Elasticsearch - How to get min/max/avg of set of nested documents - elasticsearch

Question

Given the following mapping and documents in Elasticsearch, how would I get the min/max/avg of a set of nested documents that match a certain condition? For instance, how would I get them min age of pet that are dogs? My filter gets the correct people that have dogs, but how do I make the min then calculate against the correct nested documents.
(1) Mapping
{
"myIndex": {
"mappings": {
"person": {
"properties": {
"name": {
"type": "string"
},
"pets": {
"type": "nested",
"properties": {
"age": {
"type": "long"
},
"name": {
"type": "string"
},
"type": {
"type": "string"
}
}
}
}
}
}
}
}
(2) Data
{
"name": "bob",
"pets": [
{
"type": "dog",
"name": "wolfie",
"age": 20
},
{
"type": "cat",
"name": "kitty",
"age": 6
}
]
}
{
"name": "bill",
"pets": [
{
"type": "fish",
"name": "goldie",
"age": 2
},
{
"type": "cat",
"name": "meowie",
"age": 18
}
]
}
(3) Query and aggregation
{
"query": {
"filtered": {
"filter": {
"nested": {
"path": "pets",
"filter" : {
"terms": {
"pets.type": ["dog"]
}
}
}
}
}
},
"aggs": {
"minage": {
"nested": {
"path": "pets"
},
"aggs": {
"minage": {
"min": {
"field": "age"
}
}
}
}
}
}

Answer 1

I think you can get what you want with a combination of filter aggregation and the nested filter's join option.
This code worked for me:
DELETE /test_index
PUT /test_index
{
"settings": {
"number_of_shards": 1
},
"mappings": {
"person": {
"properties": {
"name": {
"type": "string"
},
"pets": {
"type": "nested",
"properties": {
"age": {
"type": "long"
},
"name": {
"type": "string"
},
"type": {
"type": "string"
}
}
}
}
}
}
}
PUT /test_index/person/1
{
"name": "bob",
"pets": [
{
"type": "dog",
"name": "wolfie",
"age": 20
},
{
"type": "cat",
"name": "kitty",
"age": 6
}
]
}
PUT /test_index/person/2
{
"name": "bill",
"pets": [
{
"type": "fish",
"name": "goldie",
"age": 2
},
{
"type": "cat",
"name": "meowie",
"age": 18
}
]
}
PUT /test_index/person/3
{
"name": "john",
"pets": [
{
"type": "dog",
"name": "oldie",
"age": 25
}
]
}
POST /test_index/_search?search_type=count
{
"aggs": {
"minage_1": {
"nested": {
"path": "pets"
},
"aggs": {
"minage_2": {
"filter": {
"nested": {
"path": "pets",
"filter": {
"terms": {
"pets.type": [
"dog"
]
}
},
"join": false
}
},
"aggs": {
"min_age_3": {
"min": {
"field": "age"
}
}
}
}
}
}
}
}
...
{
"took": 2,
"timed_out": false,
"_shards": {
"total": 1,
"successful": 1,
"failed": 0
},
"hits": {
"total": 3,
"max_score": 0,
"hits": []
},
"aggregations": {
"minage_1": {
"doc_count": 5,
"minage_2": {
"doc_count": 2,
"min_age_3": {
"value": 20
}
}
}
}
}