I came across this proposal to support analytics on unstructured data. It proposes extensions to relational algebra to handle unstructured data called "Multidimensional-relational-algebra" or MRA:
https://slamdata.com/what-is-multidimensional-relational-algebra/Apart from this spec in purescript: https://github.com/slamdata/purescript-mra
I could not find any formal spec.
I was attempting to understand this as a way to treat both JSON and DB views (joins on tables) as "nested objects". Any pointers about MRA (above)?