Method display

datafusion/expr/src/logical_plan/plan.rs:1850–2191

Return a `format`able structure with the a human readable description of this LogicalPlan node per node, not including children. For example: ```text Projection: id ``` ``` use arrow::datatypes::{DataType, Field, Schema}; use datafusion_expr::{col, lit, logical_plan::table_scan, LogicalPlanBuilder}; let schema = Schema::new(vec![Field::new("id", DataType::Int32, false)]); let plan = table_scan(So

(&self)

    /// assert_eq!("TableScan: t1", display_string);
    /// ```
    pub fn display(&self) -> impl Display + '_ {
        // Boilerplate structure to wrap LogicalPlan with something
        // that that can be formatted
        struct Wrapper<'a>(&'a LogicalPlan);
        impl Display for Wrapper<'_> {
            fn fmt(&self, f: &mut Formatter) -> fmt::Result {
                match self.0 {
                    LogicalPlan::EmptyRelation(EmptyRelation {
                        produce_one_row,
                        schema: _,
                    }) => {
                        let rows = if *produce_one_row { 1 } else { 0 };
                        write!(f, "EmptyRelation: rows={rows}")
                    }
                    LogicalPlan::RecursiveQuery(RecursiveQuery {
                        is_distinct, ..
                    }) => {
                        write!(f, "RecursiveQuery: is_distinct={is_distinct}")
                    }
                    LogicalPlan::Values(Values { values, .. }) => {
                        let str_values: Vec<_> = values
                            .iter()
                            // limit to only 5 values to avoid horrible display
                            .take(5)
                            .map(|row| {
                                let item = row
                                    .iter()
                                    .map(|expr| expr.to_string())
                                    .collect::<Vec<_>>()
                                    .join(", ");
                                format!("({item})")
                            })
                            .collect();

                        let eclipse = if values.len() > 5 { "..." } else { "" };
                        write!(f, "Values: {}{}", str_values.join(", "), eclipse)
                    }

                    LogicalPlan::TableScan(TableScan {
                        source,
                        table_name,
                        projection,
                        filters,
                        fetch,
                        ..
                    }) => {
                        let projected_fields = match projection {
                            Some(indices) => {
                                let schema = source.schema();
                                let names: Vec<&str> = indices
                                    .iter()
                                    .map(|i| schema.field(*i).name().as_str())
                                    .collect();
                                format!(" projection=[{}]", names.join(", "))
                            }
                            _ => "".to_string(),
                        };