Elasticsearch: Filter/Query support inside Top hits Aggregation

[sumitjainn]

Elasticsearch documentation states that The top_hits aggregation returns regular search hits, because of this many per hit features can be supported

https://www.elastic.co/guide/en/elasticsearch/reference/2.1/search-aggregations-metrics-top-hits-aggregation.html

Crucially, the list includes _Named filters and queries_ But trying to add any filter or query throws SearchParseException: Unknown key for a START_OBJECT. So, it looks like the documentation is wrong.

Stack overflow question: http://stackoverflow.com/questions/34319337/filter-query-support-in-elasticsearch-top-hits-aggregation

[spinscale]

Indeed the TopHitsParser does not seem able to parse query/filters via the SubSearchContext, but maybe I am misreading the source. Maybe @martijnvg can clarify here.

Thinking if you can try a filter aggregation and nest the top_hits inside of that one?

[martijnvg]

@sumitjainn This is for filters and queries that have the _name option set in the main query. So hits returned by the top_hits agg can included reference to named queries/filters used in the main query. It isn't possible to add a query/filter to the top_hits agg.

[sumitjainn]

Thanks for clearing it up @martijnvg. @spinscale Yes, indeed, filter aggregations does the trick, was just curious about the correctness of the documentation.

[spinscale]

thx for responding. closing then!

[digitalkaoz]

@sumitjainn can you post an example here? trying to do some filtering on the docs of a top_hits aggregation, but didnt have any luck here... maybe @spinscale has an opinion too?

[dukenguyen]

I'm also unable to do this. @sumitjainn or @spinscale , do you have an example please?

[itaydvir]

@digitalkaoz @dukenguyen - i think they meant to wrap it with filter aggregation.
This is what i did:

"aggregations": {
    "last_document_of_specific_doc_types": {
        "filter": {
            "terms": {
                "doc_types": [161, 162]
            }
        },
        "aggregations": {
            "latest": {
                "top_hits": {
                    "size": 1,
                    "_source": [
                        "creationDate"
                    ],
                    "sort": {
                        "creationDate": "desc"
                    }
                }
            }
        }
    }
}

[nick250386]

@itaydvir
If I want to access a field from the result returned by top_hits:(example below)

"aggregations": {
    "last_document_of_specific_doc_types": {
        "filter": {
            "terms": {
                "doc_types": [
                    161,
                    162
                ]
            }
        },
        "aggregations": {
            "latest": {
                "top_hits": {
                    "size": 1,
                    "_source": [
                        "creationDate",
                        "required"
                    ],
                    "sort": {
                        "creationDate": "desc"
                    },
                    "script_fields": {
                        "reqd_flag": {
                            "script": {
                                "lang": "painless",
                                "inline": "params['_source']['required'] == 'Y' ? 0 : 1"
                            }
                        }
                    }
                }
            }
        }
    }
}

How can I access the source field "required" or the scripted field "reqd_flag" outside this aggregation ? If not, then can you suggest an alternative to this. Am I missing or doing something wrong ?