Optionally return result if partitioning is a subset of given join keys, and if so then return the subset as well as the indices of subset keys in the join keys (in order).
Optionally return result if partitioning is a subset of given join keys, and if so then return the subset as well as the indices of subset keys in the join keys (in order). Also unwraps aliases in the keys for matching against partitioning and returns a boolean indicating whether alias was unwrapped or not.
Extension to Spark's SortMergeJoinExec to avoid exchange for cases when join keys are a subset of child plan partitioning.