Function grouping_set_expr_count

datafusion/expr/src/utils.rs:55–67

Count the number of distinct exprs in a list of group by expressions. If the first element is a `GroupingSet` expression then it must be the only expr.

(group_expr: &[Expr])

/// Count the number of distinct exprs in a list of group by expressions. If the
/// first element is a `GroupingSet` expression then it must be the only expr.
pub fn grouping_set_expr_count(group_expr: &[Expr]) -> Result<usize> {
    if let Some(Expr::GroupingSet(grouping_set)) = group_expr.first() {
        if group_expr.len() > 1 {
            return plan_err!(
                "Invalid group by expressions, GroupingSet must be the only expression"
            );
        }
        // Groupings sets have an additional integral column for the grouping id
        Ok(grouping_set.distinct_expr().len() + 1)
    } else {
        grouping_set_to_exprlist(group_expr).map(|exprs| exprs.len())
    }
}

/// Internal helper that generates indices for powerset subsets using bitset iteration.
/// Returns an iterator of index vectors, where each vector contains the indices