Function mz_transform::semijoin_idempotence::semijoin_bijection

fn semijoin_bijection(
    inputs: &[MirRelationExpr],
    equivalences: &Vec<Vec<MirScalarExpr>>,
) -> Option<(BTreeMap<usize, usize>, BTreeMap<usize, usize>)>

Determines bijection between equated columns of a binary join.

Returns nothing if not a binary join, or if any equivalences are not of two opposing columns. Returned maps go from the column of the first input to those of the second, and vice versa.