elasticsearchelasticsearch-scripting

Correction of score results


I would like to know if it is possible to implement this in elastic. Let's say I have documents of this structure.

{
 "title": "text1 text2 text3",
 "score_adj":[
  {"text":"text1", "adj": -2},
  {"text":"text3", "adj": -4}
 ]
}

And I will look for documents where the title contains the word text1, I will find this document, and also, since this word is in score_adj and it has -2, I will decrease the final score by this number. Is it possible to implement such logic? I know that there is script_score that allows you to change the score, but I don’t understand how you can repeat this situation.


Solution

  • Here's one possibility:

    {
      "query": {
        "bool": {
          "must": [
           
            {
              "function_score": {
                "query": {
                  "match": {
                    "title": "text1"
                  }
                },
                "functions": [
                  {
                    "script_score": {
                      "script": {
                        "source": """
                        def found = params._source['score_adj'].find(item -> item.text==params.text);
                        if (found != null) {
                          // adj is always negative so use plus
                          return _score + found.adj
                        }
                        
                        return _score;
                      """,
                        "params": {
                          "text": "text1"
                        }
                      }
                    }
                  }
                ],
                "boost_mode": "replace"
              }
            }
          ]
        }
      }
    }
    

    but it may result in the error

    script score function must not produce negative scores, but got [-1.7123179137706757]

    so you'll have to take that into account. Maybe first multiply the original _score by 10 or something so you're guaranteed not go negative.

    I think it'd be more reasonable to convert the adjs to percentages, not concrete values...