Context

Teams often rely on SQL to explore and summarize large datasets before building dashboards, models, or pipelines. Interviewers ask this question to understand both your analytical workflow and how efficiently you work with data at scale.

Core Question

Explain the methods you use to analyze large datasets in SQL. Your answer should cover:

1. How you narrow the scope of data before deep analysis
2. How you use aggregations and grouping to identify patterns
3. How you validate data quality and investigate anomalies
4. How you keep queries efficient on large tables

Scope Guidance

Keep the answer practical and SQL-focused. The interviewer is not looking for advanced distributed systems design here; they want a clear approach for exploring large tables, summarizing trends, checking assumptions, and writing efficient PostgreSQL queries.