Does a view contain data?
Interviewer Expectations for this Question
01
Core Competency
Assesses fundamental understanding of SQL & Databases conventions, runtime behavior, and memory/performance considerations.
02
Evaluation Criteria
Hiring managers look for precision, avoidance of ambiguous jargon, and ability to explain trade-offs under real production conditions.
Comprehensive Model Answer
Verified Solution
Standard SQL views do NOT contain data.
- Standard Views (Virtual): Contain only a stored SQL query definition in the data dictionary. Every query against the view executes dynamically against the underlying base tables.
- Materialized Views (Cached on Disk): Supported in PostgreSQL, Oracle, and SQL Server (and via plugins/triggers in MySQL), materialized views physically cache query results on disk and must be periodically refreshed (
REFRESH MATERIALIZED VIEW).
Candidate Response Strategy & Interview Tips
- Start with a concise one-sentence summary: Deliver a direct, confident answer first before expanding into nuances.
- Demonstrate real-world trade-offs: Discuss where this approach excels and when you would avoid it in production systems.
- Discuss complexity & edge cases: Proactively explain time/space complexity or boundary conditions (null values, scale limits).
- Prepare for interviewer follow-ups: Technical hiring panels frequently probe deeper into concurrency, backward compatibility, or alternative libraries.