[ElasticSearch] Aggregation :Met

SQL场景：Metrics查询

SELECT avg(privce)  FROM table where price >= 10000 and price <= 35000 GROUP BY color

查询在一定价格区间的，按颜色分组的平均值
Aggregation API:
在API实现上是先做过滤再聚合，分桶后加入Metrics聚合：

GET /cars/transactions/_search
{
    "size" : 0,
    "query": {
        "range" : {
            "price" : {
                "gte" : 10000,
                "lt" :  35000
            }
        }
    },
    "aggs" : { 
        "popular_colors" : { 
            "terms" : { 
              "field" : "color"
            },
            "aggs": {
              "price_avg": {
                "avg": {
                  "field": "price"
                }
              }
            }
        }
    }
}

结果：

image.png

java API：

def aggTest3(): Unit = {
    import scala.collection.JavaConverters._
    val rangeQuery = QueryBuilders.rangeQuery("price").gte(10000).lt(35000)
    val agg = AggregationBuilders
      .terms("color")
      .field("color")
      .order(Terms.Order.count(false))
    val avg = AggregationBuilders
    .avg("price")// also sum / max
    .field("price")
    agg.subAggregation(avg)
    val searchRes = queryBuilder
      .setQuery(rangeQuery)
      .addAggregation(agg)
      .execute()
      .actionGet()
    searchRes.getAggregations.get("color").asInstanceOf[Terms].getBuckets.asScala.foreach{ bucket =>
      println(s"key: ${bucket.getKeyAsString}, value ${bucket.getDocCount}")
      bucket.getAggregations.getAsMap.asScala.foreach{ agg =>
        println(s"key: ${agg._1}, value ${agg._2.asInstanceOf[InternalAvg].getValue}")
      }
      println(s"----------------------------------------")
    }
  }

结果：

image.png