Data Pump

Introduction
Oracle Data Pump is the replacement for the original Export and Import utilities.
Available starting in Oracle Database 10g, Oracle Data Pump enables very high-speed
movement of data and metadata from one database to another.

The Data Pump Export and Import utilities have a similar look and feel to the original
utilities, but they are much more efficient and give you greater control and management
of your import and export jobs.

This paper gives users of the original Export and Import utilities a primer on how to move
up to the faster, more powerful, and more flexible Data Pump Export and Import utilities.

See the Oracle Database Utilities Guide for more comprehensive information about
Oracle Data Pump.

New Concepts in Oracle Data Pump

There are two new concepts in Oracle Data Pump that are different from original Export and
Import.

Directory Objects

Data Pump differs from original Export and Import in that all jobs run primarily on the server
using server processes. These server processes access files for the Data Pump jobs using
directory objects that identify the location of the files. The directory objects enforce a security
model that can be used by DBAs to control access to these files.

Interactive Command-Line Mode

Besides regular operating system command-line mode, there is now a very powerful interactive
command-line mode which allows the user to monitor and control Data Pump Export and
Import operations.

Changing from Original Export/Import to Oracle Data Pump

Creating Directory Objects

In order to use Data Pump, the database administrator must create a directory object and grant

privileges to the user on that directory object. If a directory object is not specified, a default

directory object called data_pump_dir is provided. The default data_pump_dir is available only

to privileged users unless access is granted by the DBA.

In the following example, the following SQL statement creates a directory object named

dpump_dir1 that is mapped to a directory located at /usr/apps/datafiles.

create a directory.

1. SQL> CREATE DIRECTORY dpump_dir1 AS ‘/usr/apps/datafiles’;

After a directory is created, you need to grant READ and WRITE permission on the directory

to other users. For example, to allow the Oracle database to read and to write to files on behalf

of user scott in the directory named by dpump_dir1, you must execute the following

command.

2. SQL> GRANT READ,WRITE ON DIRECTORY dpump_dir1 TO scott;

Note that READ or WRITE permission to a directory object means only that the Oracle

database will read or write that file on your behalf. You are not given direct access to those

files outside of the Oracle database unless you have the appropriate operating system

privileges. Similarly, the Oracle database requires permission from the operating system to

read and write files in the directories.

Once the directory access is granted, the user scott can export his database objects with

command arguments:

3. >expdp username/password DIRECTORY=dpump_dir1

dumpfile=scott.dmp

Comparison of command-line parameters from Original Export and Import to Data Pump

Data Pump commands have a similar look and feel to the original Export and Import

commands, but are different. 

Below are a few examples that demonstrate some of these differences.

1) Example import of tables from scott’s account to jim’s account

Original Import:

> imp username/password FILE=scott.dmp FROMUSER=scott TOUSER=jim TABLES=(*)

Data Pump Import:

> impdp username/password DIRECTORY=dpump_dir1 DUMPFILE=scott.dmp

TABLES=scott.emp REMAP_SCHEMA=scott:jim

Note how the FROMUSER/TOUSER syntax is replaced by the REMAP_SCHEMA option.

2) Example export of an entire database to a dump file with all GRANTS,INDEXES, and data

> exp username/password FULL=y FILE=dba.dmp GRANTS=y INDEXES=y ROWS=y

> expdp username/password FULL=y INCLUDE=GRANT INCLUDE= INDEX

DIRECTORY=dpump_dir1 DUMPFILE=dba.dmp CONTENT=ALL

Data Pump offers much greater metadata filtering than original Export and Import. The INCLUDE

parameter allows you to specify which object (and its dependent objects) you want to keep in the

export job. The EXCLUDE parameter allows you to specify which object (and its dependent

objects) you want to keep out of the export job. You cannot mix the two parameters in one job.

Both parameters work with Data Pump Import as well, and you can use different INCLUDE and

EXCLUDE options for different operations on the same dump file.

3) Tuning Parameters

Unlike original Export and Import, which used the BUFFER, COMMIT, COMPRESS,

CONSISTENT, DIRECT, and RECORDLENGTH parameters, Data Pump needs no tuning

to achieve maximum performance. Data Pump chooses the best method to ensure that data

and metadata are exported and imported in the most efficient manner. Initialization parameters

should be sufficient upon installation.

4) Moving data between versions

The Data Pump method for moving data between different database versions is different from

the method used by original Export and Import. With original Export, you had to run an

older version of Export to produce a dump file that was compatible with an older database

version. With Data Pump, you use the current Export version and simply use the VERSION

parameter to specify the target database version. You cannot specify versions earlier than

Oracle Database 10g (since Data Pump did not exist before 10g).

Example:

> expdp username/password TABLES=hr.employees VERSION=10.1

DIRECTORY=dpump_dir1 DUMPFILE=emp.dmp

Data Pump Import can always read dump file sets created by older versions of Data Pump

Export.

Note that Data Pump Import cannot read dump files produced by original Export.

Maximizing the Power of Oracle Data Pump

Data Pump works great with default parameters, but once you are comfortable with Data

Pump, there are new capabilities that you will want to explore.

Parallelism

Data Pump Export and Import operations are processed in the database as a Data Pump job,

which is much more efficient that the client-side execution of original Export and Import.

Now Data Pump operations can take advantage of the server’s parallel processes to read or

write multiple data streams simultaneously (PARALLEL is only available in the Enterprise

Edition of Oracle Database.)

The number of parallel processes can be changed on the fly using Data Pump’s interactive

command-line mode. You may have a certain number of processes running during the day

and decide to change that number if more system resources become available at night (or vice

versa).

For best performance, you should do the following:

• Make sure your system is well balanced across CPU, memory, and I/O.

• Have at least one dump file for each degree of parallelism. If there aren’t enough dump

files, performance will not be optimal because multiple threads of execution will be trying

to access the same dump file.

• Put files that are members of a dump file set on separate disks so that they will be written

and read in parallel.

• For export operations, use the %U variable in the DUMPFILE parameter so multiple dump

files can be automatically generated.

Example:

> expdp username/password DIRECTORY=dpump_dir1 JOB_NAME=hr

DUMPFILE=par_exp%u.dmp PARALLEL=4 REMAP

Oracle 

• REMAP_TABLESPACE – This allows you to easily import a table into a different

tablespace from which it was originally exported. The databases have to be 10.1 or later.

Example:

> impdp username/password REMAP_TABLESPACE=tbs_1:tbs_6

DIRECTORY=dpumpdir1 DUMPFILE=employees.dmp

• REMAP_DATAFILES – This is a very useful feature when you move databases

between platforms that have different file naming conventions. This parameter changes the

source datafile name to the target datafile name in all SQL statements where the source

datafile is referenced. Because the REMAP_DATAFILE value uses quotation marks, it’s

best to specify the parameter within a parameter file.

Example:

The parameter file, payroll.par, has the following content:

DIRECTORY=dpump_dir1

FULL=Y

DUMPFILE=db_full.dmp

REMAP_DATAFILE=”’C:\DB1\HRDATA\PAYROLL\tbs6.dbf’:’/db1/hrdata/payroll/tbs6.dbf’”

You can then issue the following command:

> impdp username/password PARFILE=payroll.par

Even More Advanced Features of Oracle Data Pump

Beyond the command-line and performance features of Oracle Data Pump are new capabilities

that DBAs will find invaluable. A couple of prominent features are described here.

Interactive Command-Line Mode

You have much more control in monitoring and controlling Data Pump jobs with interactive

command-line mode. Because Data Pump jobs run entirely on the server, you can start an

export or import job, detach from it, and later reconnect to the job to monitor its progress.

Here are some of the things you can do while in this mode.

• See the status of the job. All of the information needed to monitor the job’s execution is

available.

• Add more dump files if there is insufficient disk space for an export file.

• Change the default size of the dump files.

• Stop the job (perhaps it is consuming too many resources) and later restart it (when more

resources become available).

• Restart the job. If a job was stopped for any reason (system failure, power outage), you can

attach to the job and then restart it.

• Increase or decrease the number of active worker processes for the job. (Enterprise Edition

only.)

• Attach to a job from a remote site (such as from home) to monitor status.

Network Mode

Data Pump gives you the ability to pass data between two databases over a network (via a

database link), without creating a dump file on disk. This is very useful if you’re moving

data between databases, like data marts to data warehouses, and disk space is not readily

available. Note that if you are moving large volumes of data, Network mode is probably

going to be slower than file mode.

Network export creates the dump file set on the instance where the Data Pump job is running

and extracts the metadata and data from the remote instance.

Network export gives you the ability to export read-only databases. (Data Pump Export

cannot run locally on a read-only instance because the job requires write operations on the

instance.) 

This is useful when there is a need to export data from a standby database.

Generating SQLFILES

In original Import, the INDEXFILE parameter generated a text file which contained the SQL

commands necessary to recreate tables and indexes that you could then edit to get a workable

DDL script.

With Data Pump, it’s a lot easier to get a workable DDL script. When you run Data Pump

Import and specify the SQLFILE parameter, a text file is generated that has the necessary

DDL (Data Definition Language) in it to recreate all object types, not just tables and indexes.

Although this output file is ready for execution, the DDL statements are not actually

executed, so the target system will not be changed.

SQLFILEs can be particularly useful when pre-creating tables and objects in a new

database. Note that the INCLUDE and EXCLUDE parameters can be used for tailoring

sqlfile output. For example, if you want to create a database that contains all the tables

and indexes of the source database, but that does not include the same constraints, grants,

and other metadata, you would issue a command as follows:

>impdp username/password DIRECTORY=dpumpdir1 DUMPFILE=expfull.dmp

SQLFILE=dpump_dir2:expfull.sql INCLUDE=TABLE,INDEX

The SQL file named expfull.sql is written to dpump_dir2 and would include SQL DDL that

could be executed in another database to create the tables and indexes as desired.