Data warehouse Latest Interview Questions and Answers Part-3
An active datawarehouse is a datawarehouse that enables decision makers within a company or organization to manage customer relationships effectively and efficiently.
22. What is the difference between Datawarehouse and OLAP?
Datawarehouse is a place where the whole data is stored for analyzing, but OLAP is used for analyzing the data, managing aggregations, information partitioning into minor level information.
23. What is ER Diagram?
ER diagram is abbreviated as Entity-Relationship diagram which illustrates the interrelationships between the entities in the database. This diagram shows the structure of each tables and the links between the tables.
24. What are the key columns in Fact and dimension tables?
Foreign keys of dimension tables are primary keys of entity tables. Foreign keys of fact tables are the primary keys of the dimension tables.
25. What is SCD?
SCD is defined as slowly changing dimensions, and it applies to the cases where record changes over time.
26. What are the types of SCD?
There are three types of SCD and they are as follows:
SCD 1 – The new record replaces the original record
SCD 2 – A new record is added to the existing customer dimension table
SCD 3 – A original data is modified to include new data
27. What is BUS Schema?
BUS schema consists of suite of confirmed dimension and standardized definition if there is a fact tables.
28. What is Star Schema?
Star schema is nothing but a type of organizing the tables in such a way that result can be retrieved from the database quickly in the data warehouse environment.
29. What is Snowflake Schema?
Snowflake schema which has primary dimension table to which one or more dimensions can be joined. The primary dimension table is the only table that can be joined with the fact table.
30. What is a core dimension?
Core dimension is nothing but a Dimension table which is used as dedicated for single fact table or datamart.