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Data & Analytics · Intermediate

Data Federation

Running a single query across multiple independent databases and returning combined results.

Definition

Federated queries push work down to source systems where possible. Examples are BigQuery federated queries to Cloud SQL and Spanner, Athena federated query and Databricks Lakehouse Federation.

Example

BigQuery EXTERNAL_QUERY('connection_id', 'SELECT * FROM orders')

Exam tip

Federation queries live data in place; use it for occasional joins, not heavy repeated analytics.

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