Method column_indices

datafusion/physical-expr/src/projection.rs:388–395

Extract the column indices used in this projection. For example, for a projection `SELECT a AS x, b + 1 AS y`, where `a` is at index 0 and `b` is at index 1, this function would return `[0, 1]`. Repeated indices are returned only once, and the order is ascending.

(&self)

    /// this function would return `[0, 1]`.
    /// Repeated indices are returned only once, and the order is ascending.
    pub fn column_indices(&self) -> Vec<usize> {
        self.exprs
            .iter()
            .flat_map(|e| collect_columns(&e.expr).into_iter().map(|col| col.index()))
            .sorted_unstable()
            .dedup()
            .collect_vec()
    }

    /// Extract the ordered column indices for a column-only projection.
    ///