Monday, April 11, 2011

Question On Oracle Data Pump

Here are some question related to Data Pump which will help you to clear your doubt regarding Data Pump.

1.) What is Oracle Data Pump?
Oracle Data Pump is a new feature of Oracle  Database 10g  that provides  high speed, parallel,bulk data and metadata movement of Oracle database contents. A new public interface package, DBMS_DATAPUMP, provides a server-side infrastructure for fast data and metadata movement. In Oracle Database 10g, new Export (expdp) and Import (impdp) clients that use this interface have been provided. Oracle recommends that customers use these new Data Pump Export and  Import clients rather than the Original Export and Import clients, since the new utilities have vastly improved performance and greatly enhanced functionality.

2.)  Is Data Pump a feature or an option of Oracle 10g?
Data Pump is a fully integrated feature of Oracle Database 10g. Data Pump is installed automatically during database creation and database upgrade.

3.) What platforms is Data Pump provided on?
Data Pump is available on the Oracle Database 10g Standard Edition, Enterprise Edition, and Personal Edition. However, the  parallel capability  is only available on  Oracle10g   Enterprise Edition. Data Pump is  included on all the same platforms  supported  by Oracle 10g, including Unix, Linux, Windows NT, Windows 2000, and Windows XP.

4.) What are the system requirements for Data Pump?
The  Data  Pump  system requirements  are  the same  as  the  standard Oracle  Database 10g requirements. Data Pump doesn’t need a lot of additional system or database resources, but the time to extract and treat the information will be dependent on the CPU and memory available on each  machine. If  system  resource  consumption becomes  an issue  while a Data Pump job is executing,  the  job  can be  dynamically  throttled to  reduce the number  of  execution  threads.

5.) What is the performance gain of Data Pump Export versus Original Export?
Using  the  Direct  Path  method  of  unloading, a single  stream  of data  unload is about 2 times faster than  original  Export  because  the Direct  Path API  has been  modified to be  even  more efficient. Depending on the level of parallelism, the level of improvement can be much more.

6.) What is the performance gain of Data Pump Import versus Original Import?
A  single  stream  of data load is 15-45 times  faster  Original  Import. The reason it  is  so much faster  is that Conventional  Import uses only  conventional mode  inserts, whereas  Data Pump Import uses the Direct Path  method  of  loading. As  with Export, the  job can be parallelized for even more improvement.

7.) Does Data Pump require special tuning to attain performance gains?
No, Data Pump requires no special tuning. It runs optimally “out of the box”. Original Export and (especially) Import require careful tuning to achieve optimum results.

8.) Why are directory objects needed?
They are needed to ensure data security and integrity. Otherwise, users would be able to read data that they should not have access to and perform unwarranted operations on the server.

9.) What makes Data Pump faster than original Export and Import?
There are three main reasons that Data Pump is faster than original Export and Import. First,the Direct Path data access method (which permits the server to bypass SQL and go right to the data blocks on disk) has been rewritten to be much more efficient and now supports Data Pump Import and Export. Second, because Data Pump does its processing on the server rather than in the client, much less data has to be moved between client and server. Finally, Data Pump was designed from the ground up to take advantage of modern hardware and operating system architectures in ways that original Export/ and Import cannot. These factors combine to produce significant performance improvements for Data Pump over original Export and Import .

10.) How much faster is Data Pump than the original Export and Import utilities?
For a single stream, Data Pump Export is approximately 2 times faster than original Export and Data Pump Import is approximately 15 to 40 times faster than original Import. Speed can be dramatically improved using the PARALLEL parameter.

11.) Why is Data Pump slower on small jobs?
Data Pump was designed for big jobs with lots of data. Each Data Pump job has a master table that has all the information about the job and is needed for restartability. The overhead of creating this master table makes small jobs take longer, but the speed in processing large amounts of data gives Data Pump a significant advantage in medium and larger jobs.

12.) Are original Export and Import going away?
Original Export is being deprecated with the Oracle Database 11g release. Original Import will always be supported so that dump files from earlier releases (release 5.0 and later) will be able to be imported. Original and Data Pump dump file formats are not compatible.

13.) Are Data Pump dump files and original Export and Import dump files compatible?
No, the dump files are not compatible or interchangeable. If you have original Export dump  files, you must use original Import to load them.

14.) How can I monitor my Data Pump jobs to see what is going on?
In interactive mode, you can get a lot of detail through the STATUS command. In SQL, you can query the following views:
  • *       DBA_DATAPUMP_JOBS - all active Data Pump jobs and the state of each job
  • *       USER_DATAPUMP_JOBS – summary of the user’s active Data Pump jobs
  • *       DBA_DATAPUMP_SESSIONS – all active user sessions that are attached to a Data Pump Job
  • *       V$SESSION_LONGOPS – shows all progress on each active Data Pump job

 15.) Can you adjust the level of parallelism dynamically for more or less resource consumption?
Yes, you can dynamically  throttle the number of threads of execution  throughout the lifetime of the job. There is an interactive command mode where you can adjust the level of parallelism. So, for example, you can start up a job during the day with a PARALLEL=2, and then increase it at night to a higher level.

16.) Can I use gzip with Data Pump?
Because Data Pump uses parallel operations to achieve its high performance, you cannot pipe the output of Data Pump export through gzip. Starting in Oracle Database 11g, the  COMPRESSION parameter can be used to compress a Data Pump dump file as it is being created. The  COMPRESSION parameter is available as part of the Advanced Compression Option for Oracle Database 11g

17.)Does Data Pump support all data types?
Yes, all the Oracle database data types are supported via Data Pump’s two data movement mechanisms, Direct Path and External Tables.

18.) What kind of object selection capability is available with Data Pump?
With  Data Pump, there  is  much  more  flexibility  in  selecting  objects  for  unload  and  load operations . You can now unload any subset of database objects  (such as functions, packages, and procedures) and  reload them  on the target platform. Almost  all database object   types can  be excluded or  included in an  operation using  the new  Exclude and Include parameters.

19.) Is it necessary to use the Command line interface or is there a GUI that you can use?
You can either use the Command line interface or the Oracle Enterprise Manager web-based GUI interface.

20.) Can I move a dump file set across platforms, such as from Sun to HP?
Yes, Data Pump handles all the necessary compatibility issues between hardware platforms and operating systems.

21.) Can I take 1 dump file set from my source database and import it into multiple databases?
Yes, a single dump file set can be imported into multiple databases. You can also just import different subsets of the data out of that single dump file set.

22.) Is there a way to estimate the size of an export job before it gets underway?
Yes, you can use the “ESTIMATE ONLY” command to see how much disk space is required for the job’s dump file set before you start the operation.

23.) Can I monitor a Data Pump Export or Import job while the job is in progress?
Yes, jobs can be monitored from any location is going on. Clients may also detach from an executing job without affecting it.

24.) If a job is stopped either voluntarily or involuntarily, can I restart it?
Yes, every Data Pump job creates a Master Table in which the entire record of the job is maintained. The Master Table is the directory to the job, so if a job is stopped for any reason, it can be restarted at a later point in time, without losing any data.

25.) Does Data Pump give me the ability to manipulate the Data Definition Language (DDL)?
Yes, with  Data Pump, it  is  now  possible to change the definition of some  objects  as  they are Created  at  import time. For example, you  can remap  the  source  datafile  name  to the  target datafile name in all DDL statements where the source datafile is referenced. This is really useful if you are moving across platforms with different file system syntax.

26.) Is Network Mode supported on Data Pump?
Yes, Data Pump Export and Import both support a network mode in which the job’s source is a remote oracle instance. This is an overlap of unloading the data, using Export, and loading the data, using Import, so those processes don’t have to be serialized. A database  link  is used for the   network.  You  don’t  have  to worry  about  allocating  file  space  because  there  are  no intermediate dump files.

27.) Does Data Pump support Flashback?
Yes, Data Pump supports the Flashback infrastructure, so you can perform an export and get a dump file set that is consistent with a specified point in time or SCN.

28.) Can I still use Original Export? Do I have to convert to Data Pump Export?
An Oracle9i compatible Export that operates against Oracle Database 10g will ship with Oracle 10g, but   it  does  not export  Oracle Database  10g features. Also, Data Pump Export  has new Syntax   and a new    client executable, so Original  Export  scripts will  need to change.  Oracle recommends that customers convert to use the Oracle Data Pump Export.

29.) How do I import an old dump file into Oracle 10g? Can I use Original Import or do I have to  convert to Data Pump Import?
Original  Import  will be  maintained  and  shipped  forever, so  that  Oracle  Version 5.0  through Oracle9i  dump  files will  be able  to be loaded into Oracle 10g and later. Data Pump Import can only read Oracle Database 11g (and later) Data Pump Export dump files. Data Pump Import has new syntax and a new client executable, so Original Import scripts will need to change.

30.) When would I use SQL*Loader instead of Data Pump Export and Import?
You would use SQL*Loader to load data from external files into tables of an Oracle database.Many customers use SQL*Loader on a daily basis to load files (e.g. financial feeds) into their databases. Data Pump Export and Import may be used less frequently, but for very important tasks, such as migrating between platforms, moving data between development, test, and production databases, logical database backup, and for application deployment throughout a corporation.

31.)When would I use Transportable Tablespaces instead of Data Pump Export and Import?
You would use Transportable Tablespaces when you want to move an entire tablespace of data from one Oracle database to another. Transportable Tablespaces allows Oracle data files to be unplugged from a database, moved or copied to another location, and then plugged into another database. Moving data using Transportable Tablespaces can be much faster than performing either an export or import of the same data, because transporting a tablespace only requires the copying of datafiles and integrating the tablespace dictionary information. Even when transporting a tablespace, Data Pump Export and Import are still used to handle the extraction and recreation of the metadata for that tablespace.

Conclusion
Data Pump is fast and flexible. It replaces original Export and Import starting in Oracle Database 10g.Moving to Data Pump is easy, and opens up a world of new options and features.


Reference : http://www.scribd.com


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