message: need the flatten here for vector sizes test
diff: @@ -119,6 +119,7 @@ static void ExecuteExpression(vector<LogicalType> &types, vector<LogicalType> &r
  vector<Vector> slices;
  for (idx_t col_idx = 0; col_idx < args.ColumnCount() - 1; col_idx++) {
  slices.emplace_back(Vector(args.data[col_idx + 1], sel_vectors[col_idx], elem_cnt));
  + slices[col_idx].Flatten(elem_cnt);
  input_chunk.data[col_idx + 1].Reference(slices[col_idx]);
  }
  