# Query can return negative score? I couldn't find any spec on documentation. The minimum value of score is not 0?

**URL:** <https://discuss.elastic.co/t/query-can-return-negative-score-i-couldnt-find-any-spec-on-documentation-the-minimum-value-of-score-is-not-0/191307>\
**Category:** Elasticsearch\
**Created:** [July 19, 2019, 3:43am UTC](https://discuss.elastic.co/t/query-can-return-negative-score-i-couldnt-find-any-spec-on-documentation-the-minimum-value-of-score-is-not-0/191307 "2019-07-19T03:43:23Z")\
**Posts on this page:** 10\
**Page:** 1

<div class="post-metadata">

**Author:** ![hangu\_choi](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/hangu_choi/32/49745_2.png) [@hangu\_choi](https://discuss.elastic.co/u/hangu_choi)\
**Post date:** [July 19, 2019, 3:43am UTC](https://discuss.elastic.co/t/query-can-return-negative-score-i-couldnt-find-any-spec-on-documentation-the-minimum-value-of-score-is-not-0/191307/1 "2019-07-19T03:43:23Z")

</div>

I got some negative score for document `-1.0910728`

I didn't expect this, query can return negative score?  
Should I use `min_score`? or is this just a bug?

- Update: `min_score` seems not helped, because I want use function score, and function\_score seems calculate score before min\_score.

and the negative scored document has matched keyword, and have highlights also!

below is the query I used.

```auto
{
  "query": {
    "function_score": {
      "query": {
        "bool": {
          "must": [
            {
              "multi_match": {
                "query": "hello",
                "type": "cross_fields",
                "fields": [
                  "introduction.text^3",
                     ......                  
                ],
                "slop": 10
              }
            }
          ],
          "filter": [
            {
              "range": {
                "age": {
                  "gte": 1
                }
              }
            },
            {
              "range": {
                "age": {
                  "lte": 1
                }
              }
            }
          ]
        }
      },
      "boost": 5,
      "score_mode": "multiply",
      "boost_mode": "multiply",
      "functions": []
    }
  },
  "from": 0,
  "size": 30,
  "sort": [
    "_score"
  ]
}

```

---

<div class="post-metadata">

**Author:** ![dadoonet](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/dadoonet/32/137187_2.png) [@dadoonet](https://discuss.elastic.co/u/dadoonet)\
**Post date:** [July 19, 2019, 6:34am UTC](https://discuss.elastic.co/t/query-can-return-negative-score-i-couldnt-find-any-spec-on-documentation-the-minimum-value-of-score-is-not-0/191307/2 "2019-07-19T06:34:50Z")

</div>

Could you provide a full recreation script as described in [About the Elasticsearch category](https://discuss.elastic.co/t/about-the-elasticsearch-category/21). It will help to better understand what you are doing. Please, try to keep the example as simple as possible.

A full reproduction script will help readers to understand, reproduce and if needed fix your problem. It will also most likely help to get a faster answer.

---

<div class="post-metadata">

**Author:** ![hangu\_choi](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/hangu_choi/32/49745_2.png) [@hangu\_choi](https://discuss.elastic.co/u/hangu_choi)\
**Post date:** [July 19, 2019, 2:13pm UTC](https://discuss.elastic.co/t/query-can-return-negative-score-i-couldnt-find-any-spec-on-documentation-the-minimum-value-of-score-is-not-0/191307/3 "2019-07-19T14:13:43Z")

</div>

@dadoonet,  
Thank you for your reply.

If I could, I would provide recreation script so that others can reproduce.  
but in this case, I'm having hard time to reproduce the error.  
I got the negative score, but how can I reproduce the negative score problem is different thing, I think.

I will update if I find `the script`. but until now, I didn't. and I'm trying.

By the way, Do you know the rule for score?  
I thought score's minimum value is zero. but am I wrong?

I would be glad if I know the negative score is bug or not regardless of finding how reproduce the problem.

Thank you!

---

<div class="post-metadata">

**Author:** ![dadoonet](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/dadoonet/32/137187_2.png) [@dadoonet](https://discuss.elastic.co/u/dadoonet)\
**Post date:** [July 19, 2019, 2:16pm UTC](https://discuss.elastic.co/t/query-can-return-negative-score-i-couldnt-find-any-spec-on-documentation-the-minimum-value-of-score-is-not-0/191307/4 "2019-07-19T14:16:14Z")

</div>

What do you have with `"explain": true`?

---

<div class="post-metadata">

**Author:** ![hangu\_choi](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/hangu_choi/32/49745_2.png) [@hangu\_choi](https://discuss.elastic.co/u/hangu_choi)\
**Post date:** [July 19, 2019, 2:31pm UTC](https://discuss.elastic.co/t/query-can-return-negative-score-i-couldnt-find-any-spec-on-documentation-the-minimum-value-of-score-is-not-0/191307/5 "2019-07-19T14:31:33Z")

</div>

@dadoonet,

ah, I forgot the `explain: true`.  
Thank you for remind me. This is what I got with `explain: true`

```auto
        "_explanation": {
          "value": -16.503696,
          "description": "sum of:",
          "details": [
            {
              "value": 0,
              "description": "max of:",
              "details": [
                {
                  "value": -16.503696,
                  "description": "weight(profile.occupation_name:개발 in 0) [PerFieldSimilarity], result of:",
                  "details": [
                    {
                      "value": -16.503696,
                      "description": "score(freq=1.0), product of:",
                      "details": [
                        {
                          "value": 55,
                          "description": "boost",
                          "details": []
                        },
                        {
                          "value": -0.6061358,
                          "description": "idf, computed as log(1 + (N - n + 0.5) / (n + 0.5)) from:",
                          "details": [
                            {
                              "value": 5,
                              "description": "n, number of documents containing term",
                              "details": []
                            },
                            {
                              "value": 2,
                              "description": "N, total number of documents with field",
                              "details": []
                            }
                          ]
                        },
                        {
                          "value": 0.49504948,
                          "description": "tf, computed as freq / (freq + k1 * (1 - b + b * dl / avgdl)) from:",
                          "details": [
                            {
                              "value": 1,
                              "description": "freq, occurrences of term within document",
                              "details": []
                            },
                            {
                              "value": 1.2,
                              "description": "k1, term saturation parameter",
                              "details": []
                            },
                            {
                              "value": 0.75,
                              "description": "b, length normalization parameter",
                              "details": []
                            },
                            {
                              "value": 2,
                              "description": "dl, length of field",
                              "details": []
                            },
                            {
                              "value": 2.5,
                              "description": "avgdl, average length of field",
                              "details": []
                            }
                          ]
                        }
                      ]
                    }
                  ]
                }
              ]
            },
            {
              "value": 0,
              "description": "match on required clause, product of:",
              "details": [
                {
                  "value": 0,
                  "description": "# clause",
                  "details": []
                },
                {
                  "value": 1,
                  "description": "profile.tos_service:T",
                  "details": []
                }
              ]
            }
          ]
        }
      }
    

```

---

<div class="post-metadata">

**Author:** ![dadoonet](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/dadoonet/32/137187_2.png) [@dadoonet](https://discuss.elastic.co/u/dadoonet)\
**Post date:** [July 19, 2019, 3:08pm UTC](https://discuss.elastic.co/t/query-can-return-negative-score-i-couldnt-find-any-spec-on-documentation-the-minimum-value-of-score-is-not-0/191307/6 "2019-07-19T15:08:24Z")

</div>

@jpountz Do you know why this is happening?

---

<div class="post-metadata">

**Author:** ![hangu\_choi](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/hangu_choi/32/49745_2.png) [@hangu\_choi](https://discuss.elastic.co/u/hangu_choi)\
**Post date:** [July 22, 2019, 1:07am UTC](https://discuss.elastic.co/t/query-can-return-negative-score-i-couldnt-find-any-spec-on-documentation-the-minimum-value-of-score-is-not-0/191307/8 "2019-07-22T01:07:06Z")

</div>

I can reproduce this situation with below script.  
maybe the problem could be `n` is bigger than `N`  
@dadoonet

```auto
curl -X DELETE "localhost:9700/some_index"

curl -X PUT "localhost:9700/some_index" -H 'Content-Type: application/json' -d'
{
  "settings": {
    "number_of_shards": 5,
    "number_of_replicas": 1
  },
  "mappings": {
    "dynamic": false,
    "properties": {
      "user_id": {
        "type": "integer"
      },
      "introduction": {
        "type": "text"
      },
      "occupation_name": {
        "type": "text", 
        "fields": {
          "standard": { "type": "text" },  
          "raw": { "type": "keyword" }     
        }
      }
    }
  }
}
'

```

```auto

curl -X PUT "localhost:9700/some_index/_doc/1" -H "Content-Type: application/json" -d'
{
  "user_id": 1,
  "introduction": "ruby web developer"
}
'

curl -X PUT "localhost:9700/some_index/_doc/2" -H "Content-Type: application/json" -d'
{
  "user_id": 2,
  "introduction": "ruby developer",
  "occupation_name": "ruby developer"
}
'

curl -X PUT "localhost:9700/some_index/_doc/3" -H "Content-Type: application/json" -d'
{
  "user_id": 3,
  "introduction": "ruby and rails develop"
}
'

curl -X PUT "localhost:9700/some_index/_doc/4" -H "Content-Type: application/json" -d'
{
  "user_id": 4,
  "introduction": "I develop with ruby on rails"
}
'

curl -X PUT "localhost:9700/some_index/_doc/5" -H "Content-Type: application/json" -d'
{
  "user_id": 5,
  "introduction": "I develop with ruby on rails"
}
'

curl -X PUT "localhost:9700/some_index/_doc/6" -H "Content-Type: application/json" -d'
{
  "user_id": 6,
  "introduction": "I develop with ruby on rails"
}
'

curl -X PUT "localhost:9700/some_index/_doc/7" -H "Content-Type: application/json" -d'
{
  "user_id": 7,
  "introduction": "I develop with ruby on rails"
}
'

curl -X PUT "localhost:9700/some_index/_doc/8" -H "Content-Type: application/json" -d'
{
  "user_id": 8,
  "introduction": "I develop with ruby on rails"
}
'

curl -X PUT "localhost:9700/some_index/_doc/9" -H "Content-Type: application/json" -d'
{
  "user_id": 9,
  "introduction": "I develop with ruby on rails"
}
'

curl -X PUT "localhost:9700/some_index/_doc/10" -H "Content-Type: application/json" -d'
{
  "user_id": 10,
  "introduction": "I develop with ruby on rails"
}
'

curl -X PUT "localhost:9700/some_index/_doc/11" -H "Content-Type: application/json" -d'
{
  "user_id": 11,
  "introduction": "I develop with ruby on rails"
}
'

```

and query

```auto

curl -X GET "localhost:9700/some_index/_search" -H 'Content-Type: application/json' -d'
{
  "query": {
    "function_score": {
      "query": {
        "bool": {
          "must": [
            {
              "multi_match": {
                "query": "ruby",
                "type": "cross_fields",
                "fields": [
                  "occupation_name^5",
                  "introduction^2"                  
                ],
                "slop": 10
              }
            }
          ]
        }
      },
      "functions": []
    }
  },
  "from": 0,
  "size": 10,
  "explain": true
}
'

```

the response:

```auto
...
  "_source": {
    "user_id": 2,
    "introduction": "ruby developer",
    "occupation_name": "ruby developer"
  },
  "_explanation": {
    "value": 0.45840853,
    "description": "max of:",
    "details": [
      {
        "value": -1.1157178,
        "description": "weight(occupation_name:ruby in 0) [PerFieldSimilarity], result of:",
        "details": [
          {
            "value": -1.1157178,
            "description": "score(freq=1.0), product of:",
            "details": [
              {
                "value": 11,
                "description": "boost",
                "details": []
              },
              {
                "value": -0.22314355,
                "description": "idf, computed as log(1 + (N - n + 0.5) / (n + 0.5)) from:",
                "details": [
                  {
                    "value": 2,
                    "description": "n, number of documents containing term",
                    "details": []
                  },
                  {
                    "value": 1,
                    "description": "N, total number of documents with field",
                    "details": []
                  }
                ]
              },
...

```

---

<div class="post-metadata">

**Author:** ![jpountz](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jpountz/32/45836_2.png) [@jpountz](https://discuss.elastic.co/u/jpountz)\
**Post date:** [July 22, 2019, 2:33pm UTC](https://discuss.elastic.co/t/query-can-return-negative-score-i-couldnt-find-any-spec-on-documentation-the-minimum-value-of-score-is-not-0/191307/9 "2019-07-22T14:33:05Z")

</div>

Thanks for reporting this. It is a bug. I opened [https://github.com/elastic/elasticsearch/issues/44700](https://github.com/elastic/elasticsearch/issues/44700).

---

<div class="post-metadata">

**Author:** ![hangu\_choi](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/hangu_choi/32/49745_2.png) [@hangu\_choi](https://discuss.elastic.co/u/hangu_choi)\
**Post date:** [July 23, 2019, 12:12am UTC](https://discuss.elastic.co/t/query-can-return-negative-score-i-couldnt-find-any-spec-on-documentation-the-minimum-value-of-score-is-not-0/191307/10 "2019-07-23T00:12:50Z")

</div>

Thank you!

---

<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [August 20, 2019, 12:12am UTC](https://discuss.elastic.co/t/query-can-return-negative-score-i-couldnt-find-any-spec-on-documentation-the-minimum-value-of-score-is-not-0/191307/11 "2019-08-20T00:12:57Z")

</div>

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