Tuesday, 3 February 2015

etl interview questions and answers for freshers (Part3)

21. Which transformation should we use to normalize the COBOL and relational sources?
Normalizer Transformation.

22. What is the use of tracing levels in transformation?
Tracing levels store information about mapping and transformations.

23. What are the basic needs to join two sources in a source qualifier?
Two sources should have primary and foreign key relationships. Two sources should have matching data types.

24. What is update strategy transformation?
This transformation is used to maintain the history data or just most recent changes in to target table.

25. Describe two levels in which update strategy transformation sets?
Within a session. When you configure a session, you can instruct the Informatica Server to either treat all records in the same way (for example, treat all records as inserts), or use instructions coded into the session mapping to flag records for different database operations. Within a mapping. Within a mapping, you use the Update Strategy transformation to flag records for insert, delete, update, or reject.

26. What are the various types of transformation?
Various types of transformation are: Aggregator Transformation, Expression Transformation, Filter Transformation, Joiner Transformation, Lookup
Transformation, Normalizer Transformation, Rank Transformation, Router Transformation, Sequence Generator Transformation, Stored Procedure Transformation,
Sorter Transformation, Update Strategy Transformation, XML Source Qualifier Transformation, Advanced External Procedure Transformation, External Transformation.

27. What is the difference between active transformation and passive transformation?
An active transformation can change the number of rows that pass through it, but a passive transformation can not change the number of rows that pass through it.

28. What is the use of control break statements?
They execute a set of codes within the loop and endloop.

29. What is the difference between static cache and dynamic cache?
In case of dynamic cache, when we are inserting a new row it checks the lookup cache to see if it exists, if not inserts it into the target as well as
the cache but in case of static cache the new row is written only in the target and not the lookup cache.
The lookup cache remains static and does not change during the session but incase of dynamic cache the server inserts, updates in the cache during session.

30. How do we join two tables without joiner or SQL override?
We can join the tables using lookup tansformation and making a cartesian product.
More Questions & Answers :-
Part1  Part2  Part3  Part4  Part5

No comments:

Post a Comment