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在使用es时，我们经常会用到聚合查询。

简单的聚合查询，已经在前面介绍过，详情见： https://www.cnblogs.com/expiator/p/13843969.html

有时，也会用到多字段聚合查询。类似于Mysql的Group By多个字段。

比如，查询统计各个地区的各个日期，各自的订单总量。

es多字段聚合

DSL的格式，如下所示：

{"size" : 0,"query" : {  },"aggregations" : {"自己命名的聚合名称1" : {"terms" : {"field" : "字段名称1","size" : 20000,"order" : {"_term" : "asc"}},"aggregations" : {"自己命名的聚合统计名称2" : {"sum" : {"field" : "字段名称2"}},"自己命名的聚合名称3" : {"terms" : {"field" : "字段名称3","size" : 20,"order" : {"_term" : "asc"}},"aggregations" : {"自己命名的聚合统计名称4" : {"sum" : {"field" : "字段名称4"}}}}}}}
} 

示例如下：

{"size" : 0,"query" : {  },"aggregations" : {"agg_area" : {"terms" : {"field" : "area","size" : 20000,"order" : {"_term" : "asc"}},"aggregations" : {"sum_area" : {"sum" : {"field" : "amount"}},"agg_day" :  {"terms" : {"field" : "day","size" : 20,"order" : {"_term" : "asc"}},"aggregations" : {"sum_day" : {"sum" : {"field" : "amount"}}}}}}}
}

es多字段聚合的java api

示例的代码如下：

public String getAggDSL() {SearchSourceBuilder searchSourceBuilder = SearchSourceBuilder.searchSource();//聚合的第二个字段AggregationBuilder dayAgg = AggregationBuilders.terms("agg_day").field("day").order(Terms.Order.aggregation(TERM, true)).size(20).subAggregation(AggregationBuilders.sum("sum_day").field("amount"));//聚合的第一个字段		AggregationBuilder areaDayAgg = AggregationBuilders.terms("agg_area").field("area").order(Terms.Order.aggregation(TERM, true)).size(10000).subAggregation(AggregationBuilders.sum("sum_area").field("amount")).subAggregation(dayAgg);		return searchSourceBuilder.query().aggregation(areaDayAgg).size(0).toString();				}

script实现es多字段聚合

es多字段聚合，对性能要求不高的话，可以使用script。

对A，B等多个字段进行聚合，那也可以直接将它们组合起来，形成A和B相关的script，
只要script的值相同，就聚合到同一组。

查询语句如下：

 {"size" : 0,"query" : {"bool" : {"filter" : [{"term" : {"过滤字段1" : {"value" : "匹配值"}}},{"term" : {"过滤字段2" : {"value" : "匹配值"}}}]}},"aggregations" : {"聚合名称" : {"terms" : {"script" : {"inline" : "doc['字段名称1'].values +'-'+ doc['字段名称2'].values","lang" : "painless"},"size" : 10000,"order" : {"排序字段" : "desc"}},"aggregations" : {"自已命令的聚合名称" : {"sum" : {"field" : "聚合求和字段"}}}}}}