Method intersect_or_except

datafusion/expr/src/logical_plan/builder.rs:1377–1435

Process intersect or except

(
        left_plan: LogicalPlan,
        right_plan: LogicalPlan,
        join_type: JoinType,
        is_all: bool,
    )

    /// Process intersect or except
    fn intersect_or_except(
        left_plan: LogicalPlan,
        right_plan: LogicalPlan,
        join_type: JoinType,
        is_all: bool,
    ) -> Result<LogicalPlan> {
        let left_len = left_plan.schema().fields().len();
        let right_len = right_plan.schema().fields().len();

        if left_len != right_len {
            return plan_err!(
                "INTERSECT/EXCEPT query must have the same number of columns. Left is {left_len} and right is {right_len}."
            );
        }

        // Requalify sides if needed to avoid duplicate qualified field names
        // (e.g., when both sides reference the same table)
        let left_builder = LogicalPlanBuilder::from(left_plan);
        let right_builder = LogicalPlanBuilder::from(right_plan);
        let (left_builder, right_builder, _requalified) =
            requalify_sides_if_needed(left_builder, right_builder)?;
        let left_plan = left_builder.build()?;
        let right_plan = right_builder.build()?;

        let join_keys = left_plan
            .schema()
            .fields()
            .iter()
            .zip(right_plan.schema().fields().iter())
            .map(|(left_field, right_field)| {
                (
                    (Column::from_name(left_field.name())),
                    (Column::from_name(right_field.name())),
                )
            })
            .unzip();
        if is_all {
            LogicalPlanBuilder::from(left_plan)
                .join_detailed(
                    right_plan,
                    join_type,
                    join_keys,
                    None,
                    NullEquality::NullEqualsNull,
                )?
                .build()
        } else {
            LogicalPlanBuilder::from(left_plan)
                .distinct()?
                .join_detailed(
                    right_plan,
                    join_type,
                    join_keys,
                    None,
                    NullEquality::NullEqualsNull,
                )?
                .build()
        }