Object[] newFromRow)
    throws IOException
  {
    IndexCursor toCursor = joiner.getToCursor();
    List<? extends Index.Column> fromCols = joiner.getColumns();
    List<? extends Index.Column> toCols = joiner.getToIndex().getColumns();
    Object[] toRow = new Object[joiner.getToTable().getColumnCount()];

    for(Iterator<Row> iter = joiner.findRows(oldFromRow)
          .setColumnNames(Collections.<String>emptySet())
          .iterator(); iter.hasNext(); ) {
      iter.next();

      // create update row for "to" table
      Arrays.fill(toRow, Column.KEEP_VALUE);
      for(int i = 0; i < fromCols.size(); ++i) {