Elasticsearch rescore all results ignoring base score

Question

I'm trying to rescore my results with the following query:

POST /archive/item/_search
{
    "query": {
        "multi_match": {
            "fields": ["title", "description"],
            "query": "1 złoty",
            "operator": "and"
        }
    },
    "rescore": {
        "window_size": 50,
        "query": {
            "rescore_query": {
                "multi_match": {
                    "type": "phrase",
                    "fields": ["title", "description"],
                    "query": "1 złoty",
                    "slop": 10
                }
            },
            "query_weight": 0,
            "rescore_query_weight": 1
        }
    }
}

I'm doing this because I want to score by proximity mainly. Also, I want to ignore source field length impact on the score. Am I doing this right? If not, what's the best practice here?

And the second question. Why window_size is needed anyway? I don't want top results only. The main query atcs like a filter, so all the results it returns are relevant. I quess something like "window_size": "all" would be perfect, but I couldn't find anything in the docs.

score 1 · Answer 1 · answered Jul 17 '14 at 02:33

To answer your second question, the reason it's needed is because it's designed to be for top results only. Basically it's a cost issue - the assumption is that the secondary algorithm is more expensive so it was only designed to be run on the top results. There's more discussion about this here:

https://github.com/elasticsearch/elasticsearch/issues/2640

and here:

http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/search-request-rescore.html

Personally I think the "all" option is a great idea, maybe you should open an issue on github?

score 0 · Answer 2 · edited May 23 '17 at 10:29

If you want to score with proximity match all results returned by some other filter this should do:

{
  "query": {
    "filtered" : {
      "query" : {
        "multi_match": {
          "type": "phrase",
          "fields": ["title", "description"],
          "query": "1 złoty",
          "slop": 10
        }
      },
      "filter" : {
        "query": {
          "multi_match": {
            "fields": ["title", "description"],
            "query": "1 złoty",
            "operator": "and"
          }
        }
      }
    }
  }
}

According to this, the filter is run before the query, so the performance shouldn't be bad as well. What's more you don't score twice, because filters don't calculate scores. Another advantage is that filters can be cached which should speed things significantly.

Keep in mind that I did short tests only, mostly focusing on syntax not results. You might want to double check it.

Elasticsearch rescore all results ignoring base score

2 Answers2