Datapump Scenarios - Frequently Asked

Q. How to split the datapump dumpfiles, into multiple and at multiple directories ?

PARALLEL parameter is used to improve the speed of the export.

This will be also more effective if you split the dumpfiles with DUMPFILE parameter across the filesystem.

Create 2 or 3 directories in different filesystems and use the commands effectively.

$ expdp / dumpfile=dir1:test_1.dmp, dir1:test_2.dmp, dir2:test_3.dmp, dir3:test_4.dmp logfile=dir1:test.log  full=y parallel=4

Q. How to limit the file size of dumpfile in Datapump ?

FILESIZE parameter is used to limit the dumpfile size. For eg., if you want to limit your dumpfiles to 5gb,  you can issue command as below

$ expdp / directory=dir1 dumpfile=test_%U.dmp logfile=test.log filesize=5120m full=y

where %U will assign numbers automatically from 1 to 99.

Q. How to import the dumpfile if the Database version are not same ?

VERSION parameter is used while taking export if you want to create a dumpfile which should be imported  into a DB which is lower than the source DB

Example:

If your source DB is 11g and target DB is 10g, you can't use the dumpfile taken from 11g expdp utility to import into 10g DB.

If you don’t use this VERSION parameter, then it will show you the error as Below

ORA-39142: incompatible version number 3.1 in dump file "/u01/datapump/test.dmp"

VERSION={COMPATIBLE | LATEST | version_string}

$ expdp / directory=dir1 dumpfile=test_1.dmp logfile=test.log VERSION=10.2.0

Q. How to improve the performace of Datapump while Importing ?

1) Import of full database should be split as tables first and indexes next. Use the parameter exclude  effectively to improve the speed of import.

EXCLUDE = INDEX,STATISTICS

This will not import the indexes and statistics which in turn only import the tables, hence improving the performance

2)Always set init.ora parameter cursor_sharing to exact which has a good effect on import's performance.

Q. How to find the contents of a dumpfile ?

If you are not sure about the schemas that were present in the dumpfile or tablespaces present inside the  dumpfile, etc., you can easily check the dumpfile for those information.

Use the below command

$  grep -a "CREATE USER" test_1.dmp

$  grep -a "CREATE TABLESPACE" test_1.dmp

The above command gives all the CREATE USER statements and CREATE TABLESPACE statements

which will be useful in many cases.

Note: You can also get the INDEXES and TABLES creation ddl from the dumpfile as well.

I’ll be updating the post whenever I come across things that can help improving the performance of datapump. 

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