Informatica Interview Tips to Remember
Informatica is a software tool designed to simplify Data Warehouse design and routine tasks related to data transformation and migration i.e. ETL -> Extract, transform and Load. It is a visual interface and you will be dragging and dropping with the mouse in the Designer(client Application).This graphical approach to communicate with all major databases and can move/transform data between them. It can move huge bulk of data in a very effective way.
Here are some of the important Informartica Interview tips to remember :
1. Which transformation should we use to normalize the COBOL and relational sources?
Ans : Normalizer Transformation. When we drag the COBOL source in to the mapping Designer workspace, the normalizer transformation automatically appears, creating input and output ports for every column in the source.
2. Difference between static cache and dynamic cache?
Ans : In case of Dynamic cache when you are inserting a new row it looks at the lookup cache to see if the row existing or not, If not it inserts in the target and cache as well in case of Static cache when you are inserting a new row it checks the cache and writes to the target but not cache
3. What are the join types in joiner transformation?
Ans : Normal Join, Master Join, Detail Join and Outer Join
4. In which conditions we can not use joiner transformation (Limitations of joiner transformation)?
Ans : No restrictions
5. What is the look up transformation?
Ans : Used to look up data in a reational table or view. Lookup is a passive transformation and used to look up data in a flat file or a relational table
6. What are the diffrence between joiner transformation and source qualifier transformation?
Ans : 1. Source Qualifier Operates only with relational sources within the same schema. Joiner can have either heterogeneous sources or relation sources in different schema 2. Source qualifier requires atleast one matching column to perform a join. Joiner joins based on matching port. 3. Additionally, Joiner requires two separate input pipelines and should not have an update strategy or Sequence generator.
1)Joiner can join relational sources which come from different sources whereas in source qualifier the relational sources should come from the same data source. 2)We need matching keys to join two relational sources in source qualifier transformation. Where as we doesn’t need matching keys to join two sources.
7. Why use the lookup transformation?
Ans : Used to look up data in a relational table or view.
8. How can you improve session performance in aggregator transformation?
Ans : By using Incremental Aggregation
9. Can you use the maping parameters or variables created in one maping into any other reusable transformation?
Ans : Yes. Because reusable transformation is not contained with any mapplet or mapping.
10. What is meant by lookup caches?
Ans : Session will read all unique rows from the reference table/ file to fill the local buffer first; then for each row received from up-stream transformation, it tries to match them against the local buffer
11. What is source qualifier transformation?
Ans : SQ is an active transformation. It performs one of the following task: to join data from the same source database to filter the rows when Power centre reads source data to perform an outer join to select only distinct values from the source
12. How the informatica server increases the session performance through partitioning the source?
Ans : Partitioning the session improves the session performance by creating multiple connections to sources and targets and loads data in parallel pipe lines
13. What are the settings that you use to configure the joiner transformation?
Ans : Master group flow detail group flow join condition type of join
14. What are the rank caches?
Ans : The informatica server stores group information in an index catche and row data in data catche
15. What is Code Page Compatibility ?
Ans : When two code pages are compatible, the characters encoded in the two code pages are virtually identical.