Monday, 9 February 2015

Latest Oracle ETL Interview Questions and Answers

Below are some important Oracle ETL interview questions which are asked in most MNC company interviews for beginners or professionals.

21. What is Full load & Incremental or Refresh load?
Full Load: completely erasing the contents of one or more tables and reloading with fresh data.
Incremental Load: applying ongoing changes to one or more tables based on a predefined schedule.

22. How to determine what records to extract?
When addressing a table some dimension key must reflect the need for a record to get extracted. Mostly it will be from time dimension (e.g. date >= 1st of current mth) or a transaction flag (e.g. Order Invoiced Stat). Foolproof would be adding an archive flag to record which gets reset when record changes.

23. Do we need an ETL tool? When do we go for the tools in the market?
ETL Tool:
It is used to Extract(E) data from multiple source systems(like RDBMS,Flat files,Mainframes,SAP,XML etc) transform(T) them based on Business requirements and Load(L) in target locations.(like tables,files etc).
Need of ETL Tool:
An ETL tool is typically required when data scattered accross different systems.(like RDBMS,Flat files,Mainframes,SAP,XML etc).

24. Can we use procedural logic inside Infromatica? If yes how, if now how can we use external procedural logic in informatica?
Yes, you can use advanced external transformation. for more detail you can refer the manual of informatica transformation guide in that advance external transformation. You can use c++ language on unix and c++, vb vc++ on windows server.

25. Can we override a native sql query within Informatica? Where do we do it? How do we do it?
Yes,we can override a native sql query in source qualifier and lookup transformation.
In lookup transformation we can find "Sql override" in lookup using this option we can do this.

26. What are parameter files? Where do we use them?
Parameter file defines the value for parameter and variable used in a workflow, worklet or session.

27. How can we use mapping variables in Informatica? Where do we use them?
Yes. we can use mapping variable in Informatica.
The Informatica server saves the value of mapping variable to the repository at the end of session run and uses that value next time we run the session.

28. What is a mapping, session, worklet, workflow, mapplet?
A mapping represents dataflow from sources to targets.
A mapplet creates or configures a set of transformations.
A workflow is a set of instruction sthat tell the Informatica server how to execute the tasks.
A worklet is an object that represents a set of tasks.
A session is a set of instructions that describe how and when to move data from sources to targets.

29. What is Informatica Metadata and where is it stored?
Informatica Metadata is data about data which stores in Informatica repositories.

30. How do we call shell scripts from informatica?
Specify the Full path of the Shell script the "Post session properties of session/workflow".
More Questions & Answers :-
Page1  Page2  Page3  Page4

No comments:

Post a Comment