Wednesday, February 19, 2014

Basic ETL Testing Interview Questions - Part 1

Hi Guys, Hope you all are doing well. I have come up with my new post on ETL / Data Warehouse testing questions which I came across during my interview with various companies. I believe that this blog will be helpful to experience candidate in interview. These interview questions are mostly straight forward. I will come up with more tricky questions later. Please post your comments and suggestions ,which will make learning better for all. I am not posting the answer here, if required I will post it later. Please let me know if you like the post, so you can see more post on ETL.. 

Keep Sharing,Keep Learning guys :)

21 Basic ETL Testing Interview Questions and Answers: 1. What's the different between OLTP and OLAP system? Please provide one example for both. ================================================================================ 2. What's the advantage with Snowflake compared to Star Schema? ================================================================================ 3. What is dimensional modelling? ================================================================================ 4.Let's suppose you are working on a tech refresh project i.e. (from VB code to .net code). Which type of testing you will be doing in this project ?? ================================================================================ 5.Why OLAP system are not normalized while OLTP are highly normalized system? ================================================================================ 6. Which SCD type is used to store all historical data along with current data? ================================================================================ 7.What's the difference between active and passive transformation? ================================================================================ 8. How ETL testing is different from conventional testing? ================================================================================ 9. What do you understand by ETL ? Why we need ETL ? ================================================================================ 10. What is the difference between data mart and data warehouse? ================================================================================ 11. What are the different architectures of data warehouse systems? ================================================================================ 12. Let's suppose in a test scenario one column is added in a table. What kind of test cases you will write? ================================================================================ 13. If a requirement keeps changing, then how will you test? 14. What do you understand by business process testing ? ================================================================================ 15. Which are the important steps carried out in ETL after extracting the data from source system and before transforming the data?? ================================================================================ 16. What do you understand by fact and dimension table? ================================================================================ 17. What do you understand by slowly changing dimensions? ================================================================================ 18. How would you validate that junk data is not loaded into the target table ? ================================================================================ 19. How do you check the logs if any workflow (Informatica) failed while executing? ================================================================================ 20. Have you worked on Multi file systems? How ab-initio graph process those files?? ================================================================================ 21. Let's suppose we are migrating the data from legacy file system to oracle database tables. How would you validate that the data is migrated properly? Tell me the test scenario and test cases you will write to test this requirement. ??
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15 comments:

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  4. Hi team, these are very generous questions.. It will be really helpful if we reply answers by realtime guys with examples of challenges faced in Etl..

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  12. Exercise 1: Please describe the test cases needed in the following scenario:
    Dimension tables: All data is loaded initially and then incremental loads every day for new/updated records
    Fact table: Data loaded incrementally every day


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