fn label_runs(columns: &[&ArrayRef], rows: usize) -> Result<Vec<Range<usize>>>Expand description
Ranges of consecutive rows whose label values are all equal.
arrow::compute::partition computes the same ranges, but its contract takes
lexicographically sorted columns, which query output is not: range queries
run without the plan’s output sort, and sort/topk order by value.
distinct is element-wise, so it holds for any row order, and its null
handling is the one a series key needs: a null label and an empty one are
distinct, and two nulls are not.