如何使弹性搜索评分考虑字段长度

Question

我创建了一个非常简单的测试索引，包含以下 5 个条目：

{    "tags": [        { "topics": "music festival dance techno germany"}    ]}
{    "tags": [        { "topics": "music festival dance techno"}    ]}
{    "tags": [        { "topics": "music festival dance"}    ]}
{    "tags": [        { "topics": "music festival"}    ]}
{    "tags": [        { "topics": "music"}    ]}

然后我执行了以下查询：

{
  "query": { 
    "bool": { 
      "should": [
        { "match": { "tags.topics": "music festival"}}
      ]
    }
  }
}

期望在结果中获得以下顺序：

1) "music festival"

2) "music festival dance"

3) "music festival dance techno"

4) "music festival dance techno germany"

5) "music"

考虑字段长度规范化。

但是我得到了以下信息：

{
    "took": 4,
    "timed_out": false,
    "_shards": {
        "total": 5,
        "successful": 5,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": 5,
        "max_score": 0.5753642,
        "hits": [
            {
                "_index": "testindex",
                "_type": "entry",
                "_id": "1",
                "_score": 0.5753642,
                "_source": {
                    "tags": [
                        {
                            "topics": "music festival dance techno germany"
                        }
                    ]
                }
            },
            {
                "_index": "testindex",
                "_type": "entry",
                "_id": "3",
                "_score": 0.5753642,
                "_source": {
                    "tags": [
                        {
                            "topics": "music festival dance"
                        }
                    ]
                }
            },
            {
                "_index": "testindex",
                "_type": "entry",
                "_id": "4",
                "_score": 0.42221835,
                "_source": {
                    "tags": [
                        {
                            "topics": "music festival"
                        }
                    ]
                }
            },
            {
                "_index": "testindex",
                "_type": "entry",
                "_id": "2",
                "_score": 0.32088596,
                "_source": {
                    "tags": [
                        {
                            "topics": "music festival dance techno"
                        }
                    ]
                }
            },
            {
                "_index": "testindex",
                "_type": "entry",
                "_id": "5",
                "_score": 0.2876821,
                "_source": {
                    "tags": [
                        {
                            "topics": "music"
                        }
                    ]
                }
            }
        ]
    }
}

他的顺序看起来完全随机，除了最低分数只匹配一个词。

是什么原因导致的，我可以更改什么（在映射、索引或搜索期间）以获得预期的顺序？

注意：非完美匹配查询也是如此。搜索 "music dance" 应该仍会产生 3 个词的条目作为第一个结果，因此使用或提升术语查询似乎是不可能的。

Answer 1

正如我在中所描述的那样 scoring/relevance 并不是 Elasticsearch 中最简单的主题。

我正在尝试为您找出解决方案，目前我有类似的解决方案。

文件：

{ "tags": [ { "topics": ["music", "festival", "dance", "techno", "germany"]} ], "topics_count": 5 }
{ "tags": [ { "topics": ["music", "festival", "dance", "techno"]} ], "topics_count": 4 }
{ "tags": [ { "topics": ["music", "festival", "dance"] } ], "topics_count": 3 }
{ "tags": [ { "topics": ["music", "festival"]} ], "topics_count": 2 }
{ "tags": [ { "topics": ["music"]} ], "topics_count": 1 }

并查询：

{
  "query": {
    "bool": {
      "should": [
        {
          "function_score": {
            "query": {
              "terms_set": {
                "tags.topics" : {
                  "terms" : ["music", "festival"],
                  "minimum_should_match_script": {
                    "source": "params.num_terms"
                  }
                }
              }
            },
            "script_score" : {
              "script" : {
                "source": "_score * Math.sqrt(1.0 / doc['topics_count'].value)"
              }
            }
          }
        },
        {
          "function_score": {
            "query": {
              "terms_set": {
                "tags.topics" : {
                 "terms" : ["music", "festival"],
                 "minimum_should_match_script": {
                    "source": "doc['topics_count'].value"
                  }
                }
              }
            },
            "script_score" : {
              "script" : {
                "source": "_score * Math.sqrt(1.0 / doc['topics_count'].value)"
              }
            }
          }
        }
      ]
    }
  }
}

它并不完美。仍然需要一些改进。在这个例子中，它对于 ["music", "festival"] 和 ["music", "dance"] 运行良好（在 ES 6.2 上测试），但我猜测在其他结果上它不会像您预期的那样 100% 运行。主要是因为 relevance/scoring 的复杂性。但是你现在可以阅读更多关于我使用的东西并尝试改进它。

如何使弹性搜索评分考虑字段长度

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