Informatica ETL Interview Questions and Answers – Part 1

Informatica Interview Questions & Answers:

A. What are the differences between Connected and Unconnected
lookup?

• Connected lookup participates in the mapping(dataflow), just like any other transformation. Unconnected  lookup is used when a lookup function is used instead in an expression transformation in the mapping in which case the lookup does not appear in the main flow (dataflow) of the mapping. Connected lookup can return more than one value(output port) whereas an Unconnected lookup gives only one output port. Unconnected lookups are reusable.
• Connected transformation is connected to other transformations or directly to target table in the mapping. An unconnected transformation is not connected to other transformations in the mapping. It is called within another transformation, and returns a value to that transformation.

B. When do we use dynamic cache and static cache in connected and unconnected lookup transformations?

• Dynamic cache used for updation of Master Table & SCD(Slowly Changing Dimensions) type 1.
• Static used for Flatfile.

C. What is the tracing level?

• Tracing level means that the amount of data storing in to the log files.
• Tracing Levels are TERSE,VERBOSE,VERBOSE INITIALIZATION and NORMAL.
• This is a kind of explanation when a session log is created….
  • Normal: It explains in a detailed manner
  • Verbose: It explains detailed explanation for each and every row

D. How many types of transformations supported by sorted input?

• Aggregator Transformation,Joiner Transformation and Lookup Transformation support sorted input so that it will increase the session performance.

E. Name 4 output files that Informatica server creates during session running:

• Session log
• Workflow log
• Errors log
• Badfile

F. what is the difference between stop and abort?

• Stop command immediately kills the reading process and doesn’t have any timeout period.
• Abort command gives a time out period of 60 secs to the Informatica server to finish the dtm process else it kills the dtm process.

G. What is Update Override? What are the differences between SQL Override and Update Override?

• Update Override – It is an option available in TARGET instance. By default, Target table is updated based on Primary key values. To update the Target table on non primary key values, we can generate the default Query and override the Query according to the requirement. Suppose for example, if we want to update the record in target table, when a column value=’AAA’ then, we can include this condition in Where clause of default Query.
• Coming to SQL override – It is an option available in Source Qualifier and Lookup transformation where we can include joins, filters, Group by and Order by.

Next⇒ Informatica Interview Questions Continued …Page 2