是服務端的工具程序，他們只能在ORACLE服務端使用，不能在客戶端使用；使用以前須要建立目錄；以下演示

• 在服務器上建立目錄

mkdir -p /data/ora_dir_lottu

• 建立邏輯目錄，給操做的用戶賦予在指定目錄的操做權限

create directory dp_lottu as '/data/ora_dir_lottu'; grant read,write on directory dp_lottu to lottu;

3.1 導出命令expdp

• 按表模式導出

expdp lottu/li0924  tables=tbl_lottu,tbl_lottu_01 dumpfile=expdp_lottu01.dmp logfile=expdp_lottu01.log directory=dp_lottu

• 按表空間導出

expdp "'/ as sysdba'" tablespaces=tp_lottu dumpfile=expdp_lottu02.dmp logfile=expdp_lottu02.log directory=dp_lottu job_name=lottu02

• 導出方案

expdp "'/ as sysdba'" SCHEMAS=lottu,rax dumpfile=expdp_lottu05.dmp logfile=expdp_lottu05.log directory=dp_lottu

• 導出整個數據庫

expdp "'/ as sysdba'" dumpfile=expdp_full.dmp full=y logfile=expdp_lottu05.log directory=dp_lottu

3.2 導入命令impdp

　　impdp至關於導入命令expdp的反向操做；使用方法跟expdp相同。至關於把上面expdp替換便可。

　　impdp導入的方案，表或者表空間與dump文件不一致；能夠用下列參數替換

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：#將lottu用戶下的數據所有導入到表空間tp_rax

impdp "'/ as sysdba'" directory=dp_lottu dumpfile=expdp_lottu04.dmp remap_tablespace=tp_lottu:tp_rax

四. 複製表

　　Oracle中複製表方式：

create table tablename_back as select * from tablename;