elasticsearch - 如何使 Elasticsearch 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"}}
      ]
    }
  }
}

期望在结果中得到如下顺序:

1)“音乐节”

2)“音乐节舞会”

3)“音乐节电子舞曲”

4)“德国电子音乐节舞蹈”

5)“音乐”

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"
                        }
                    ]
                }
            }
        ]
    }
}

除了只匹配一个单词的最低分数外，其顺序似乎完全随机。

可能是什么原因导致的，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 个词条目作为第一个结果，因此使用或提升词条查询似乎是不可能的。

Answer 1

正如我在 this answer 中所描述的那样评分/相关性不是 Elasticsearch 中最简单的主题。

我正试图为您找出解决方案，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 }

和查询:

{
  "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，它适用于 ["music", "festival"] 和 ["music", "dance"](在 ES 6.2 上测试过)，但我猜测在其他结果上它不会像您预期的那样 100% 起作用。主要是因为相关性/评分的复杂性。但您现在可以阅读更多关于我使用的东西并尝试改进它。