DATAPUMP IN ORACLE

For using DATAPUMP through DB CONSOLE

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.

    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:

    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:

    >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

• 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.