SPARQL/Federated query

Federated query
Federated query is the ability to take a query and provide solutions based on information from many different sources.

A building block is the ability to have one query be able to issue a query on another SPARQL endpoint during query execution.

Example
Federated query comparing Wikidata and UK Parliament database, to show differences of more than 10km in locations of UK parliamentary constituencies (source Wikidata:Wikidata:Status updates/2019 06 10)

SPARQL Federation endpoints
Not all endpoints are allowed by Wikidata Query Service. See the list of allowed endpoints on SPARQL Federation endpoints.

You can nominate more endpoints at the Wikidata:SPARQL federation input.