Most Asked Informatica Interview Questions and Answers
Briefly define reusable transformation?
Reusable transformation is used numerous times in mapping. It is different from other mappings which use the transformation since it is stored as a metadata. The transformations will be nullified in the mappings whenever any change in the reusable transformation is made.
What is a mapplet?
A recyclable object that is using mapplet designer is called a mapplet. It permits one to reuse the transformation logic in multitude mappings moreover it also contains set of transformations.
What is the difference between a connected look up and unconnected look up?
When the inputs are taken directly from other transformations in the pipeline it is called connected lookup. While unconnected lookup doesn’t take inputs directly from other transformations, but it can be used in any transformations and can be raised as a function using LKP expression. So it can be said that an unconnected lookup can be called multiple times in mapping.
What do you mean Incremental Aggregation?
Option for incremental aggregation is enabled whenever a session is created for a mapping aggregate. Power center performs incremental aggregation through the mapping and historical cache data to perform new aggregation calculations incrementally.
How Union Transformation is used?
It is a diverse input group transformation which can be used to combine data from different sources. It works like UNION All statement in SQL that is used to combine result set of two SELECT statements.
What is Lookup transformation?
It is used for looking up data in a relational table through mapping. Lookup definition from any relational database is imported from a source which has tendency of connecting client and server. One can use multiple lookup transformation in a mapping.
What is Joiner transformation?
Joiner transformation combines two affiliated heterogeneous sources living in different locations while a source qualifier transformation can combine data emerging from a common source.
What do you mean by filter transformation?
It is a medium of filtering rows in a mapping. Data needs to be transformed through filter transformation and then filter condition is applied. Filter transformation contains all ports of input/output, and the rows which meet the condition can only pass through that filter.
Describe Expression transformation?
Values can be calculated in single row before writing on the target in this form of transformation. It can be used to perform non aggregate calculations. Conditional statements can also be tested before output results go to target tables.
Briefly explain the Aggregator transformation?
It allows one to do aggregate calculations such as sums, averages etc. It is unlike expression transformation in which one can do calculations in groups.
How can you validate all mappings in the repository simultaneously?
All the mappings cannot be validated simultaneously because each time only one mapping can be validated.
Explain the code page compatibility?
When data moves from one code page to another provided that both code pages have the same character sets then data loss cannot occur. All the characteristics of source page must be available in the target page. Moreover if all the characters of source page are not present in the target page then it would be a subset and data loss will definitely occur during transformation due the fact the two code pages are not compatible.
What are the types of metadata that stores in repository?
The types of metadata includes Source definition, Target definition, Mappings, Mapplet, Transformations.
How can repository reports be accessed without SQL or other transformations?
Repository reports are established by metadata reporter. There is no need of SQL or other transformation since it is a web app.
What does role playing dimension mean?
The dimensions that are utilized for playing diversified roles while remaining in the same database domain are called role playing dimensions.