This workflow demonstrates how to use flow variable of Collection type to specify grouping columns in GroupBy node. Different set of grouping columns are defined in Table Creator node after which Chunk Loop Start node is utilized with 1 row per chunk. Then inside loop flow variable of Collection type is created and use in GroupBy node. With Loop End node results are concatenated.
This is a companion discussion topic for the original entry at https://kni.me/w/jHzomdVz-DTrlNMo