Real questions from top companies
Design a daily ETL pipeline to ingest API data into BigQuery.
Design a financial database system focusing on database models, schema design, partition keys, and query optimization techniques.
Design a relational data model for a sales database, incorporating normalization techniques
Design a structure (data model) that allows efficient querying of movies based on multiple search criteria (title, genre, actor, director).
Design the data model for an ETL pipeline that ingests data from a database and loads it into Snowflake
Designing backend architecture for SQL Warehouse?
Designing scalable data models - explain approach
Difference Between Truncate/Delete and Union/Union All – Performance and Usage
Explain BigQuery Architecture.
Explain CTE vs Temp Table. What are the differences and use cases?
Explain Data Modeling SCD Types (Type 1, 2, 3).
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?
Describe a cross-team data project where you had to align architectural boundaries, ownership, and SLAs. How did you handle conflicting priorities, technical debt, and the scalability of communication as the number of stakeholders grew?
Walk through a production incident where data freshness or correctness was at risk. How did you balance immediate mitigation vs. root-cause remediation? What architectural changes would prevent recurrence, and what are the cost vs. reliability trade-offs?
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?
Implement a recursive query for hierarchy (employee-manager). Explain the termination guarantees, depth limits, and when a recursive CTE becomes a scalability bottleneck. What alternatives exist for graph-scale hierarchies in Spark or a data lake?
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?
Compare Glue partition discovery with Hive MSCK/ADD PARTITION. Explain the operational and cost implications of crawler-based vs. partition-projection approaches. When does partition projection become necessary, and what are its limitations?
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