聚合认知前提

桶（Buckets）——满足特定条件的文档的集合
指标（Metrics）——对桶内的文档进行统计计算

SELECT COUNT(color)
FROM table
GROUP BY color

COUNT(color) 相当于指标。
GROUP BY color 相当于桶。

一、聚合起步

1、创建索引

1.1 创建索引DSL实现

put carsPOST /cars/transactions/_bulk{ "index": {}}{ "price" : 10000, "color" : "red", "make" : "honda", "sold" : "2014-10-28" }{ "index": {}}{ "price" : 20000, "color" : "red", "make" : "honda", "so