**Architectural Logic**: DELETE: DML; row-by-row (or batch); logged per row; supports WHERE; triggers fire; slower. TRUNCATE: DDL; deallocates data pages; minimal logging; no WHERE; resets identity; faster. **Why**: DELETE for conditional removal, audit trails, cascade. TRUNCATE...
This easy-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.
Start by clearly defining the core concept being asked about. Interviewers want to see that you understand the fundamentals before diving into implementation details. Structure your answer with a definition, then explain the practical application with a concise example.
Architectural Logic: DELETE: DML; row-by-row (or batch); logged per row; supports WHERE; triggers fire; slower. TRUNCATE: DDL; deallocates data pages; minimal logging; no WHERE; resets identity; faster. Why: DELETE for conditional removal, audit trails, cascade. TRUNCATE for full table clear (e.g., staging before load). Scalability: DELETE locks rows/pages; long-running on large tables blocks. TRUNCATE is metadata change + page deallocationānear-instant. Cost: DELETE writes to transaction log per row; TRUNCATE logs extent deallocations. Use TRUNCATE for staging; DELETE for production with conditions.
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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 a curated database of 1,863+ real data engineering interview questions across 7 categories, verified by industry professionals.