pub fn join_permutations(
    key_arity: usize,
    stream_permutation: HashMap<usize, usize>,
    thinned_stream_arity: usize,
    lookup_permutation: HashMap<usize, usize>
) -> HashMap<usize, usize>
Expand description

Given the permutations (see permutation_for_arrangement and (dataflow::plan::AvailableCollections) corresponding to two collections with the same key arity, computes the permutation for the result of joining them.