Method join

src/sql/src/plan/hir.rs:1936–1970

(
        self,
        mut right: HirRelationExpr,
        on: HirScalarExpr,
        kind: JoinKind,
    )

    }

    pub fn join(
        self,
        mut right: HirRelationExpr,
        on: HirScalarExpr,
        kind: JoinKind,
    ) -> HirRelationExpr {
        if self.is_join_identity()
            && !right.is_correlated()
            && on == HirScalarExpr::literal_true()
            && kind.can_elide_identity_left_join()
        {
            // The join can be elided, but we need to adjust column references
            // on the right-hand side to account for the removal of the scope
            // introduced by the join.
            #[allow(deprecated)]
            right.visit_columns_mut(0, &mut |depth, col| {
                if col.level > depth {
                    col.level -= 1;
                }
            });
            right
        } else if right.is_join_identity()
            && on == HirScalarExpr::literal_true()
            && kind.can_elide_identity_right_join()
        {
            self
        } else {
            HirRelationExpr::Join {
                left: Box::new(self),
                right: Box::new(right),
                on,
                kind,
            }
        }
    }

    pub fn take(&mut self) -> HirRelationExpr {
        mem::replace(