fetchNextBatch example

return new \IteratorIterator($statement);
  }

  /** * Position the iterator to the following row. */
  protected function fetchNextRow() {
    $this->getIterator()->next();
    // We might be out of data entirely, or just out of data in the current     // batch. Attempt to fetch the next batch and see.     if ($this->batchSize > 0 && !$this->getIterator()->valid()) {
      $this->fetchNextBatch();
    }
  }

  /** * Prepares query for the next set of data from the source database. */
  protected function fetchNextBatch() {
    $this->batch++;
    unset($this->iterator);
    $this->getIterator()->rewind();
  }