how to find the nearest / closest number using Query DSL in elasticsearch

Question

i am looking for a possibility to find the nearest price / number with the help of elasticsearch. the problem is that i do not have a range. what i want to achieve is that the results are sorted by nearest distance. according to the example search query my index contains 3 documents with the following prices (numbers): 45, 27, 32

the "distance" from my search value 29 for the given numbers are 45 - 29 = 16 | 27 - 29 = -2 | 32 - 29 = 3 so what i would expect is that the search results are scored by the "distance" the number is away from the given price.

search query example:

GET myawesomeindex/_search
{
  "query": {
    "bool": {
      "should": [
        {
          "match": {
            "description": "this is the text i want to find"
          }
        },
        {
          "match": {
            "price": 29
          }
        }
      ]
    }
  }
}

i think my question is related to this similar question: Elasticsearch scoring based on how close a number is to a query

Answer 1

There you go:

  "sort": {
    "_script": {
      "type": "number",
      "script": "return doc['price'].value-distance",
      "params": {
        "distance": 29
      },
      "lang": "groovy",
      "order": "desc"
    }
  }

And you need to enable dynamic scripting.

You can, also, do it like this

  "query": {
    "function_score": {
      "query": {
        "bool": {
          "should": [
            {
              "match": {
                "description": "this is the text i want to find"
              }
            },
            {
              "match": {
                "price": 29
              }
            }
          ]
        }
      },
      "functions": [
        {
          "exp": {
            "price": {
              "origin": "29",
              "scale": "1",
              "decay": 0.999
            }
          }
        }
      ]
    }
  }

But this will alter the score itself. If you want pure sorting by the distance (and nothing else) then I believe the first option is the best.