Elasticsearch aggregation with hierarchical category, subcategory; limit the levels

问题

I have products with categories field. Using the aggregation I can get the full categories with all subcategories. I want to limit the levels in the facet.

e.g. I have the facets like:

auto, tools & travel    (115)
auto, tools & travel > luggage tags (90)
auto, tools & travel > luggage tags > luggage spotters  (40)
auto, tools & travel > luggage tags > something else    (50)
auto, tools & travel > car organizers   (25)

Using aggregation like

"aggs": {
    "cat_groups": {
      "terms": {
        "field": "categories.keyword",
        "size": 10,
       "include": "auto, tools & travel > .*"
      }
    }
}

I am getting buckets like

"buckets": [
        {
          "auto, tools & travel > luggage tags",
          "doc_count": 90
        },
        {
          "key": "auto, tools & travel > luggage tags > luggage spotters",
          "doc_count": 40
        },
        {
          "key": "auto, tools & travel > luggage tags > something else",
          "doc_count": 50
        },
        {
          "key": "auto, tools & travel > car organizers",
          "doc_count": 25
        }
]

But I want to limit the level. e.g. I want to get only the results for auto, tools & travel > luggage tags. How can I limit the levels? By the way, "exclude": ".* > .* > .*" does not work for me.

I need to get buckets for different levels according to search. Sometimes first level, and sometimes second or third. When I want first level, I don't want the second levels to appear on buckets; and so on for other levels.

Elasticsearch version 6.4

回答1:

Finally I've been able to figure the below technique.

I have implemented a custom analyzer using Path Hierarchy Tokenizer and I have created multi-field called categories so that you can use categories.facets for aggregations/facets and do normal text search using categories.

The custom analyzer would only apply for categories.facets

Do note the property "fielddata": "true" for my field categories.facet

Mapping

PUT myindex
{
  "settings": {
    "analysis": {
      "analyzer": {
        "my_analyzer": {
          "tokenizer": "my_tokenizer"
        }
      },
      "tokenizer": {
        "my_tokenizer": {
          "type": "path_hierarchy",
          "delimiter": ">"
        }
      }
    }
  },
  "mappings": {
    "mydocs": {
      "properties": {
        "categories": {
          "type": "text",
          "fields": {
            "facet": { 
              "type":  "text",
              "analyzer": "my_analyzer",
              "fielddata": "true"
            }
          }
        }
      }
    }
  }
}

Sample Documents

POST myindex/mydocs/1
{
    "categories" : "auto, tools & travel > luggage tags > luggage spotters"
}

POST myindex/mydocs/2
{
    "categories" : "auto, tools & travel > luggage tags > luggage spotters"
}

POST myindex/mydocs/3
{
    "categories" : "auto, tools & travel > luggage tags > luggage spotters"
}

POST myindex/mydocs/4
{
    "categories" : "auto, tools & travel > luggage tags > something else"
}

Query

You can try the below query which you are looking for. Again I've implemented Filter Aggregation because you need only specific words along with Terms Aggregation.

{
  "size": 0,
  "aggs":{
    "facets": {
      "filter": { 
          "bool": {
            "must": [
              { "match": { "categories": "luggage"} }
            ]
         }
      },
      "aggs": {
        "categories": {
          "terms": {
            "field": "categories.facet"
          }
        }
      }
    }
  }
}

Response

{
    "took": 43,
    "timed_out": false,
    "_shards": {
        "total": 1,
        "successful": 1,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": 11,
        "max_score": 0,
        "hits": []
    },
    "aggregations": {
        "facets": {
            "doc_count": 4,
            "categories": {
                "doc_count_error_upper_bound": 0,
                "sum_other_doc_count": 0,
                "buckets": [
                    {
                        "key": "auto, tools & travel ",
                        "doc_count": 4
                    },
                    {
                        "key": "auto, tools & travel > luggage tags ",
                        "doc_count": 4
                    },
                    {
                        "key": "auto, tools & travel > luggage tags > luggage spotters",
                        "doc_count": 3
                    },
                    {
                        "key": "auto, tools & travel > luggage tags > something else",
                        "doc_count": 1
                    }
                ]
            }
        }
    }
}

Final Answer Post Discussion On Chat

POST myindex/_search
{
  "size": 0,
  "aggs":{
    "facets": {
      "filter": { 
          "bool": {
            "must": [
              { "match": { "categories": "luggage"} }
          ]
        }
      },
      "aggs": {
        "categories": {
          "terms": {
            "field": "categories.facet",
            "exclude": ".*>{1}.*>{1}.*"
          }
        }
      }
    }
  }
}

Note that I've added exclude with a regular expression in such a way that it would not consider any facets which is having more than one occurrence of >

Let me know this if it helps.

回答2:

Just add an integer field named level signifying your category's level in the hierarchy. Just count the number of occurrence of your delimiter '>' and save it as the value. Then add a rangeQuery to your boolQuery.

Add this to your schema:

"level": {
    "type": "integer",
    "store": "true",
    "index": "true"
}

In your code you have something like this which counts the number of delimiter suggesting the level of hierarchy (no delimiter means main category):

public Builder(final String path) {
    this.path = path;
    this.level = StringUtils.countMatches(path, DELIMITER);
}

and then your query search could have something like:

{
    "query": {
        "bool": {
            "filter": [
                {
                    "prefix": {
                        "category": {
                            "value": "auto, tools & travel",
                            "boost": 1
                        }
                    }
                },
                {
                    "range": {
                        "level": {
                            "from": 2,
                            "to": 4,
                            "include_lower": true,
                            "include_upper": true,
                            "boost": 1
                        }
                    }
                }
            ],
            "adjust_pure_negative": true,
            "boost": 1
        }
    }
}

来源：https://stackoverflow.com/questions/52940790/elasticsearch-aggregation-with-hierarchical-category-subcategory-limit-the-lev