Function compare_rows 

pub fn compare_rows(
    sort: &Vec<(usize, bool)>,
    a: &OwnedRow,
    b: &OwnedRow,
) -> Ordering

Compare two owned rows under a sort spec (asc/desc per column). The common short sorts (one/two columns) are unrolled to drop iterator overhead on the hottest path. Each cell is borrowed via as_ref() and fed to the Value<'_> comparator — no allocation.