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Elasticsearch：运用 distance feature 查询来增强相关性

程序员文章站 2022-07-05 13:21:43
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提高文档的相关性得分，使其更接近提供的原始日期或地点。 例如，您可以使用此查询为更接近某个日期或位置的文档赋予更大的权重。

您可以使用distance_feature查询查找与某个位置最近的邻居。 您还可以在布尔搜索的“should”过滤器中使用查询，以将增强的相关性得分添加到布尔查询的得分中。

下面我们用一个具体的例子来展示这个API的使用。

 

准备数据

我们还是拿之前我们的文章“Elasticsearch: 运用Field collapsing来减少基于单个字段的搜索结果”中的索引来做例子。在那个例子里，我们把数据导入到Elasticsearch中。我们可以查看一下它的mapping:

GET best_games/_mapping
{
  "best_games" : {
    "mappings" : {
      "_meta" : {
        "created_by" : "ml-file-data-visualizer"
      },
      "properties" : {
        "critic_score" : {
          "type" : "long"
        },
        "developer" : {
          "type" : "text"
        },
        "genre" : {
          "type" : "keyword"
        },
        "global_sales" : {
          "type" : "double"
        },
        "id" : {
          "type" : "keyword"
        },
        "image_url" : {
          "type" : "keyword"
        },
        "name" : {
          "type" : "text"
        },
        "platform" : {
          "type" : "keyword"
        },
        "publisher" : {
          "type" : "keyword"
        },
        "user_score" : {
          "type" : "long"
        },
        "year" : {
          "type" : "long"
        }
      }
    }
  }
}

我们从上面可以看出来，上面的year显示的是long类型的数据。显然这个不是我们所需要的。我们希望它是date类型的数据。我们需要重新对我们的数据进行reindex。对于不很熟悉reindex的开发者来说，你可以参照我之前的文章“Elasticsearch: Reindex接口”。

我们来重新定义一个新的叫做best_games的索引：

PUT best_games1
{
  "mappings": {
    "properties": {
      "critic_score": {
        "type": "long"
      },
      "developer": {
        "type": "text"
      },
      "genre": {
        "type": "keyword"
      },
      "global_sales": {
        "type": "double"
      },
      "id": {
        "type": "keyword"
      },
      "image_url": {
        "type": "keyword"
      },
      "name": {
        "type": "text"
      },
      "platform": {
        "type": "keyword"
      },
      "publisher": {
        "type": "keyword"
      },
      "user_score": {
        "type": "long"
      },
      "year": {
        "type": "date",
        "format": "strict_year"
      }
    }
  }
}

在上面的mapping里，我们重新定义了year为date类型。那么我们可以通过如下的命令来reindex我们的best_games1索引：

POST _reindex
{
  "source": {
    "index": "best_games"
  },
  "dest": {
    "index": "best_games1"
  }
}

操作完上面的命令后，我们可以重新查看一下我的best_games1索引的文档数量：

GET best_games1/_count

显示结果为：

{
  "count" : 500,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  }
}

这样我们在best_games1中已经存在我们想要的索引数据了。

distance_feature 查询

接下来，我们开始做一些查询。比如我们查询一下critical_score大于90的所有文档：

GET /best_games1/_search
{
  "query": {
    "bool": {
      "filter": {
        "range": {
          "critic_score": {
            "gte": 90
          }
        }
      }
    }
  }
}

显示的结果为：

    "hits" : [
      {
        "_index" : "best_games1",
        "_type" : "_doc",
        "_id" : "hnLfF28BjrINWI3xWOLh",
        "_score" : 0.0,
        "_source" : {
          "id" : "mario-kart-ds-ds-2005",
          "name" : "Mario Kart DS",
          "year" : 2005,
          "platform" : "DS",
          "genre" : "Racing",
          "publisher" : "Nintendo",
          "global_sales" : 23.21,
          "critic_score" : 91,
          "user_score" : 8,
          "developer" : "Nintendo",
          "image_url" : "https://upload.wikimedia.org/wikipedia/en/thumb/a/ad/Mario_Kart_DS_screenshot.png/220px-Mario_Kart_DS_screenshot.png"
        }
      },
      {
        "_index" : "best_games1",
        "_type" : "_doc",
        "_id" : "inLfF28BjrINWI3xWOLh",
        "_score" : 0.0,
        "_source" : {
          "id" : "grand-theft-auto-v-ps3-2013",
          "name" : "Grand Theft Auto V",
          "year" : 2013,
          "platform" : "PS3",
          "genre" : "Action",
          "publisher" : "Take-Two Interactive",
          "global_sales" : 21.04,
          "critic_score" : 97,
          "user_score" : 8,
          "developer" : "Rockstar North",
          "image_url" : "https://pmcvariety.files.wordpress.com/2013/09/gta-v-big.jpg?w=1000&h=563&crop=1"
        }
      },
      {
        "_index" : "best_games1",
        "_type" : "_doc",
        "_id" : "i3LfF28BjrINWI3xWOLh",
        "_score" : 0.0,
        "_source" : {
          "id" : "grand-theft-auto-san-andreas-ps2-2004",
          "name" : "Grand Theft Auto: San Andreas",
          "year" : 2004,
          "platform" : "PS2",
          "genre" : "Action",
          "publisher" : "Take-Two Interactive",
          "global_sales" : 20.81,
          "critic_score" : 95,
          "user_score" : 9,
          "developer" : "Rockstar North",
          "image_url" : "http://4.bp.blogspot.com/-IITyrVJdS50/Udvw7XLG-oI/AAAAAAAASwY/H1j2GYBjXng/s1600/GTA+SA+0.jpg"
        }
      },
 ...

显然这个结果里有一些文档的年代非常久远，可能并不是我们想要的结果。那么我改如何把那些靠近我们的年代的文档排名到前面呢？答案是使用distance_feature查询。

我们使用如下的方法来进行查询：

GET /best_games1/_search
{
  "query": {
    "bool": {
      "filter": {
        "range": {
          "critic_score": {
            "gte": 90
          }
        }
      },
      "should": {
        "distance_feature": {
          "field": "year",
          "pivot": "2555d",
          "origin": "now"
        }
      }
    }
  }
}

我们通过distance_feature的引入，上面定义了从现在开始到7年之间（2555天）所有文档的分数都将被提高，同时超过7年之上的文档都只享受一半的提高。那么这样的搜索的结果是：

    "hits" : [
      {
        "_index" : "best_games1",
        "_type" : "_doc",
        "_id" : "-XLfF28BjrINWI3xWOLi",
        "_score" : 0.63837445,
        "_source" : {
          "id" : "uncharted-4-a-thiefs-end-ps4-2016",
          "name" : "Uncharted 4: A Thief's End",
          "year" : 2016,
          "platform" : "PS4",
          "genre" : "Shooter",
          "publisher" : "Sony Computer Entertainment",
          "global_sales" : 5.38,
          "critic_score" : 93,
          "user_score" : 7,
          "developer" : "Naughty Dog",
          "image_url" : "https://i.ytimg.com/vi/hh5HV4iic1Y/maxresdefault.jpg"
        }
      },
      {
        "_index" : "best_games1",
        "_type" : "_doc",
        "_id" : "T3LfF28BjrINWI3xWOPi",
        "_score" : 0.5850225,
        "_source" : {
          "id" : "the-witcher-3-wild-hunt-ps4-2015",
          "name" : "The Witcher 3: Wild Hunt",
          "year" : 2015,
          "platform" : "PS4",
          "genre" : "Role-Playing",
          "publisher" : "Namco Bandai Games",
          "global_sales" : 3.97,
          "critic_score" : 92,
          "user_score" : 9,
          "developer" : "CD Projekt Red Studio",
          "image_url" : "https://www.godisageek.com/wp-content/uploads/the-witcher-3-monster-1024x576.jpg"
        }
      },
      {
        "_index" : "best_games1",
        "_type" : "_doc",
        "_id" : "inLfF28BjrINWI3xWOPi",
        "_score" : 0.5850225,
        "_source" : {
          "id" : "metal-gear-solid-v-the-phantom-pain-ps4-2015",
          "name" : "Metal Gear Solid V: The Phantom Pain",
          "year" : 2015,
          "platform" : "PS4",
          "genre" : "Action",
          "publisher" : "Konami Digital Entertainment",
          "global_sales" : 3.41,
          "critic_score" : 93,
          "user_score" : 8,
          "developer" : "Kojima Productions, Moby Dick Studio",
          "image_url" : "https://i.ytimg.com/vi/gtgNUFSoHv8/maxresdefault.jpg"
        }
      },
  ...

从上面的显示结果可以看出来，靠近最近年份的文档最先出现，而且得分较高。

同样地，我们也可以基于位置对文档进行提高。以下布尔搜索将返回名称为chocolate的文档。 该搜索还使用distance_feature查询来增加位置值接近[-71.3，41.15]的文档的相关性得分。

GET /items/_search
{
  "query": {
    "bool": {
      "must": {
        "match": {
          "name": "chocolate"
        }
      },
      "should": {
        "distance_feature": {
          "field": "location",
          "pivot": "1000m",
          "origin": [-71.3, 41.15]
        }
      }
    }
  }
}

 

参考：

【1】https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-distance-feature-query.html

相关标签： Elastic

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