Function datafusion_physical_plan::windows::get_ordered_partition_by_indices

pub fn get_ordered_partition_by_indices(
    partition_by_exprs: &[Arc<dyn PhysicalExpr>],
    input: &Arc<dyn ExecutionPlan>,
) -> Vec<usize>

This function calculates the indices such that when partition by expressions reordered with the indices resulting expressions define a preset for existing ordering. For instance, if input is ordered by a, b, c and PARTITION BY b, a is used, this vector will be [1, 0]. It means that when we iterate b, a columns with the order [1, 0] resulting vector (a, b) is a preset of the existing ordering (a, b, c).