add clarifying comment

rapidsai · Oct 18, 2021 · 4d625c8 · 4d625c8
1 parent 7c8af1f
commit 4d625c8
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/cpp/src/io/orc/reader_impl.cu b/cpp/src/io/orc/reader_impl.cu
@@ -1177,6 +1177,8 @@ table_with_metadata reader::impl::read(size_type skip_rows,
                                        const std::vector<std::vector<size_type>>& stripes,
                                        rmm::cuda_stream_view stream)
 {
+  // Selected columns at different levels of nesting are stored in different elements
+  // of `_selected_columns`; thus, size == 1 means no nested columns
   CUDF_EXPECTS(skip_rows == 0 or _selected_columns.size() == 1,
                "skip_rows is not supported by nested columns");