Informatica ETL Interview Questions and Answers – Part 2

Informatica Interview Questions & Answers:

H. How to join 2 tables, without using any condition?

  • It is not possible to actually possible to join two tables without using any condition. If we would like to join two tables, then in source qualifier transformation add all the ports from two tables(if both tables are from same database source) and write down your join condition in user defined join option or otherwise write down join condition inside the sql query option with generated sql query.
  • OR simply use a dummy condition like 1=1.

I. Can we return two columns from an unconnected lookup?

  • Yes. Concatenate two columns. However return port will be one.

J. I have an aggregater in my mapping and no group by port on
any column and I am passing 100 rows through aggregater, so how many rows I will get as output from aggregater?

  • Last row only.

K. What is the diff between union, joiner and lookup?

  • Union – Can join two tables without common port.
  • Joiner– Can join any two heterogeneous sources, but common port is necessary.
  • Lookup – We can join two tables by using sql over-ride, apart from that we can check whether the row is already existing or not.

L. What are the similarities/differences between ROUTER and FILTER?

  • Similarity between Router and Filter is that both transformation would be able to discard data based on some filter condition.
  • The Differences are… 1.Using router transformation one would able to test incoming data for multiple filter condition and if none of the condition met the incoming rows gets rerouted to DEFAULT group.
  • 2.Using filter transformation, one would be able to pass data to next transformation based on single filter pipeline condition. There is no option of routing data that doesn’t match the condition like ROUTER Transformation.

M. What is a complex mapping?

A complex mapping  generally will have the following characteristics:

  • Difficult requirement
  • More no.of transformations
  • Having difficult business logic
  • May require combination of two or more methods/combinations
  • Complex business logic
  • More than 30 unconnected lookup

N. Flat file contains n number of records, we have to load the records in target from 51 to 100. How to do that in Informatica?

  • Use sequence generator to get row no. for each record, then use filter giving the condition(row no. greater than 50 and less than 100)

O. What are the limitations for using target load type “Bulk” in the session?

  • Update strategy
  • Less number of records
  • Target should be relational DB
  • No constraints in the target table

 

Next ⇒ Informatica Interview Questions Continued …Page 3

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