**SQL**: SELECT user_id, AVG(duration) AS avg_session_duration FROM (SELECT user_id, session_id, MAX(ts) - MIN(ts) AS duration FROM events GROUP BY user_id, session_id) t GROUP BY user_id. **Logic**: Inner query computes per-session duration; outer averages per user....
Pro-Move: 'We exclude sessions with 1 event and cap at 24hr—bots and errors skewed our early metrics.' Red Flag: Not defining session—need session_id or timeout logic.
This easy-level General/Other question appears frequently in data engineering interviews at companies like Expedia. While less common, it tests deeper understanding that distinguishes strong candidates. Mastering the underlying concepts (sql) will help you answer variations of this question confidently.
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.
SQL: SELECT user_id, AVG(duration) AS avg_session_duration FROM (SELECT user_id, session_id, MAX(ts) - MIN(ts) AS duration FROM events GROUP BY user_id, session_id) t GROUP BY user_id. Logic: Inner query computes per-session duration; outer averages per user. Best practice: Handle single-event sessions (duration 0); consider excluding bots.
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Analyze My Answer — FreeAccording to DataEngPrep.tech, this is one of the most frequently asked General/Other 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.