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Partitioning a table with card details and transactions?

SQLmedium0.4 min readPremium

Partition card/transaction tables by: (1) date (transaction_date)—most common for time-series. (2) card_id range or hash for even distribution. (3) Composite: date + card_type. Avoid over-partitioning. Example: PARTITION BY RANGE (transaction_date) or LIST (card_type). For...

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Frequency
Low
Asked at 1 company
Category
487
questions in SQL
Difficulty Split
130E|271M|86H
in this category
Total Bank
1,863
across 7 categories
Asked at these companies
Citi
Key Concepts Tested
partition

Why This Question Matters

This medium-level SQL question appears frequently in data engineering interviews at companies like Citi. While less common, it tests deeper understanding that distinguishes strong candidates. Mastering the underlying concepts (partition) will help you answer variations of this question confidently.

How to Approach This

Break this problem into components. Identify the core trade-offs involved, then walk the interviewer through your reasoning step by step. Demonstrate awareness of edge cases and production considerations - this is what separates good answers from great ones.

Expert Answer
75 words

Partition card/transaction tables by: (1) date (transaction_date)—most common for time-series. (2) card_id range or hash for even distribution. (3) Composite: date + card_type. Avoid over-partitioning. Example: PARTITION BY RANGE (transaction_date) or LIST (card_type). For billions of rows: date partition + sub-partition by card hash. Why it matters: Design choices compound at scale—wrong approach can cause 100× overhead. Scalability trade-offs: Profile before optimizing; validate on sample then full. Cost implications: Suboptimal choices multiply at billion-row scale.

The complete answer continues with detailed implementation patterns, architectural trade-offs, and production-grade considerations covering performance optimization and real-world examples.

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According to DataEngPrep.tech, this is one of the most frequently asked SQL interview questions, reported at 1 company. DataEngPrep.tech maintains a curated database of 1,863+ real data engineering interview questions across 7 categories, verified by industry professionals.

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