docs: private static Scanner setupAllTreeScanner(final TSDB tsdb) {
      final byte[] start = new byte[TREE_ID_WIDTH];
      final byte[] end = new byte[TREE_ID_WIDTH];
      Arrays.fill(end, (byte)0xFF);
      
      final Scanner scanner = tsdb.getClient().newScanner(tsdb.treeTable());
      scanner.setStartKey(start);
      scanner.setStopKey(end);   
      scanner.setFamily(TREE_FAMILY);
      
      // set the filter to match only on TREE_ID_WIDTH row keys
      final StringBuilder buf = new StringBuilder(20);
      buf.append("(?s)"  // Ensure we use the DOTALL flag.
          + "^\\Q");
      buf.append("\\E(?:.{").append(TREE_ID_WIDTH).append("})$");
      scanner.setKeyRegexp(buf.toString(), CHARSET);
      return scanner;
    }