What is Data Warehouse

Definition

A data warehouse is a centralised analytical database optimised for querying large volumes of structured, integrated, historical data, organised into schemas designed for reporting and analysis rather than transaction processing, serving as the single source of truth for business intelligence.

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Delivers fast analytical queries over years of integrated, structured history
Provides one consistent, conformed source of truth for enterprise reporting
Separates analytical load from operational systems so neither slows the other
Supports complex aggregations and joins through schemas tuned for analysis

Real World Example

A retail chain consolidates sales, inventory, and supply-chain data into a data warehouse, enabling analysts to compare same-store performance across years and regions in a single, fast query.

FAQs

How does a data warehouse differ from a database?

A warehouse is optimised for analytical queries over historical, integrated data, while an operational database is tuned for fast individual transactions.

What schema designs do warehouses use?

Star and snowflake schemas with fact and dimension tables are common because they make analytical queries efficient and intuitive.

How does a warehouse differ from a data lake?

A warehouse stores structured, modelled data ready for analysis, while a lake stores raw data of any format for flexible later processing.