Datapump Export handy examples: Analytical backup of your data

Here I want to show some handy examples, how to run the datapump export.

When we do conventional backup of our database either by using RMAN or by using hot or cold backup methods then output file (backup file) actually contains block to block copy of source file. Now these files used to restore the data then following two condition must be followed up:

• Platform must not be changed.
• Backup process should identify the oracle blocks from backup files.

Interestingly, if we have dump export then it can be used as analytical backup. It means....... it can imported irrespective platform and oracle database.

Let us have some examples how to perform the export from database:

Performing a Table-Mode Export

Issue the following Data Pump export command to perform a table export of the tables employees and jobs from the human resources (hr) schema:

expdp hr/hr TABLES=employees,jobs DUMPFILE=dpump_dir1:table.dmp NOLOGFILE=y
Because user hr is exporting tables in his own schema, it is not necessary to specify the schema name for the tables. The NOLOGFILE=y parameter indicates that an Export log file of the operation will not be generated.

Data-Only Unload of Selected Tables and Rows

the contents of a parameter file (exp.par) that you could use to perform a data-only unload of all tables in the human resources (hr) schema except for the tables countries and regions. Rows in the employees table are unloaded that have a department_id other than 50. The rows are ordered by employee_id.

Only Unload of Selected Tables and Rows

DIRECTORY=dpump_dir1
DUMPFILE=dataonly.dmp
CONTENT=DATA_ONLY
EXCLUDE=TABLE:"IN ('COUNTRIES', 'REGIONS')"
QUERY=employees:"WHERE department_id !=50 ORDER BY employee_id"

You can issue the following command to execute the exp.par parameter file:

> expdp hr/hr PARFILE=exp.par

Estimating Disk Space Needed in a Table-Mode Export

the use of the ESTIMATE_ONLY parameter to estimate the space that would be consumed in a table-mode export, without actually performing the export operation. Issue the following command to use the BLOCKS method to estimate the number of bytes required to export the data in the following three tables located in the human resource (hr) schema: employees, departments, and locations.

Example 2-3 Estimating Disk Space Needed in a Table-Mode Export

> expdp hr/hr DIRECTORY=dpump_dir1 ESTIMATE_ONLY=y TABLES=employees,
departments, locations LOGFILE=estimate.log

Performing a Schema-Mode Export

The estimate is printed in the log file and displayed on the client's standard output device. The estimate is for table row data only; it does not include metadata.

A schema-mode export (the default mode) is performed, but the CONTENT parameter effectively limits the export to an unload of just the table's data. The DBA previously created the directory object dpump_dir1 which points to the directory on the server where user hr is authorized to read and write export dump files. The dump file dataonly.dmp is created in dpump_dir1.

> expdp hr/hr DUMPFILE=dpump_dir1:expschema.dmp LOGFILE=dpump_dir1:expschema.log

Performing a Parallel Full Database Export

> expdp hr/hr FULL=y DUMPFILE=dpump_dir1:full1%U.dmp, dpump_dir2:full2%U.dmp
FILESIZE=2G PARALLEL=3 LOGFILE=dpump_dir1:expfull.log JOB_NAME=expfull

Because this is a full database export, all data and metadata in the database will be exported. Dump files full101.dmp, full201.dmp, full102.dmp, and so on will be created in a round-robin fashion in the directories pointed to by the dpump_dir1 and dpump_dir2 directory objects. For best performance, these should be on separate I/O channels. Each file will be up to 2 gigabytes in size, as necessary. Initially, up to three files will be created. More files will be created, if needed. The job and master table will have a name of expfull. The log file will be written to expfull.log in the dpump_dir1 directory.

Using Interactive Mode to Stop and Reattach to a Job

While the export is running, press Ctrl+C. This will start the interactive-command interface of Data Pump Export. In the interactive interface, logging to the terminal stops and the Export prompt is displayed.
Stopping and Reattaching to a Job

At the Export prompt, issue the following command to stop the job:

Export> STOP_JOB=IMMEDIATE
Are you sure you wish to stop this job ([y]/n): y

The job is placed in a stopped state and exits the client.

Enter the following command to reattach to the job you just stopped:

> expdp hr/hr ATTACH=EXPFULL

After the job status is displayed, you can issue the CONTINUE_CLIENT command to resume logging mode and restart the expfull job.

Export> CONTINUE_CLIENT

A message is displayed that the job has been reopened, and processing status is output to the client.

Mapping between the parameters of datapump export and original export

some of the parameter names may be the same, but the functionality is slightly different.

Original Export Parameter	Comparable Data Pump Export Parameter
BUFFER	A parameter comparable to BUFFER is not needed.
COMPRESS	A parameter comparable to COMPRESS is not needed.
CONSISTENT	A parameter comparable to CONSISTENT is not needed. Use FLASHBACK_SCN and FLASHBACK_TIME for this functionality.
CONSTRAINTS	EXCLUDE=CONSTRAINT
DIRECT	A parameter comparable to DIRECT is not needed. Data Pump Export automatically chooses the best method (direct path mode or external tables mode).
FEEDBACK	STATUS
FILE	DUMPFILE
FILESIZE	FILESIZE
FLASHBACK_SCN	FLASHBACK_SCN
FLASHBACK_TIME	FLASHBACK_TIME
FULL	FULL
GRANTS	EXCLUDE=GRANT
HELP	HELP
INDEXES	EXCLUDE=INDEX
LOG	LOGFILE
OBJECT_CONSISTENT	A parameter comparable to OBJECT_CONSISTENT is not needed.
OWNER	SCHEMAS
PARFILE	PARFILE
QUERY	QUERY
RECORDLENGTH	A parameter comparable to RECORDLENGTH is not needed because sizing is done automatically.
RESUMABLE	A parameter comparable to RESUMABLE is not needed. This functionality is automatically provided for privileged users.
RESUMABLE_NAME	A parameter comparable to RESUMABLE_NAME is not needed. This functionality is automatically provided for privileged users.
RESUMABLE_TIMEOUT	A parameter comparable to RESUMABLE_TIMEOUT is not needed. This functionality is automatically provided for privileged users.
ROWS=N	CONTENT=METADATA_ONLY
ROWS=Y	CONTENT=ALL
STATISTICS	A parameter comparable to STATISTICS is not needed. Statistics are always saved for tables.
TABLES	TABLES
TABLESPACES	TABLESPACES (Same parameter; slightly different behavior)
TRANSPORT_TABLESPACE	TRANSPORT_TABLESPACES (Same parameter; slightly different behavior)
TRIGGERS	EXCLUDE=TRIGGER
TTS_FULL_CHECK	TRANSPORT_FULL_CHECK
USERID	A parameter comparable to USERID is not needed. This information is supplied as the username/password when you invoke Export.
VOLSIZE	A parameter comparable to VOLSIZE is not needed.

This table does not list all Data Pump Export command-line parameters.

Original Export and Import Versus Data Pump Export and Import

it is important to understand that many of the concepts behind them do not apply to Data Pump Export (expdp) and Data Pump Import (impdp). In particular:

• Data Pump Export and Import operate on a group of files called a dump file set rather than on a single sequential dump file.

• Data Pump Export and Import access files on the server rather than on the client. This results in improved performance. It also means that directory objects are required when you specify file locations.

• The Data Pump Export and Import modes operate symmetrically, whereas original export and import did not always exhibit this behavior.

  For example, suppose you perform an export with FULL=Y, followed by an import using SCHEMAS=HR. This will produce the same results as if you performed an export with SCHEMAS=HR, followed by an import with FULL=Y.

• Data Pump Export and Import use parallel execution rather than a single stream of execution, for improved performance. This means that the order of data within dump file sets and the information in the log files is more variable.

• Data Pump Export and Import represent metadata in the dump file set as XML documents rather than as DDL commands. This provides improved flexibility for transforming the metadata at import time.

• Data Pump Export and Import are self-tuning utilities. Tuning parameters that were used in original Export and Import, such as BUFFER and RECORDLENGTH, are neither required nor supported by Data Pump Export and Import.

• At import time there is no option to perform interim commits during the restoration of a partition. This was provided by the COMMIT parameter in original Import.

• There is no option to merge extents when you re-create tables. In original Import, this was provided by the COMPRESS parameter. Instead, extents are reallocated according to storage parameters for the target table.

• Sequential media, such as tapes and pipes, are not supported.

• The Data Pump method for moving data between different database versions is different than the method used by original Export/Import. With original Export, you had to run an older version of Export (exp) to produce a dump file that was compatible with an older database version. With Data Pump, you can use the current Export (expdp) version and simply use the VERSION parameter to specify the target database version.
  

• When you are importing data into an existing table using either APPEND or TRUNCATE, if any row violates an active constraint, the load is discontinued and no data is loaded. This is different from original Import, which logs any rows that are in violation and continues with the load.

• Data Pump Export and Import consume more undo tablespace than original Export and Import. This is due to additional metadata queries during export and some relatively long-running master table queries during import. As a result, for databases with large amounts of metadata, you may receive an ORA-01555: snapshot too old error. To avoid this, consider adding additional undo tablespace or increasing the value of the UNDO_RETENTION initialization parameter for the database.

• If a table has compression enabled, Data Pump Import attempts to compress the data being loaded. Whereas, the original Import utility loaded data in such a way that if a even table had compression enabled, the data was not compressed upon import.

• Data Pump supports character set conversion for both direct path and external tables. Most of the restrictions that exist for character set conversions in the original Import utility do not apply to Data Pump. The one case in which character set conversions are not supported under the Data Pump is when using transportable tablespaces.

DataPump Export and Import: New features

It is introduced with following new features:

• The ability to specify the maximum number of threads of active execution operating on behalf of the Data Pump job.
• The ability to restart Data Pump jobs.
• The ability to detach from and reattach to long-running jobs without affecting the job itself. This allows DBAs and other operations personnel to monitor jobs from multiple locations. The Data Pump Export and Import utilities can be attached to only one job at a time; however, you can have multiple clients or jobs running at one time.
• Support for export and import operations over the network, in which the source of each operation is a remote instance.
• The ability, in an import job, to change the name of the source datafile to a different name in all DDL statements where the source datafile is referenced.
• Enhanced support for remapping tablespaces during an import operation.
• Support for filtering the metadata that is exported and imported, based upon objects and object types.
• Support for an interactive-command mode that allows monitoring of and interaction with ongoing jobs.
• The ability to estimate how much space an export job would consume, without actually performing the export.
• The ability to specify the version of database objects to be moved. In export jobs, VERSION
• Most Data Pump export and import operations occur on the Oracle database server instead of clients.

Introducing:

Oracle Database 10g have introduced new feature Datapump to more enhance export and import process in database. It will replace the use of exp and imp utility from older versions. Also there is no migration support given from conventional export-import to Datapump export-import.

In this I am going to explore Datapump export-import utility and comparing-contrasting with conventional export-import.