关于docvalue fields
https://blog.csdn.net/zhanglh046/article/details/78536143
https://www.elastic.co/guide/en/elasticsearch/reference/current/search-request-docvalue-fields.html
还有就是当你索引很大,2台机的话,要拿东西的时候OS的page cache会miss
docvalue fields的意思是从建好的索引处直接返回这个值
毕竟source是一大片物理磁盘去,理论上从docvalue处拿这个值会比你source 捞要快一点,抖动会少一点