比较数据泵和exp/imp对相同数据导出/导入的性能差异
create table test as select * from dba_objects where rownum<10001;
begin
for i in 1 .. 7 loop
insert into test select * from test;
commit;
end loop;
end;
BYS@ bys001>select count(*) from test;
COUNT(*)
----------
1280000
Elapsed: 00:00:01.12
BYS@ bys001>select segment_name,segment_type,tablespace_name,extents,bytes/1024/1024 MB,owner from dba_segments where segment_name='TEST' and owner='BYS';
SEGMENT_NAME SEGMENT_TYPE TABLESPACE_NAME EXTENTS MB OWNER
--------------- ------------------ --------------- ---------- ---------- ----------
TEST TABLE USERS 98 216 BYS
[oracle@oel-01 ~]$ exp bys/bys file='/home/oracle/test.dmp' tables=test rows=y
Export: Release 11.2.0.1.0 - Production on Mon Jul 29 17:01:48 2013
Copyright (c) 1982, 2009, Oracle and/or its affiliates. All rights reserved.
Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
Export done in US7ASCII character set and AL16UTF16 NCHAR character set
server uses AL32UTF8 character set (possible charset conversion)
About to export specified tables via Conventional Path ...
. . exporting table TEST 1280000 rows exported
Export terminated successfully without warnings.
[oracle@oel-01 ~]$ date
Mon Jul 29 17:02:18 CST 2013
要创建 exp_dump目录并在数据库中指定。
[oracle@oel-01 ~]$ mkdir exp_dump
BYS@ bys001>create directory exp_dump as '/home/oracle/exp_dump';
Directory created.
Elapsed: 00:00:01.14
[oracle@oel-01 exp_dump]$
Export: Release 11.2.0.1.0 - Production on Mon Jul 29
Copyright (c) 1982, 2009, Oracle and/or its affiliates. All rights reserved.
Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
Legacy Mode Active due to the following parameters:
Legacy Mode Parameter: "file=test.dmp" Location: Command Line, Replaced with: "dumpfile=test.dmp"
Legacy Mode has set reuse_dumpfiles=true parameter.
Starting "BYS"."SYS_EXPORT_TABLE_01": bys/******** directory=exp_dump dumpfile=test.dmp tables=test reuse_dumpfiles=true
Estimate in progress using BLOCKS method...
Processing object type TABLE_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 136 MB
Processing object type TABLE_EXPORT/TABLE/TABLE
. . exported "BYS"."TEST" 111.6 MB 1280000 rows
Master table "BYS"."SYS_EXPORT_TABLE_01" successfully loaded/unloaded
******************************************************************************
Dump file set for BYS.SYS_EXPORT_TABLE_01 is:
/home/oracle/exp_dump/test.dmp
Job "BYS"."SYS_EXPORT_TABLE_01" successfully completed at
########################
BYS@ bys001>truncate table test;
Table truncated.
Elapsed: 00:00:00.16
Import: Release 11.2.0.1.0 - Production on Mon Jul 29 17:21:16 2013
Copyright (c) 1982, 2009, Oracle and/or its affiliates. All rights reserved.
Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 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 US7ASCII character set and AL16UTF16 NCHAR character set
import server uses AL32UTF8 character set (possible charset conversion)
. importing BYS's objects into BYS
. importing BYS's objects into BYS
. . importing table "TEST" 1280000 rows imported
Import terminated successfully without warnings.
[oracle@oel-01 ~]$ date
Mon Jul 29 17:22:55 CST 2013
BYS@ bys001>truncate table test;
Table truncated.
Elapsed: 00:00:00.12
BYS@ bys001>drop table test purge;
Table dropped.
Elapsed: 00:00:00.05
[oracle@oel-01 exp_dump]$
Import: Release 11.2.0.1.0 - Production on Mon Jul 29 17:39:08 2013
Copyright (c) 1982, 2009, Oracle and/or its affiliates. All rights reserved.
Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
Master table "BYS"."SYS_IMPORT_FULL_01" successfully loaded/unloaded
Starting "BYS"."SYS_IMPORT_FULL_01": bys/******** directory=exp_dump dumpfile=test.dmp
Processing object type TABLE_EXPORT/TABLE/TABLE
Processing object type TABLE_EXPORT/TABLE/TABLE_DATA
. . imported "BYS"."TEST" 111.6 MB 1280000 rows
Job "BYS"."SYS_IMPORT_FULL_01" successfully completed at 17:40:28
EXPDP/IMPDP是Oracle推荐的数据泵导入导出工具，用于代替传统的EXP/IMP，只能在服务端使用，效率比EXP/IMP快几十倍，有续传功能和并行功能。
这个工具始于Oracle10g，从Oracle11g开始不再提供老的EXP/IMP的咨询但工具还可以使用。
EXPDP工具的效率差不多比EXP快几倍，IMPDP工具的效率差不多比IMP快几十倍，这两个工具适用于大数据导入导出的场景。
导出文件的格式更接近于数据库本身的文件格式，避免了数据写入文件时的转换
直接路径加载，跳过SGA内存区，直接加载到高水位线之后
元数据metadata和数据data在导出的过程中可以重叠进行，提高导出的效率。
在使用EXPDP/IMPDP之前需要定义一个目录对象，告知EXPDP/IMPDP工具导出的文件和导入的文件的存放目录
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