Real questions from top companies in SQL · hard
Difference Between Truncate/Delete and Union/Union All – Performance and Usage
Explain BigQuery Architecture.
Articulate the architectural decisions, scalability trade-offs, and cost implications of designing an AWS data platform. How would you justify glue vs. EMR, Redshift vs. Athena, and when would each choice become cost-prohibitive at scale?
Explain the architectural rationale for using LeftAntiJoin vs. NOT IN vs. NOT EXISTS in a distributed context. When does LeftAntiJoin become a performance or scalability bottleneck, and how do broadcast vs. shuffle joins affect cost?
Explain the architectural trade-offs when optimizing a query on 100M+ rows: indexing vs. partitioning vs. materialized views. When does each approach become cost-prohibitive or operationally burdensome, and how do you quantify impact?
Explain bloom filters in Spark: how they reduce I/O and when they introduce false positives that hurt performance. What are the scalability and cost implications of enabling dynamic partition pruning and bloom filter pushdown at petabyte scale?
Design a star schema for retail analytics (e.g., Adidas). Explain the dimensional modeling choices, SCD strategy, and how you would scale this schema for global multi-currency, multi-region deployments. What are the refresh and storage cost implications?
Explain the Medallion Architecture (Bronze, Silver, Gold).
Given a CSV file with raw customer transactions, design an ETL pipeline that cleans data, aggregates total sales by region and product, and loads into target table
How do you design a scalable and fault-tolerant data warehouse on a cloud platform?
How would you design a data model for an e-commerce platform?
How would you optimize a SQL query for better performance when working with large datasets?
In Python, process a large CSV in chunks and remove duplicate records based on email and timestamp.
Indexing - True/False question on indexes and query optimization
Kafka Basics - architecture, topics, partitions, producers, consumers, Zookeeper
SQL Query Design: employees with highest salaries within each department
Schema Design: Star vs. Snowflake schema differences
Snowflake Tech Stack: Deployment on Azure, cluster sizing considerations, and overall data warehouse design?
Time and cost comparisons for executing the same query in Snowflake and Spark.
What are the benefits of BigQuery Warehouse?
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