Min_score for a "must" in a bool query in Elasticsearch

Question

Is there a way to apply a minimum score to a must clause in a bool query in elasticsearch.

I want to be able to do something like this:

{
  "query": {
     "bool": {
        "must": [
            {
              "match": {
                 "name": {
                    "query":"A Name",
                    "min_score": 0.3
                 }
               }
            },
            {
              "match": {
                 "address": {
                    "query":"1 Somewhere Street, Somewhereset, UK",
                    "min_score": 0.3
                 }
               }
            }
        ]
    }
  }
}

Which would require the name query to match with a score > 0.3 and the address query to match with a score > 0.3 for the document to be returned. This is to stop really good name matches being returned despite having a terrible address match (e.g. just matching the 1) and vice versa.

I'm currently using Elasticsearch 1.5, but I've also wanted this in the past for 2.3.

Specifying the version of Elastic can help a lot with some questions - there are may differences between v1 and v2. — harvzor, Jul 21 '16 at 12:05

score 3 · Accepted Answer · answered Jul 21 '16 at 21:07

Try this and let me know if it works:

{
  "query": {
    "bool": {
      "must": [
        {
          "function_score": {
            "query": {
              "match": {
                "name": {
                  "query": "A Name"
                }
              }
            },
            "min_score": 0.3
          }
        },
        {
          "function_score": {
            "query": {
              "match": {
                "address": {
                  "query": "1 Somewhere Street, Somewhereset, UK"
                }
              }
            },
            "min_score": 0.3
          }
        }
      ]
    }
  }
}

That works great. I had thought of using a function score query, but I was thinking I'd need to use the function to make the score go so low it would not get past the overall min score. Also, I was expecting it to be too slow to be practical, but it doesn't seem any slower at all, as it's not actually using a function. Thanks. — kiml42, Jul 22 '16 at 09:32

score 0 · Answer 2 · answered Jul 21 '16 at 13:11

It seems that the score of a query is calculated from all of the fields combined. You can change how the score is calculated using the script_score in a function query: https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-function-score-query.html#function-script-score

However, it seems unlikely that you can access the score of each field result individually.

Min_score for a "must" in a bool query in Elasticsearch

2 Answers2