Excluding inner hits from top hits aggregation with source filter - elasticsearch

Question

In my query, I am using the inner_hits to return the list of nested objects that match my query.
I then add an aggregations for categoryId of my document, and then a top hit aggregation to get the display name for that category.
"aggs": {
"category": {
"terms": {
"field": "categoryId",
"size": 100
},
"aggs": {
"category_value": {
"top_hits": {
"size": 1,
"_source": {
"includes": "categoryName"
}
}
}
}
}
}
Now, when I look at the aggregation buckets, I do get a _source document with only the categoryName property, but I also get the entire inner_hits collection:
{
...
"_source": {
"categoryName": "Armchairs"
},
"inner_hits": {
"my_inner_hits": {
"hits": {
"total": 260,
"max_score": null,
"hits": [{
...
"_source": {
//nested document here
}
}
]
}
}
}
}
Is there a way to not include the inner_hits data in a top_hits aggregation?

Answer 1

Since you only need a single field, what I suggest you to do is to get rid of top_hits aggregation and use another terms aggregation for the name:
{
...
"aggs": {
"category": {
"terms": {
"field": "categoryId",
"size": 100
},
"aggs": {
"category_value": {
"terms": {
"field": "categoryName",
"size": 1
}
}
}
}
}
}
That will also be a little bit more efficient.
UPDATE:
Another way to keep using terms/top_hits is to leverage response filtering and only return what you need. For instance, appending this to your URL will make sure that you won't find any inner hits inside your aggregation
?filter_path=hits.hits,aggregations.**.key,aggregations.**.doc_count,aggregations.**.hits.hits.hits._source