Sorting parent documents based on the score of a nested child

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1

Hello,

i have the following mapping:

{
  "indexname": {
    "mappings": {
      "object": {
        "properties": {
          "languagedata": {
            "type": "nested",
            "properties": {
              "language": {
                "type": "keyword"
              },
              "title": {
                "type": "text",
                "fields": {
                  "keyword": {
                    "type": "keyword"
                  }
                },
                "analyzer": "standard_lowercase_asciifolding_sort"
              }
            }
          },
          "id": {
            "type": "integer"
          }
        }
      }
    }
  }
}

Is it possible to sort the parent documents based on the score, when doing a match query on the nested object 'languagedata'?

{
  "sort": [
    {
      "_score": {
        "mode": "max",
        "order": "desc",
        "nested_path": "languagedata",
        "nested_filter": {
          "bool": {
            "must": [
              {
                "match": {
                  "languagedata.title": "search_phrase"
                }
              }
            ],
            "filter": [
              {
                "term": {
                  "languagedata.language": "de"
                }
              }
            ]
          }
        }
      }
    }
  ]
}

I know that my sort-example will not work, but it is only an example that shows what I want to do.

Thanks for your help
Uli

2

The nested query already returns a score based on the query on the nested object. If you do not have any query clauses apart from the nested query, then you can go with just sorting on _score, which is the default sort order.

In other words, this should give you the desired sort order:

GET indexname/_search
{
  "query": {
    "nested": {
      "score_mode": "max", 
      "path": "languagedata",
      "query": {
        "bool": {
            "must": [
              {
                "match": {
                  "languagedata.title": "search_phrase"
                }
              }
            ],
            "filter": [
              {
                "term": {
                  "languagedata.language": "de"
                }
              }
            ]
          }
      }
    }
  }
}
1 Like
3

And what can I do, in case of other additional query clauses?

4

You could wrap your nested query in a bool query. You would put the nested query in the must clause, and the other criteria in a filter clause. That way, only your nested query will contribute to the score, and the other clauses will not.

5

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