Function equal_sparse 

fn equal_sparse(
    lhs: &ArrayData,
    rhs: &ArrayData,
    type_ids: &[i8],
    fields: &UnionFields,
    lhs_start: usize,
    rhs_start: usize,
) -> bool

Compares type_ids.len() slots of two sparse unions whose type ids over that range are already known to be equal.

Only the child selected by each slot’s type id contributes to the logical value of a sparse union; the values held by the other children at that slot are arbitrary and must not affect equality. Consecutive slots that select the same child are compared as a single range of that child.