Data Warehousing Interview Questions

1. What is a data-warehouse?

2. What are Data Marts?

4. What is ER Diagram?

5. What is a Star Schema?

6. What is Dimensional Modeling?

7. What Snow Flake Schema?

8. What are the Different methods of loading Dimension tables?

9. What are Aggregate tables?

10. What is the Difference between OLTP and OLAP?

11. What is ETL?

12. What are the various ETL tools in the Market?

13. What are the various Reporting tools in the Market?

14. What is Fact table?

15. What is a dimension table?

16. What is a lookup table?

17. What is a general purpose scheduling tool? Name some of them?

18. What are modeling tools available in the Market? Name some of them?

19. What is real time data-warehousing?

20. What is data mining?

21. What is Normalization? First Normal Form, Second Normal Form, Third Normal Form?

22. What is ODS?

23. What type of Indexing mechanism do we need to use for a typical data warehouse?

24. Which columns go to the fact table and which columns go the dimension table?

     (My user needs to see <data element> <data element> broken by

     <data element> <data element>

     All elements before broken = Fact Measures

     All elements after broken =    Dimension Elements

25. What is a level of Granularity of a fact table? What does this signify?

     (Weekly level summarization there is no need to have Invoice Number in the fact table anymore)

26. How are the Dimension tables designed?

     De-Normalized , Wide, Short , Use Surrogate Keys, Contain Additional date fields and flags.

27. What are slowly changing dimensions?

28. What are non-additive facts? (Inventory, Account balances in bank)

29. What are conformed dimensions?

30. What is VLDB? (Database is too large to back up in a time frame then it's a VLDB)

31. What are SCD1, SCD2, and SCD3?


Few more questions.......



1. What are the different Dimensional modeling Techniques are Available?
2. What is the Difference between Star-schema and snow-flake-schema? When we go
for star and snow-flake?
3. What are the types of dimension and facts are in DW?
4. What is the life cycle of Data warehousing project?
5. What is a Data-model?
6. What is the Difference between Top-down Approach and Bottom-up Approach?
7. What is a factless-fact Table?
8. What is a confirmed-dimension?
9. What is a junk-dimension?
10. What is a cleansing?
11. Tell me about your current project?
12. What is your role or job profile in the project?
13. What is your Job profile?
14. What is dimesion and fact?
15. What are types of dimensions?
16. What are confirmed dimensions?
17. What are generated dimensions?
18. What are slowly changing dimensions?
19. How many data marts in your project?
20. What is data mart name in your project?
21. What is the size of your data mart?
22. What is factless fact table? Give example.
23. How many fact tables are used in the project?
24. What is your fact table name in your project?
25. How many dimension tables used in the project?
26. What are the names of the dimension tables?
27. What is Schema? Types? Explain Star-Schema and Snowflake Schema with difference.
Which schema you used in your project? Why?
28. Why star-schema called as star-schema? Give example.
29. How frequently and from where you get the data as source?
30. What is difference between data mart and data warehouse?
31. What is composite key?
32. What is surrogate key? When you will go for it?
33. What is dimensional modeling?
34. What are SCD and SGT? Difference between them? Example of SGT from your project.
35. How do you rate yourself in data warehouse?
36. What is the status of your current project?
37. What is data warehouse?
38. What is ‘Star-Schema’?
39. What is ‘Snowflake-Schema’?
40. What is difference between Star-Schema and Snowflake-Schema?
41. What is mean by surrogate key?
42. What is ‘Conformed Dimension’?
43. What is Factless Fact Table?
44. When will we use connected and unconnected lookup?
45. Which cache supports connected and unconnected lookup?
46. What is the difference between SCD Type2 and SCD Type3?
47. Draw the ETL Architecture?
48. Draw the DWH Architecture?

Few more Here
You can find answers for all these questions in this blog itself.