c

Author: nameexhaustion

crates/polars-stream/src/nodes/io_sources/multi_file_reader/reader_pipelines/generic.rs

@@ -1086,6 +1086,8 @@ impl ReaderOperationPushdown<'_> {
         // * If there is both a slice and deletions, DO NOT push deletions to the reader without
         //   pushing the slice.
 
+        // If `unsupported_mapped_projection`, the file may contain a column sharing the name of
+        // the row index column, but gets renamed by the column mapping.
         let row_index = if reader_capabilities.contains(RC::ROW_INDEX)
             && !(unsupported_mapped_projection || unsupported_external_filter_mask)
         {