private BibTrees fetchResultSet(int batchSize, BatchStatistics batchStatistics, Boolean isBibOnly)
      throws Exception {
    StopWatch stopWatch = new StopWatch();
    stopWatch.start();
    BibTrees bibTrees = new BibTrees();
    int count = 0;
    if (batchSize <= 0) {
      return bibTrees;
    }
    while (bibResultSet.next()) {
      count++;
      BibTree bibTree = new BibTree();
      Bib bib = fetchBibRecord();
      bibTree.setBib(bib);
      if (!isBibOnly) {
        List<HoldingsTree> holdingsList =
            fetchHoldingsTreeForBib(Integer.parseInt(bib.getLocalId()));
        bibTree.getHoldingsTrees().addAll(holdingsList);
        batchStatistics.addHoldingsCount(holdingsList.size());

        for (HoldingsTree holdingsTree : holdingsList) {
          batchStatistics.addItemCount(holdingsTree.getItems().size());
        }
      }

      bibTrees.getBibTrees().add(bibTree);
      if (count == batchSize) {
        break;
      }
    }
    stopWatch.stop();
    batchStatistics.addTimeTaken(stopWatch.getTotalTimeMillis());
    batchStatistics.addBibCount(bibTrees.getBibTrees().size());
    return bibTrees;
  }