Filter results by the length of the nested objects returned, similar to min_child

[Dustin_Silk]

I'm trying to filter my results based on the number of nested objects found for a document.
I've tried using scores but I cant get scores to work with filters, and I've tried a script but can't get that working either.

Below are more details on all of it. Basically I need to:

• Filter the parent documents by their properties
• Filter each nested object by a few properties
• Finally, filter the parent document by the number of nested documents remaining to a single fixed number

These are my mappings:

    "mappings": {
      "properties": {
        "dates" : {
          "type" : "nested",
          "properties" : {
            "rooms" : {
              "type" : "integer"
            },
            "timestamp" : {
              "type" : "long"
            }
          }
        },
        "doc_id" : {
          "type" : "text"
        },
        "distance" : {
          "type" : "integer"
        }
        ...
      }
    }

Example data

    PUT /test/_doc/1
    {
      "doc_id": "1",
      "distance": 1,
      "dates": [
        {
          "rooms": 1,
          "timestamp": 1
        },
        {
          "rooms": 1,
          "timestamp": 2
        },
        ...
      ]
    }

There are unknown number of nested dates, but won't be more than ~15 per document. I'm filtering by parent and nested child values.

My attempt using a script:

    GET /test/_search
    {
      "query": {
        "bool" : {
          "filter": [
            { "range": { "distance": { "lt": 5 }}},
            {
              "nested": {
                "path": "dates",
                "query": {
                  "bool": {
                    "filter": [
                      { "range": { "dates.rooms": { "gte": 1 } } },
                      { "range": { "dates.timestamp": { "lte": 2 }}},
                      { "range": { "dates.timestamp": { "gte": 1 }}}
                    ]
                  }
                }
              }
            },
            {
              "script": {
                "script": {
                  "source": "doc['dates'].length = 2",
                  "lang": "painless"
                }
              }
            }
          ]
        }
      }
    }

This throws an error: No field found for [dates] in mapping with types []

So I've tried to follow this solution here

Attempt using scoring

    GET /test/_search
    {
      "query" : {
        "function_score": {
          "min_score": 20,
          "boost": 1,
          "functions": [
            {
              "script_score": {
                "script": {
                    "source": "if (_score > 20) { return - 1; } return _score;"
                }
              }
            }
          ],
          "query": {
            "bool" : {
              "filter": [
                { "range": { "distance": { "lt": 5 }}},
                {
                  "nested": {
                    "score_mode": "sum",
                    "boost": 10,
                    "path": "dates",
                    "query": {
                      "bool": {
                        "filter": [
                          { "range": { "dates.rooms": { "gte": 1 } } },
                          { "range": { "dates.timestamp": { "lte": 2 }}},
                          { "range": { "dates.timestamp": { "gte": 1 }}}
                        ]
                      }
                    }
                  }
                }
              ]
            }
          }
        }
      }
    }

But Scoring doesnt work with filters and I can't seem to get this working at all.
Would really appreciate any help on this topic.

Thanks!

[spinscale (Alexander Reelsen)]

Hey,

how about storing the size of the array in an extra field when indexing, so that your query for the size of the array becomes a range query and will be much much faster than the script one?

--Alex