Function empty_child

datafusion/optimizer/src/propagate_empty_relation.rs:254–271

(plan: &LogicalPlan)

}

fn empty_child(plan: &LogicalPlan) -> Result<Option<LogicalPlan>> {
    match plan.inputs()[..] {
        [child] => match child {
            LogicalPlan::EmptyRelation(empty) => {
                if !empty.produce_one_row {
                    Ok(Some(LogicalPlan::EmptyRelation(EmptyRelation {
                        produce_one_row: false,
                        schema: Arc::clone(plan.schema()),
                    })))
                } else {
                    Ok(None)
                }
            }
            _ => Ok(None),
        },
        _ => plan_err!("plan just can have one child"),
    }
}

/// Builds a Projection that replaces one side of an outer join with NULL literals.
///