code: private void updateTriples(Set<Triple> set, boolean delete)
              throws ResourceIndexException {
          try {
              if (delete) {
                  _writer.delete(getTripleIterator(set), _syncUpdates);
              } else {
                  _writer.add(getTripleIterator(set), _syncUpdates);
              }
          } catch (Exception e) {
              throw new ResourceIndexException("Error updating triples", e);
          }
      }
docs: Applies the given adds or deletes to the triplestore. If _syncUpdates is
  true, changes will be flushed before returning.