Top Data Warehouse Interview Questions to Ace Your Next Job

Data warehousing is important in managing large amounts of data to ensure business decisions are based on appropriate data. As data warehouses are highly important in current data-centric companies, there is a need for people who can handle data modelling, ETL processes, database management, etc. In this article, you will find frequently asked data warehouse interview questions for beginners and for those who have already gathered some experience.

Data Warehouse: Overview

Data warehouse concepts are a centralised repository in which massive, structured data from numerous sources will be kept and easily queryable, reportable, and analyseable. It integrates averaged information from various databases and systems and standardizes it to serve as an even more useful tool for deciding with reflections on key data. Data warehouses fundamentally differ from other enterprise databases, including online transaction processing systems designed to process transactions and not analytical queries.

Data Warehouse Interview Question for Freshers

Here, we will focus on some questions which are frequently asked of the freshers:

1. What is an aggregate table in a Data warehouse?

An aggregate table is a table which contains data stored in an existing OLAP warehouse and groups it to a certain level of dimensions. It always takes less time and effort to query data from the aggregated table rather than from a table with more records than the aggregated table.

2. What do you understand about metadata in a data warehouse?

Metadata is information about information. Data types, field ordering, the amount of columns used, and fixed and limited widths are all included in the metadata.

3. Define the ER diagram in data warehousing.

An entity-relationship diagram, or ER diagram, is a framework that shows how various entities in a database interact with one another. Every table is represented in the diagram, along with every relationship between them.

4. What do you understand by Star Schema?

Star Schema organises the table so that the data warehousing platform can easily access the results.

5. What do you mean by SCD?

A slowly changing dimension, or SCD for short, stores and handles historical data. It is one of the most important functions that facilitate tracking dimension record history.

6. What are the functions of a warehouse manager?

A warehouse manager must do referential integrity and consistency tests across the underlying data to provide business views, indexes, and partition views. After its captured life, the data is preserved and backed up in the data warehouse, and the source data is combined and converted into temporary storage.

 7. What do you understand by ODS?

A database created for data integration and further actions on data from many sources is known as an ODS (Operational Data Store). A real-time operational data repository is returned to the operating system without any data. It can be sent to the Data Warehouse for reporting.

8. What does "dimensional modelling" mean?

Modelling is the focus of data warehousing. It is the conceptual organization of data into storage. It discusses data objects and their relationship to the software's rules for managing other data. The data warehouse also allows for multidimensional modelling.

9. List the three main purposes of dimensions.

The following are the dimensions' main purposes:

• Filtering: It selects a more manageable portion of our data set for examination. Usually, it is transient.

• Labelling: labelling is the process of tagging a collection of samples. It enables querying of data.

• Grouping: Classifying data into small buckets is known as grouping.

10. What are the duties of the query manager?

The query manager controls all user queries and actions. End-user access is used to define and analyse the query manager's complexity. End-user access determines how anger is defined and assessed. To extract data, the query manager oversees all user-generated queries within the environment.

Conclusion

Mastering Data warehouse concepts and understanding key data warehouse interview questions are essential for anyone aspiring to excel in this field. Data warehouses have a significant role in business intelligence: they allow organisations to draw out data, analyse it, and use it for their decision-making process. They range from understanding basic concepts, such as star schema and dimensional modelling metadata, to complex ETL processes and operational data store queries.