I have an ES index with a property that contains a list of nested objects with {"name": "string"} shape. I need to query documents that have at least a certain number of objects matching a given list of names. But setting mimimum_should_match to a value greater than 1 returns no documents contrary to what is expected.

Reproduction :

1. Create test index

PUT /test
{
    "mappings": {
        "properties": {
            "skills": {
                "properties": {
                    "name": {
                        "type": "keyword"
                    }
                },
                "type": "nested"
            }
        }
    }
}

2. Add a few documents

POST /test/_bulk
{ "index" : { "_index" : "test" } }
{ "skills" : [{"name": "python"}, {"name": "css"}, {"name": "java"}] }
{ "index" : { "_index" : "test" } }
{ "skills" : [{"name": "python"}] }
{ "index" : { "_index" : "test" } }
{ "skills" : [{"name": "python"}, {"name": "css"}, {"name": "html"}] }
{ "index" : { "_index" : "test" } }
{ "skills" : [{"name": "python"}, {"name": "css"}, {"name": "java"}, {"name": "photoshop"}, {"name": "js"}] }
{ "index" : { "_index" : "test" } }
{ "skills" : [{"name": "python"}, {"name": "git"}] }
{ "index" : { "_index" : "test" } }
{ "skills" : [{"name": "python"}, {"name": "css"}, {"name": "java"}, {"name": "react"}] }

I would like to return documents that have at least two of the skills ["python", "css", "java"].

The query below returns no documents.

{
    "highlight": {
        "fields": {
            "*": {}
        }
    },
    "query": {
        "nested": {
            "path": "skills",
            "query": {
                "bool": {
                    "minimum_should_match": 2,
                    "should": [
                        {
                            "match": {
                                "skills.name": "python"
                            }
                        },
                        {
                            "match": {
                                "skills.name": "css"
                            }
                        },
                        {
                            "match": {
                                "skills.name": "java"
                            }
                        }
                    ]
                }
            }
        }
    }
}

The same query with "minimum_should_match":1 returns as expected all 6 documents. As you can see in the highlights more that a single skill is matched.

POST /test/_search | jq ".hits.hits[].highlight"
{
  "skills.name": [               <=========== id of this document is aRN7uoUBoT40NEdPkl68
    "<em>python</em>",
    "<em>css</em>",
    "<em>java</em>"
  ]
}
{
  "skills.name": [
    "<em>python</em>",
    "<em>css</em>",
    "<em>java</em>"
  ]
}
{
  "skills.name": [
    "<em>python</em>",
    "<em>css</em>",
    "<em>java</em>"
  ]
}
{
  "skills.name": [
    "<em>python</em>",
    "<em>css</em>"
  ]
}
{
  "skills.name": [
    "<em>python</em>"
  ]
}
{
  "skills.name": [
    "<em>python</em>"
  ]
}

If I try to explain why the first document is not matched with the query having minimum_should_match=2 this is the output

{
    "_id": "aRN7uoUBoT40NEdPkl68",
    "_index": "test",
    "_type": "_doc",
    "explanation": {
        "description": "Not a match",
        "details": [],
        "value": 0.0
    },
    "matched": false
}

The same behavior if I switch match to term.

CodePudding user response：

I get 4 results when minimal match is 2. I had change the query to match separately each skill name.

{
  "highlight": {
    "fields": {
      "*": {}
    }
  },
  "query": {
    "bool": {
      "minimum_should_match": 2,
      "should": [
        {
          "nested": {
            "path": "skills",
            "query": {
              "match": {
                "skills.name": "python"
              }
            }
          }
        },
        {
          "nested": {
            "path": "skills",
            "query": {
              "match": {
                "skills.name": "css"
              }
            }
          }
        },
        {
          "nested": {
            "path": "skills",
            "query": {
              "match": {
                "skills.name": "java"
              }
            }
          }
        }
      ]
    }
  }
}