ElasticSearch5.X嵌套桶（三）

短命女 2022-06-06 14:08 145阅读 0赞

## 嵌套桶[编辑][Link 1] ##

（测试数据：[http://blog.csdn.net/wwd0501/article/details/78501842][http_blog.csdn.net_wwd0501_article_details_78501842]）在我们使用不同的嵌套方案时，聚合的力量才能真正得以显现。 在前例中，我们以及看到如何将一个度量嵌入桶中，它的功能已经十分强大了。

但真正令人激动的分析来自于将桶嵌套进 另外一个桶 所能得到的结果。 现在，我们想知道每个颜色的汽车制造商的分布：

GET /cars/transactions/_search
    {
       "size" : 0,
       "aggs": {
          "colors": {
             "terms": {
                "field": "color"
             },
             "aggs": {
                "avg_price": { 
                   "avg": {
                      "field": "price"
                   }
                },
                "make": { 
                    "terms": {
                        "field": "make" 
                    }
                }
             }
          }
       }
    }

<table style="border-collapse:collapse; border-spacing:0px; background-color:transparent; line-height:26px; color:rgb(68,68,68); font-size:15px; margin-bottom:1em; border:none; width:750px"> 
 <tbody style="line-height:26px; vertical-align:top"> 
  <tr style="line-height:26px"> 
   <td align="left" style="padding:0.75em 0.2em 0px; line-height:26px; font-size:15px; vertical-align:top; border-top:none; border-right:none; border-left:none; border-bottom:1px solid rgb(229,234,228)"> <p style="margin-top:0px; margin-bottom:10px; font-size:16px"><a href="https://www.elastic.co/guide/cn/elasticsearch/guide/current/_buckets_inside_buckets.html#CO188-1" style="background-color:transparent; color:rgb(0,169,229); outline:none" rel="nofollow"><span style="color:rgb(68,68,68)"><img src="https://www.elastic.co/guide/cn/elasticsearch/guide/current/images/icons/callouts/1.png" alt="" style="border:0px; vertical-align:middle"></span></a></p> </td> 
   <td align="left" style="padding:0.75em 0px 0px 0.2em; line-height:26px; font-size:15px; vertical-align:top; border-top:none; border-right:none; border-left:none; border-bottom:1px solid rgb(229,234,228)"> <p style="margin-top:0px; margin-bottom:10px; font-size:16px">注意前例中的&nbsp;<code style="font-family:Consolas,Menlo,&quot;DejaVu Sans Mono&quot;,&quot;Bitstream Vera Sans Mono&quot;,&quot;Lucida Console&quot;; font-size:0.9em; padding:0px 3px; color:rgb(85,85,85); background:rgb(248,248,248); display:inline; word-wrap:break-word; width:auto; overflow-x:auto; vertical-align:middle">avg_price</code>&nbsp;度量仍然保持原位。</p> </td> 
  </tr> 
  <tr style="line-height:26px"> 
   <td align="left" style="padding:0.75em 0.2em 0px; line-height:26px; font-size:15px; vertical-align:top; border-top:none; border-right:none; border-left:none; border-bottom:1px solid rgb(229,234,228)"> <p style="margin-top:0px; margin-bottom:10px; font-size:16px"><a href="https://www.elastic.co/guide/cn/elasticsearch/guide/current/_buckets_inside_buckets.html#CO188-2" style="background-color:transparent; color:rgb(0,169,229); outline:none" rel="nofollow"><span style="color:rgb(68,68,68)"><img src="https://www.elastic.co/guide/cn/elasticsearch/guide/current/images/icons/callouts/2.png" alt="" style="border:0px; vertical-align:middle"></span></a></p> </td> 
   <td align="left" style="padding:0.75em 0px 0px 0.2em; line-height:26px; font-size:15px; vertical-align:top; border-top:none; border-right:none; border-left:none; border-bottom:1px solid rgb(229,234,228)"> <p style="margin-top:0px; margin-bottom:10px; font-size:16px">另一个聚合&nbsp;<code style="font-family:Consolas,Menlo,&quot;DejaVu Sans Mono&quot;,&quot;Bitstream Vera Sans Mono&quot;,&quot;Lucida Console&quot;; font-size:0.9em; padding:0px 3px; color:rgb(85,85,85); background:rgb(248,248,248); display:inline; word-wrap:break-word; width:auto; overflow-x:auto; vertical-align:middle">make</code>&nbsp;被加入到了&nbsp;<code style="font-family:Consolas,Menlo,&quot;DejaVu Sans Mono&quot;,&quot;Bitstream Vera Sans Mono&quot;,&quot;Lucida Console&quot;; font-size:0.9em; padding:0px 3px; color:rgb(85,85,85); background:rgb(248,248,248); display:inline; word-wrap:break-word; width:auto; overflow-x:auto; vertical-align:middle">color</code>&nbsp;颜色桶中。</p> </td> 
  </tr> 
  <tr style="line-height:26px"> 
   <td align="left" style="padding:0.75em 0.2em 0px; line-height:26px; font-size:15px; vertical-align:top; border:none"> <p style="margin-top:0px; margin-bottom:10px; font-size:16px"><a href="https://www.elastic.co/guide/cn/elasticsearch/guide/current/_buckets_inside_buckets.html#CO188-3" style="background-color:transparent; color:rgb(0,169,229); outline:none" rel="nofollow"><span style="color:rgb(68,68,68)"><img src="https://www.elastic.co/guide/cn/elasticsearch/guide/current/images/icons/callouts/3.png" alt="" style="border:0px; vertical-align:middle"></span></a></p> </td> 
   <td align="left" style="padding:0.75em 0px 0px 0.2em; line-height:26px; font-size:15px; vertical-align:top; border:none"> <p style="margin-top:0px; margin-bottom:10px; font-size:16px">这个聚合是&nbsp;<code style="font-family:Consolas,Menlo,&quot;DejaVu Sans Mono&quot;,&quot;Bitstream Vera Sans Mono&quot;,&quot;Lucida Console&quot;; font-size:0.9em; padding:0px 3px; color:rgb(85,85,85); background:rgb(248,248,248); display:inline; word-wrap:break-word; width:auto; overflow-x:auto; vertical-align:middle">terms</code>&nbsp;桶，它会为每个汽车制造商生成唯一的桶。</p> </td> 
  </tr> 
 </tbody> 
</table>

这里发生了一些有趣的事。 首先，我们可能会观察到之前例子中的 `avg_price` 度量完全没有变化，还在原来的位置。 一个聚合的每个 层级 都可以有多个度量或桶， `avg_price` 度量告诉我们每种颜色汽车的平均价格。它与其他的桶和度量相互独立。

这对我们的应用非常重要，因为这里面有很多相互关联，但又完全不同的度量需要收集。聚合使我们能够用一次数据请求获得所有的这些信息。

另外一件值得注意的重要事情是我们新增的这个 `make` 聚合，它是一个 `terms` 桶（嵌套在 `colors` 、 `terms` 桶内）。这意味着它 会为数据集中的每个唯一组合生成（ `color` 、 `make` ）元组。

让我们看看返回的响应（为了简单我们只显示部分结果）：

{
    ...
       "aggregations": {
          "colors": {
             "buckets": [
                {
                   "key": "red",
                   "doc_count": 4,
                   "make": { 
                      "buckets": [
                         {
                            "key": "honda", 
                            "doc_count": 3
                         },
                         {
                            "key": "bmw",
                            "doc_count": 1
                         }
                      ]
                   },
                   "avg_price": {
                      "value": 32500 
                   }
                },
    
    ...
    }

<table style="border-collapse:collapse; border-spacing:0px; background-color:transparent; line-height:26px; color:rgb(68,68,68); font-size:15px; margin-bottom:1em; border:none; width:750px"> 
 <tbody style="line-height:26px; vertical-align:top"> 
  <tr style="line-height:26px"> 
   <td align="left" style="padding:0.75em 0.2em 0px; line-height:26px; font-size:15px; vertical-align:top; border-top:none; border-right:none; border-left:none; border-bottom:1px solid rgb(229,234,228)"> <p style="margin-top:0px; margin-bottom:10px; font-size:16px"><a href="https://www.elastic.co/guide/cn/elasticsearch/guide/current/_buckets_inside_buckets.html#CO189-1" style="background-color:transparent; color:rgb(0,169,229); outline:none" rel="nofollow"><span style="color:rgb(68,68,68)"><img src="https://www.elastic.co/guide/cn/elasticsearch/guide/current/images/icons/callouts/1.png" alt="" style="border:0px; vertical-align:middle"></span></a></p> </td> 
   <td align="left" style="padding:0.75em 0px 0px 0.2em; line-height:26px; font-size:15px; vertical-align:top; border-top:none; border-right:none; border-left:none; border-bottom:1px solid rgb(229,234,228)"> <p style="margin-top:0px; margin-bottom:10px; font-size:16px">正如期望的那样，新的聚合嵌入在每个颜色桶中。</p> </td> 
  </tr> 
  <tr style="line-height:26px"> 
   <td align="left" style="padding:0.75em 0.2em 0px; line-height:26px; font-size:15px; vertical-align:top; border-top:none; border-right:none; border-left:none; border-bottom:1px solid rgb(229,234,228)"> <p style="margin-top:0px; margin-bottom:10px; font-size:16px"><a href="https://www.elastic.co/guide/cn/elasticsearch/guide/current/_buckets_inside_buckets.html#CO189-2" style="background-color:transparent; color:rgb(0,169,229); outline:none" rel="nofollow"><span style="color:rgb(68,68,68)"><img src="https://www.elastic.co/guide/cn/elasticsearch/guide/current/images/icons/callouts/2.png" alt="" style="border:0px; vertical-align:middle"></span></a></p> </td> 
   <td align="left" style="padding:0.75em 0px 0px 0.2em; line-height:26px; font-size:15px; vertical-align:top; border-top:none; border-right:none; border-left:none; border-bottom:1px solid rgb(229,234,228)"> <p style="margin-top:0px; margin-bottom:10px; font-size:16px">现在我们看见按不同制造商分解的每种颜色下车辆信息。</p> </td> 
  </tr> 
  <tr style="line-height:26px"> 
   <td align="left" style="padding:0.75em 0.2em 0px; line-height:26px; font-size:15px; vertical-align:top; border:none"> <p style="margin-top:0px; margin-bottom:10px; font-size:16px"><a href="https://www.elastic.co/guide/cn/elasticsearch/guide/current/_buckets_inside_buckets.html#CO189-3" style="background-color:transparent; color:rgb(0,169,229); outline:none" rel="nofollow"><span style="color:rgb(68,68,68)"><img src="https://www.elastic.co/guide/cn/elasticsearch/guide/current/images/icons/callouts/3.png" alt="" style="border:0px; vertical-align:middle"></span></a></p> </td> 
   <td align="left" style="padding:0.75em 0px 0px 0.2em; line-height:26px; font-size:15px; vertical-align:top; border:none"> <p style="margin-top:0px; margin-bottom:10px; font-size:16px">最终，我们看到前例中的&nbsp;<code style="font-family:Consolas,Menlo,&quot;DejaVu Sans Mono&quot;,&quot;Bitstream Vera Sans Mono&quot;,&quot;Lucida Console&quot;; font-size:0.9em; padding:0px 3px; color:rgb(85,85,85); background:rgb(248,248,248); display:inline; word-wrap:break-word; width:auto; overflow-x:auto; vertical-align:middle">avg_price</code>&nbsp;度量仍然维持不变。</p> </td> 
  </tr> 
 </tbody> 
</table>

响应结果告诉我们以下几点：

*  红色车有四辆。
 *  红色车的平均售价是 $32，500 美元。
 *  其中三辆是 Honda 本田制造，一辆是 BMW 宝马制造。

Java代码实现：

/**
         * Description:桶嵌套
         * 例：计算每个颜色的汽车制造商的分布
         * https://www.elastic.co/guide/cn/elasticsearch/guide/current/_buckets_inside_buckets.html
         * @author wangweidong
         * CreateTime: 2017年11月9日 下午3:47:54
        */
       @Test
       public void bucketsMetricsAggregation2() {
    	   String index = "cars";
    	   String type = "transactions";
    	   SearchRequestBuilder searchRequestBuilder = client.prepareSearch(index).setTypes(type);
       	
    	   //颜色
           TermsAggregationBuilder colorsField = AggregationBuilders.terms("popular_colors").field("color.keyword");
           
           //平均价格
           AvgAggregationBuilder avgPriceField = AggregationBuilders.avg("avg_price").field("price");
           colorsField.subAggregation(avgPriceField);
           
           //制造商
           TermsAggregationBuilder makeField = AggregationBuilders.terms("make").field("make.keyword");
           colorsField.subAggregation(makeField);
           
           searchRequestBuilder.addAggregation(colorsField);
           searchRequestBuilder.setSize(0);
           SearchResponse searchResponse = searchRequestBuilder.execute().actionGet();
           
           System.out.println(searchResponse.toString());
           
           Terms genders = searchResponse.getAggregations().get("popular_colors");
    	   for (Terms.Bucket entry : genders.getBuckets()) {
    		   Object colorName = entry.getKey();      // Term
    	       Long colorCount = entry.getDocCount(); // Doc count
    	       
    	       Aggregations agg = entry.getAggregations();
    	       Avg avg = agg.get("avg_price");
    	       Double avgPrice = avg.getValue();
    	       
    	       String info = "其中";
    	       Terms makes = entry.getAggregations().get("make");
    	       for (Terms.Bucket makeEntry : makes.getBuckets()) {
    	    	   Object makeName = makeEntry.getKey();
    		       Long makeCount = makeEntry.getDocCount();
    		       info = info + makeCount + "辆是" + makeName + "制造，";
    	       }
    	        
    	       System.out.println(colorName + "车有" + colorCount + "辆，平均每台车价格：" + avgPrice + "，" + info);
    	   }
       }

文章参考： [https://www.elastic.co/guide/cn/elasticsearch/guide/current/\_buckets\_inside\_buckets.html][https_www.elastic.co_guide_cn_elasticsearch_guide_current_buckets_inside_buckets.html]

[Link 1]: https://github.com/elasticsearch-cn/elasticsearch-definitive-guide/edit/cn/300_Aggregations/22_nested_bucket.asciidoc
[http_blog.csdn.net_wwd0501_article_details_78501842]: http://blog.csdn.net/wwd0501/article/details/78501842
[https_www.elastic.co_guide_cn_elasticsearch_guide_current_buckets_inside_buckets.html]: https://www.elastic.co/guide/cn/elasticsearch/guide/current/_buckets_inside_buckets.html