Searching in same condition but different scoring

Elastic Stack Elasticsearch
1

I use ES5.1.1
query is as below

index/type/_search
{ 
  "query": {
    "term": {
      "status": "ZA"
    }
  }
}

Conditions
all data have status field.
ZA is full match value.

result by explain API

{
  "_index": "index",
  "_type": "type",
  "_id": "1010999",
  "matched": true,
  "explanation": {
    "value": 6.4028416,
    "description": "sum of:",
    "details": [
      {
        "value": 6.4028416,
        "description": "weight(status:ZA in 0) [PerFieldSimilarity], result of:",    ----(status:ZA in 0) is different from the other result.
        "details": [
          {
            "value": 6.4028416,
            "description": "score(doc=0,freq=1.0 = termFreq=1.0\n), product of:",
            "details": [
              {
                "value": 6.4028416,
                "description": "idf(docFreq=151, docCount=91438)",
                "details": []
              },
              {
                "value": 1,
                "description": "tfNorm, computed from:",
                "details": [
                  {
                    "value": 1,
                    "description": "termFreq=1.0",
                    "details": []
                  },
                  {
                    "value": 1.2,
                    "description": "parameter k1",
                    "details": []
                  },
                  {
                    "value": 0,
                    "description": "parameter b (norms omitted for field)",
                    "details": []
                  }
                ]
              }
            ]
          }
        ]
      },
      {
        "value": 0,
        "description": "match on required clause, product of:",
        "details": [
          {
            "value": 0,
            "description": "# clause",
            "details": []
          },
          {
            "value": 1,
            "description": "*:*, product of:",
            "details": [
              {
                "value": 1,
                "description": "boost",
                "details": []
              },
              {
                "value": 1,
                "description": "queryNorm",
                "details": []
              }
            ]
          }
        ]
      }
    ]
  }
}

{
  "_index": "index",
  "_type": "type",
  "_id": "1112675",
  "matched": true,
  "explanation": {
    "value": 6.345958,
    "description": "sum of:",
    "details": [
      {
        "value": 6.345958,
        "description": "weight(status:ZA in 10849) [PerFieldSimilarity], result of:",      ----(status:ZA in 10849) part is different from the other result.
        "details": [
          {
            "value": 6.345958,
            "description": "score(doc=10849,freq=1.0 = termFreq=1.0\n), product of:",
            "details": [
              {
                "value": 6.345958,
                "description": "idf(docFreq=163, docCount=93224)",
                "details": []
              },
              {
                "value": 1,
                "description": "tfNorm, computed from:",
                "details": [
                  {
                    "value": 1,
                    "description": "termFreq=1.0",
                    "details": []
                  },
                  {
                    "value": 1.2,
                    "description": "parameter k1",
                    "details": []
                  },
                  {
                    "value": 0,
                    "description": "parameter b (norms omitted for field)",
                    "details": []
                  }
                ]
              }
            ]
          }
        ]
      },
      {
        "value": 0,
        "description": "match on required clause, product of:",
        "details": [
          {
            "value": 0,
            "description": "# clause",
            "details": []
          },
          {
            "value": 1,
            "description": "*:*, product of:",
            "details": [
              {
                "value": 1,
                "description": "boost",
                "details": []
              },
              {
                "value": 1,
                "description": "queryNorm",
                "details": []
              }
            ]
          }
        ]
      }
    ]
  }
}

Result scores are different.
Is there any reason that scores are different?

Any tips??

2

My guess is that the documents reside in different shards and therefore
have different IDF values for the same term. Try using dfs-query-then-fetch
to see if that changes anything.
https://www.elastic.co/guide/en/elasticsearch/reference/current/search-request-search-type.html#dfs-query-then-fetch

1 Like
3

Thank you for reply.

It helped me a lot to understand why score was different.

I found this article as well.
To help someone who gets same issue, here is the answer as well.

4

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