Method except

src/sql/src/plan/hir.rs:57–66

(all: &bool, lhs: Self::Relation, rhs: Self::Relation)

impl AlgExcept for Hir {
    fn except(all: &bool, lhs: Self::Relation, rhs: Self::Relation) -> Self::Relation {
        if *all {
            let rhs = rhs.negate();
            HirRelationExpr::union(lhs, rhs).threshold()
        } else {
            let lhs = lhs.distinct();
            let rhs = rhs.distinct().negate();
            HirRelationExpr::union(lhs, rhs).threshold()
        }
    }

    fn un_except<'a>(expr: &'a Self::Relation) -> Option<Except<'a, Self>> {
        let mut result = None;