You might look at the concept-oriented model [1] which is a major alternative to set-oriented approaches (including RM and MapReduce). Shortly, instead of viewing data processing as a graph of set operations, this approach treats it as a graph of operations on functions which make many data modeling/processing tasks simpler and more natural in comparision to the conventional purely set-oriented approach.

[1] Concept-oriented model: Modeling and processing data using functions: https://www.researchgate.net/publication/337336089_Concept-o...

(Disclaimer: I am the author)