Union query across all named graphs

[adlerfaulkner]

Is there a way in which I can use communica, and more importantly any rdf/js query engine, where the default graph is a union of all named graphs?

Such functionality is mentioned as possible in the RDF/JS Query Specification, though I am not sure how to set that option when using quadstore-comunica or @comunica/query-sparql-rdfjs.

I understand that this is dependent on the SPARQL implementation but I am used to it because that's what AWS Neptune does https://docs.aws.amazon.com/neptune/latest/userguide/best-practices-sparql.html#best-practices-sparql-query

[adlerfaulkner]

Seems like this could be due to SparqlAlgebra.js defaulting to setting the graph to DefaultGraph for all triple patterns not wrapped in GRAPH ?g { ... } as shown here rather than undefined or null as mentioned in the RDF/JS Query Specification

[rubensworks]

This is possible by enabling this flag: https://comunica.dev/docs/query/advanced/context/#17--union-default-graph

[adlerfaulkner]

Ah great, thanks! I looked for this for a while! I think from a usability perspective on Communica it would really help to be able to search the documentation. I think I was also thrown off track by the fact that options like this are specified through context. I was relating context to JSON-LD context and thus thought it was only for prefixes and baseIRI. Maybe consider renaming it to options?