describe lateral join use case for rdf & timeseries data

[VladimirAlexiev]

@kenwenzel in eclipse-rdf4j/rdf4j#4315 (related to w3c/sparql-dev#100)

we first query structural data from an RDF store and then related time-series data
I have also some use cases for lateral joins.

I'm highly interested to learn how you mix rdf and timeseries querying.
Do you have this written up somewhere, have I missed it?

[kenwenzel]

The short answer is: It currently works because RDF4J's default join implementation switches the direction if either the left or the right side initially has an empty result. The KVIN service does only return results if the item (the subject) is already bound.