Rescore doesn't support multiple queries

[gmoskovicz]

Rescore implementation currently only support a single query. When you use the fluent API you can only add a single rescore query. If you add multiple queries, a single one will be added.

Easy repro:

            // NameScoreFunction its just a customer FunctionScoreFunctionBase implementation

            var searchresults =
                client.Search<Session>(q => q
                      .Query(mainQuery)
                      .Rescore(r => r.RescoreQuery(rq => rq
                                .Query(qq => qq
                                        .FunctionScore(fs => fs
                                            .Functions(new[] { new NameScoreFunction() { QueryName = "fullname", Field = "fullName" } })
                                ))
                                .QueryWeight(0)
                                .RescoreQueryWeight(1))
                                .WindowSize(200)
                            )
                            .Rescore(r2 => r2
                                .RescoreQuery(rq => rq
                                    .Query(qq => qq
                                        .FunctionScore(fs => fs
                                            .Functions(new[] { new NameScoreFunction() { QueryName = "company name", Field = "companyNames" } 
                                    })))
                                    .QueryWeight(.5)
                                    .RescoreQueryWeight(.5))
                                .WindowSize(200)));

The result of this is the following:

{
    "rescore": {
        "window_size": 200,
        "query": {
            "rescore_query": {
                "function_score": {
                    "functions": [{
                        "name_score": {
                            "field": "companyNames",
                            "query_name": "company name"
                        }
                    }]
                }
            },
            "query_weight": 0.5,
            "rescore_query_weight": 0.5
        }
    },
    "query": {
        "match": {
            "primary_name": {
                "query": "Joe Shmo"
            }
        }
    }
}

Note that the field is companyNames which comes from the second rescore query.

[russcam]

Thanks for submitting @gmoskovicz 👍

This is a bug; you can work around it for the moment using the low level client and specifying the query using an anonymous type

    var rs = client.LowLevel.Search<SearchResponse<T>>("index", "type", new
    {
        query = new
        {
            match = new
            {
                field1 = new
                {
                    @operator = "or",
                    query = "the quick brown",
                    type = "boolean"
                }
            }
        },
        rescore = new object[] {
            new {
                window_size = 100,
                query = new {
                    rescore_query = new {
                        match = new {
                           field1 = new {
                              query = "the quick brown",
                              type = "phrase",
                              slop = 2
                           }
                        }
                    },
                    query_weight = 0.7,
                     rescore_query_weight = 1.2
                }
            },
            new {
                window_size = 10,
                query = new {
                    score_mode = "multiply",
                    rescore_query = new {
                        function_score = new {
                            script_score = new {
                                script = "log10(doc['numeric'].value + 2)"
                            }
                        }
                    },
                    query_weight = 0.7,
                    rescore_query_weight = 1.2
                }
            }
         }
    });

which yields the query DSL

POST http://localhost:9200/index/type/_search 
{
  "query": {
    "match": {
      "field1": {
        "operator": "or",
        "query": "the quick brown",
        "type": "boolean"
      }
    }
  },
  "rescore": [
    {
      "window_size": 100,
      "query": {
        "rescore_query": {
          "match": {
            "field1": {
              "query": "the quick brown",
              "type": "phrase",
              "slop": 2
            }
          }
        },
        "query_weight": 0.7,
        "rescore_query_weight": 1.2
      }
    },
    {
      "window_size": 10,
      "query": {
        "score_mode": "multiply",
        "rescore_query": {
          "function_score": {
            "script_score": {
              "script": "log10(doc['numeric'].value + 2)"
            }
          }
        },
        "query_weight": 0.7,
        "rescore_query_weight": 1.2
      }
    }
  ]
}

[russcam]

Fixed with #2095. Will go into next 2.x release