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Oracle ETL Interview Questions

Q   |   QA

ETL tool is ment for extraction data from the legecy systems and load into specified data base with some process of cleansing data.

ex: Informatica,data stage ....etc

OLAP is ment for Reporting purpose.in OLAP data avaliable in Mulitidimectional model. so that u can write smple query to extract data fro the data base.

ex: Businee objects,Cognos....etc 

Informatica allows end users and partners to extend the metadata stored in the repository by associating information with individual objects in the repository. For example, when you create a mapping, you can store your contact information with the mapping. You associate information with repository metadata using metadata extensions.

Informatica Client applications can contain the following types of metadata extensions:

Vendor-defined. Third-party application vendors create vendor-defined metadata extensions. You can view and change the values of vendor-defined metadata extensions, but you cannot create, delete, or redefine them.
User-defined. You create user-defined metadata extensions using PowerCenter/PowerMart. You can create, edit, delete, and view user-defined metadata extensions. You can also change the values of user-defined extensions. 

The best procedure to take a help of debugger where we monitor each and every process of mappings and how data is loading based on conditions breaks. 

There are various ways of Extracting Data from Source Systems.For example , You can use a DATA step, an Import Process .It depends with your input data styles. What kind of File/database it is residing in. Storing ur data in an ODS can be done thru an ODS stmt/export stmt/FILE stmt, again which depends on the file & data format ,You want your output to be in. 

Rejection of records either at the database due to constraint key violation or the informatica server when writing data into target table.These rejected records we can find in the badfiles folder where a reject file will be created for a session.we can check why a record has been rejected.And this bad file contains first column a row indicator and second column a column indicator.
These row indicators or of four types
D-valid data,
O-overflowed data,
N-null data,
T- Truncated data,
And depending on these indicators we can changes to load data successfully to target. 

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