What is a materialized view?

• A. A pre-computed data set derived from a query and stored for later use
• B. A live view that always shows base table data
• C. A synonym for a view
• D. A temporary table created during a query

Answer: (A)

A materialized view is a pre-computed data set derived from a query and stored for later use. It saves the results of a complex query so subsequent requests can read the precomputed data instead of re-running the whole operation. This speeds up repeated analytics, especially when you have heavy joins or aggregations over large tables.

Unlike a regular view, which is only a saved query that runs every time you fetch it, a materialized view actually stores the data on disk and must be refreshed when the underlying base data changes. The system can refresh it automatically or on demand, trading off storage and refresh cost for faster read performance.