Method stat_column_expr

datafusion/pruning/src/pruning_predicate.rs:808–839

Rewrites column_expr so that all appearances of column are replaced with a reference to either the min or max statistics column, while keeping track that a reference to the statistics column is required for example, an expression like `col("foo") > 5`, when called with Max would result in an expression like `col("foo_max") > 5` with the appropriate entry noted in self.columns

(
        &mut self,
        column: &phys_expr::Column,
        column_expr: &Arc<dyn PhysicalExpr>,
        field: &Field,
        stat_type: StatisticsType,
    )

    /// with Max would result in an expression like `col("foo_max") >
    /// 5` with the appropriate entry noted in self.columns
    fn stat_column_expr(
        &mut self,
        column: &phys_expr::Column,
        column_expr: &Arc<dyn PhysicalExpr>,
        field: &Field,
        stat_type: StatisticsType,
    ) -> Result<Arc<dyn PhysicalExpr>> {
        let (idx, need_to_insert) = match self.find_stat_column(column, stat_type) {
            Some(idx) => (idx, false),
            None => (self.columns.len(), true),
        };

        let column_name = column.name();
        let stat_column_name = match stat_type {
            StatisticsType::Min => format!("{column_name}_min"),
            StatisticsType::Max => format!("{column_name}_max"),
            StatisticsType::NullCount => format!("{column_name}_null_count"),
            StatisticsType::RowCount => "row_count".to_string(),
        };

        let stat_column = phys_expr::Column::new(&stat_column_name, idx);

        // only add statistics column if not previously added
        if need_to_insert {
            // may be null if statistics are not present
            let nullable = true;
            let stat_field =
                Field::new(stat_column.name(), field.data_type().clone(), nullable);
            self.columns.push((column.clone(), stat_type, stat_field));
        }
        rewrite_column_expr(Arc::clone(column_expr), column, &stat_column)
    }

    /// rewrite col --> col_min
    fn min_column_expr(