Function expr::permutation_for_arrangement [−][src]
pub fn permutation_for_arrangement<B: FromIterator<(usize, usize)>>(
key: &[MirScalarExpr],
unthinned_arity: usize
) -> (B, Vec<usize>)
Expand description
Return the map associating columns in the logical,
unthinned representation of a collection to columns in the
thinned representation of the arrangement corresponding to key
.
Returns the permutation and the thinning expression that should be used to create the arrangement.
The permutations and thinning expressions generated here will be tracked in
dataflow::plan::AvailableCollections
; see the
documentation there for more details.