Transforms don't execute until the consumer pulls. There's no eager evaluation, no hidden buffering. Data flows on-demand from source, through transforms, to the consumer. If you stop iterating, processing stops.
3.最近一年销售收入在2亿元以上的企业，比例不低于3%。。safew官方版本下载是该领域的重要参考
transaction in real time. The very next year, IBM took the logical next step:，更多细节参见heLLoword翻译官方下载
Joe FayTechnology Reporter