使用聚合過濾器的術語聚合返回比不使用聚合過濾器更多的doc_count

Question

我將一些數據作爲嵌套對象存儲在ElasticSearch中，但聚合結果對我來說沒有意義。不知道爲什麼當應用聚合過濾器時，我會在doc_count中有更多的嵌套對象。爲with aggregation filter

|      | terms w.o. | terms with | 
|      | agg filter | agg filter | 
|------------------------|-----------:|-----------:| 
| total documents  | 41,690,696 | 41,690,696 | 
| nested object   | 77,999,324 | 77,999,324 | 
| filtered nested object | 77,999,324 |  89,116 | 
| agg "ITEM 1"   |  87,905 |  89,116 | 
| reversed agg   |  19,976 |  20,499 | 

查詢有效載荷如下所示並取出必須的部分將成爲without aggregation filter查詢。

{ 
    "from": 0, 
    "size": 0, 
    "aggregations": { 
    "requestedDimension": { 
     "nested": { 
     "path": "NESTED_PATH" 
     }, 
     "aggregations": { 
     "requestedDimension": { 
      "filter": { 
      "bool": { 
       "must": [ // query for without filter will remove this must 
       { 
        "terms": { 
        "NESTED_PATH.PROP": [ 
         "ITEM_1" 
        ] 
        } 
       } 
       ], 
       "disable_coord": false, 
       "adjust_pure_negative": true 
      } 
      }, 
      "aggregations": { 
      "requestedDimension": { 
       "terms": { 
       "field": "NESTED_PATH.PROP1", 
       "size": 10 
       }, 
       "aggregations": { 
       "userCount": { 
        "reverse_nested": {} 
       } 
       } 
      } 
      } 
     } 
     } 
    } 
    } 
} 

Answer 1

原來這是因爲聚合條款是近似 https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket-terms-aggregation.html#search-aggregations-bucket-terms-aggregation-approximate-counts

即PROP是高基數屬性，因此整體頂部10元件可以不是頂部在每個碎片10個元素。當我應用過濾器聚合時，它會過濾除前十個元素以外的所有元素，因此它確保所有前十個元素都被計數。