Real questions from top companies in SQL · medium
What are BigQuery Slots?
What are Slowly Changing Dimensions (SCD), and how would you implement them for tracking customer data changes?
What are partitioning strategies in Redshift?
What are some best practices for writing efficient SQL queries?
What are the differences between normalization and denormalization? When would you use a denormalized structure?
What challenges arise with duplicate records, and how do you address them?
What factors determine the optimal number of partitions for a large file?
What is Left Anti Join and its use case?
What is Redshift Spectrum, and how does it differ from standard Redshift queries?
What is UNNEST and provide a query example?
What is a Kafka topic, and how do you choose the number of partitions for it?
What is a cross-join?
What is a semi-join?
What is dynamic partition pruning, and how does it optimize query execution?
What is the difference between UNION and UNION ALL? Which one is faster and why?
What is the difference between static and dynamic partitioning in Hive?
What strategies would you use to manage dynamic partitions efficiently?
When would you choose partitioning over bucketing, or vice versa?
Write a SQL query to find departments with more than 10 employees.
Write a SQL query to find house with Avg(score) > 70.
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