message: message when materializing
diff: @@ -101,6 +101,7 @@ struct AltrepVectorWrapper {
  void *Dataptr() {
  if (transformed_vector.data() == R_NilValue) {
  + R_ShowMessage("Materializing...");
  auto res = rel->GetQueryResult();
  RProtector r_varvalue;
  transformed_vector = duckdb_r_allocate(res->types[column_index], r_varvalue, res->RowCount());
  