Federated queries allow a single query to access and combine data from multiple data sources without physically moving all data into one location. Instead of centralizing data first, federated queries retrieve and join data across systems in real time.

For example, a federated query might combine:

• Data from a cloud data warehouse

• Data from an operational database

• Data from an external API

From a BI perspective, federated queries enable faster access to distributed data and reduce data duplication. They are useful when data cannot be easily replicated due to size, cost, or compliance reasons.

Technically, federated queries rely on connectors, query engines, and optimization layers that push computation to source systems where possible. Examples include BigQuery federated queries, Presto/Trino, and some BI platform integrations.

Advantages include:

• Reduced data movement

• Real-time access to source data

• Lower storage duplication

However, federated queries can introduce:

• Performance bottlenecks

• Dependency on source system availability

• Complex query optimization challenges

Because of this, federated queries are often used selectively for exploration or specific use cases rather than core reporting.

Federated queries support flexible analytics in modern data architectures, especially in hybrid and multi-cloud environments.