Hi, an informative article!

I'm a bit confused about the description of spatial joins in Cosmos DB. The article lists, as one of Cosmos DB operations, "Spatial join queries combine two datasets or more with a spatial predicate, such as distance relations". But all the examples do range/distance queries with a constant region, none join two datasets.

I could not figure out how to join two datasets in Cosmos DB at all, the Cosmos DB Help describes only intra-document joins, not joins between different documents or collections:

https://docs.microsoft.com/en-us/azure/cosmos-db/sql-query-join

Could you give an example of a spatial join query between different datasets / collections?