How to design index/types for documents which has to be sorted individually over multiple categories

A beginner question:
I know its a typical relational setup, but i wish to know what would be best way to manage this within ES:

I have documents which relate to multiple categories and a join table which holds sorting value for any document to category relation.
What is best design and way to get those documents from ES matching a certain category and respect this category-individual sorting value:

  1. indices for each category holding redundant documents with a single catsorting field
  2. one index but multiple types for each category holding redundant documents with a single catsorting field
  3. any solutions to avoid redundancy?

Is there a way to use dynamic fields as sorting fields? I was thinking of dynamically adding catsorting_<category_id> fields and then sort over this field if it exists or something like that...

Thanks for your help!

No hints anybody?