Data & analytics · reviewed in August 2026
Data warehouse
A data warehouse is a centralized database optimized for analytical queries over large volumes of historical data, as opposed to a transactional database optimized for many small, fast writes. It combines data from several sources in one place for analysis and reporting.
Frequently asked questions
How is a data warehouse different from an app's production database?
The production database is optimized for fast row-by-row operations (creating an order, updating a user); a data warehouse is optimized for reading and aggregating millions of rows at once, which would overload the transactional database.
What is a data lake and how does it differ from a data warehouse?
A data lake stores raw, unstructured data in any format; a data warehouse stores already-clean, structured data in defined schemas, ready to be queried with SQL.
How does data get into a data warehouse?
Through an ETL or ELT process that extracts data from its sources (transactional databases, APIs, files), transforms it, and loads it into the warehouse's schema, usually on a recurring schedule.