**RLS (Row-Level Security)**: Adds predicate to every query; can use index if predicate column indexed; complex predicates = slower. **Column masking**: Per-row computation; adds overhead. **Result caching**: Speeds repeat queries; invalidated on write. **Trade-off**: Security...
This easy-level SQL question appears frequently in data engineering interviews at companies like TCS. 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.
RLS (Row-Level Security): Adds predicate to every query; can use index if predicate column indexed; complex predicates = slower. Column masking: Per-row computation; adds overhead. Result caching: Speeds repeat queries; invalidated on write. Trade-off: Security vs. latency. Design policies with indexed columns; test EXPLAIN with RLS enabled.
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Analyze My Answer — FreeAccording 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.