AI-powered Data Engineer mock interviews

Can you explain the differences between INNER JOIN, LEFT JOIN, and RIGHT JOIN in SQL and provide a scenario where you would use each type of join?

How would you optimize a slow-performing SQL query that involves multiple joins and aggregations? Please provide at least two strategies you would consider for query optimization.

How do you approach designing a star schema for a data warehousing project, and what factors do you consider when deciding on the granularity of the fact table?

Can you explain the concept of slowly changing dimensions and provide an example of when you have implemented Type 2 SCD in a data warehousing project?

Can you explain the difference between full load and incremental load in ETL processes and provide an example of when you would use each approach?

How do you handle data quality issues during the ETL process, especially when dealing with large volumes of data? Can you provide an example of a challenging data quality issue you encountered and how you resolved it?

How do you approach designing a data model for a system that requires both high performance for read operations and efficient storage utilization? Can you give an example of a trade-off you might make in such a scenario?

Can you explain the difference between a star schema and a snowflake schema in the context of data modeling? Provide examples of when you would use each schema.

Can you explain the concept of indexing in databases and how it can improve query performance? Can you provide an example of a scenario where proper indexing significantly optimized a database operation?

Discuss the trade-offs between normalization and denormalization in database design. How would you approach optimizing a database schema considering these trade-offs and the specific requirements of a system?

Describe a situation where you had to communicate a complex idea to a non-technical stakeholder. How did you ensure effective communication and understanding? What strategies did you use to overcome any potential misunderstandings?

Can you provide an example of a time when you had to navigate a challenging team dynamic to successfully deliver a project? How did you approach the situation and what was the outcome?