Answer: Materialized view

The question asks for a Snowflake database object that is derived from a query specification, stored for later use, and can speed up expensive aggregation on large datasets. A materialized view (option D) fits all these criteria: it is created from a query definition, physically stores the query results for persistence, and is specifically designed to improve performance of complex queries like aggregations by precomputing and storing results. The community discussion shows 100% consensus on D, with a reference to Snowflake documentation confirming materialized views are used for this purpose. Other options are less suitable: temporary tables (A) are session-scoped and not persistent; external tables (B) reference external data sources rather than storing query results; secure views (C) provide security but do not physically store data, so they don't accelerate aggregations through precomputation.

Author: LeetQuiz Editorial Team