fn column_sum(rb: &RecordBatch, name: &str, per_row: u32) -> Option<u64>Expand description
Sum a non-nullable UInt32 mesh column, dividing each value by
per_row first. The division is PER ROW, not on the total, because
build_mesh_tables counts index-table rows the same way — one row per
indices.len() / 3 per mesh, so a mesh whose index count is not a
multiple of 3 rounds down on its own, not against its neighbours.