What is a view, and how does a materialized view differ?
Options
- A view saves a query run on read; a materialized view saves a result (Correct option)
- A view is a copy of the database; a materialized view is its backup
- A view is always faster than a materialized view of the same query
- There is no difference between a view and a materialized view
Answer
A view stores a saved query that runs each time you read it; a materialized view stores the query result physically and must be refreshed
Why
A view is a saved SELECT with a name: SELECT * FROM active_customers. It stores no data; each read re-runs the query. It simplifies queries and can hide columns for security.
A materialized view stores the result on disk (like a cached table). Reads are fast, but data can be stale until you refresh it (REFRESH MATERIALIZED VIEW).
Use materialized views for heavy reports.
Remember
View = saved query. Materialized view = saved result.