Reviewed by Aditya Kumar · Last reviewed 2026-03-24
**Architectural Logic**: All three assign ordinals over partitions but differ in tie-handling and downstream semantics. ROW_NUMBER(): Deterministic unique ordering—required for deduplication (pick one row per key). RANK(): Ties get same rank, next rank skips—classic leaderboard...
Red Flag: Using ROW_NUMBER for leaderboards without tie-breaker—non-deterministic results. Pro-Move: 'For dedup I use ROW_NUMBER with ORDER BY updated_at DESC—deterministic and traceable.'
This medium-level SQL question appears frequently in data engineering interviews at companies like Presidio, Swiggy. 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.
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.
Architectural Logic: All three assign ordinals over partitions but differ in tie-handling and downstream semantics. ROW_NUMBER(): Deterministic unique ordering—required for deduplication (pick one row per key). RANK(): Ties get same rank, next rank skips—classic leaderboard (e.g., Olympic medals). DENSE_RANK(): Ties get same rank, no skip—"top N per category" when N must be exact count. Why: ROW_NUMBER needs ORDER BY with a tie-breaker for determinism. RANK reflects competitive gaps. DENSE_RANK ensures 'top 10' returns 10 entities when ties exist. Scalability: Each requires a sort within partition; DENSE_RANK avoids secondary sort for gaps. At scale, narrow PARTITION BY reduces sort size. Cost: RANK with many ties can produce larger intermediate state than DENSE_RANK. Example: 95,90,90,85 → RN: 1,2,3,4. RANK: 1,2,2,4. DENSE: 1,2,2,3.
Red Flag: Using ROW_NUMBER for leaderboards without tie-breaker—non-deterministic results. Pro-Move: 'For dedup I use ROW_NUMBER with ORDER BY updated_at DESC—deterministic and traceable.'
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According to DataEngPrep.tech, this is one of the most frequently asked SQL interview questions, reported at 2 companies. DataEngPrep.tech maintains an editor-reviewed database of 1,863 data engineering interview questions across 7 categories.