def METHOD_NAME(index='documents', size=1000):
    """Get a list of records PIDs for the given index.
    :param str index: Index to search for records.
    :param int size: Number of records to return.
    """
    results = Search(using=Elasticsearch(),
                     index=index)[0:size].source(includes=['pid']).execute()
    return [item['pid'] for item in results]