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概要
Oracle 11g及以上版本提供了数据泵技术，可以用来进行数据库的逻辑备份和恢复，Oracle建议使用数据泵来代替EXP和IMP技术。数据泵技术基于Oracle数据库服务器，导入导出的数据文件也保存在数据库服务器端，而EXP/IMP基于客户机运行。利用数据泵技术，Oracle要求必须使用目录对象，以防止用户误操作服务器上特定目录下的操作系统文件。
EXPDP数据访问方法
外部表：从操作系统文件中读取数据；
直接路径：使用直接路径API，很好改善了导入导出性能，因为内部流的数据格式和存储在备份文件中的数据格式相同，减少了数据转换的时间。
查询默认的目录对象
SQL> set linesize 200
SQL> SELECT * FROM dba_directories t
2 WHERE t.directory_name = 'DATA_PUMP_DIR';
OWNER DIRECTORY_NAME DIRECTORY_PATH
------------------------------ ------------------------------ -----------------------------------
SYS DATA_PUMP_DIR E:\app\alen.liu\admin\orcl\dpdump\
创建恢复目录需要CREATE ANY DIRECTORY权限；
SQL> grant create any directory to scott;
Grant succeeded.
SQL> alter session set current_schema=scott;
Session altered.
SQL> create directory scott_pump as 'd:\pump';
Directory created.
SQL>
EXPDP导出技术演示
EXPDP参数
D:\backup>expdp help=y
Export: Release 11.2.0.1.0 - Production on Tue Jun 27 17:13:24 2017
Copyright (c) 1982, 2009, Oracle and/or its affiliates. All rights reserved.
The Data Pump export utility provides a mechanism for transferring data objects
between Oracle databases. The utility is invoked with the following command:
Example: expdp scott/tiger DIRECTORY=dmpdir DUMPFILE=scott.dmp
You can control how Export runs by entering the 'expdp' command followed
by various parameters. To specify parameters, you use keywords:
Format: expdp KEYWORD=value or KEYWORD=(value1,value2,...,valueN)
Example: expdp scott/tiger DUMPFILE=scott.dmp DIRECTORY=dmpdir SCHEMAS=scott
or TABLES=(T1:P1,T1:P2), if T1 is partitioned table
USERID must be the first parameter on the command line.
------------------------------------------------------------------------------
The available keywords and their descriptions follow. Default values are listed within square brackets.
ATTACH
Attach to an existing job.
For example, ATTACH=job_name.
COMPRESSION
Reduce the size of a dump file.
Valid keyword values are: ALL, DATA_ONLY, [METADATA_ONLY] and NONE.
CONTENT
Specifies data to unload.
Valid keyword values are: [ALL], DATA_ONLY and METADATA_ONLY.
DATA_OPTIONS
Data layer option flags.
Valid keyword values are: XML_CLOBS.
DIRECTORY
Directory object to be used for dump and log files.
DUMPFILE
Specify list of destination dump file names [expdat.dmp].
For example, DUMPFILE=scott1.dmp, scott2.dmp, dmpdir:scott3.dmp.
ENCRYPTION
Encrypt part or all of a dump file.
Valid keyword values are: ALL, DATA_ONLY, ENCRYPTED_COLUMNS_ONLY, METADATA_ONLY and NONE.
ENCRYPTION_ALGORITHM
Specify how encryption should be done.
Valid keyword values are: [AES128], AES192 and AES256.
ENCRYPTION_MODE
Method of generating encryption key.
Valid keyword values are: DUAL, PASSWORD and [TRANSPARENT].
ENCRYPTION_PASSWORD
Password key for creating encrypted data within a dump file.
ESTIMATE
Calculate job estimates.
Valid keyword values are: [BLOCKS] and STATISTICS.
ESTIMATE_ONLY
Calculate job estimates without performing the export.
EXCLUDE
Exclude specific object types.
For example, EXCLUDE=SCHEMA:"='HR'".
FILESIZE
Specify the size of each dump file in units of bytes.
FLASHBACK_SCN
SCN used to reset session snapshot.
FLASHBACK_TIME
Time used to
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