docs: @Override
      public boolean advanceNextPosition()
      {
          boolean needNextRows = !started || !nextRows.hasNext();
  
          if (!started) {
              started = true;
              nanoStart = System.nanoTime();
          }
  
          if (needNextRows) {
              currentRow = null;
              try {
                  do {
                      if (!scanner.hasMoreRows()) {
                          return false;
                      }
  
                      nextRows = scanner.nextRows();
                  }
                  while (!nextRows.hasNext());
                  log.debug("Fetched " + nextRows.getNumRows() + " rows");
              }
              catch (KuduException e) {
                  throw new RuntimeException(e);
              }
          }
  
          currentRow = nextRows.next();
          totalBytes += getRowLength();
          return true;
      }