Compose nested aggregations - elasticsearch

Question

Im sorry for any english misstake.
i hope that someone can help me.
Supose that i have the following mapping to my index:
PUT test-index
{
"mappings": {
"properties": {
"nestedOBJField": {
"type": "nested",
"index": true
},
"keywordField": {
"type": "keyword",
"index": true
}
}
}
}
It is possible to use the composite feature with nested fields?
It will be very handful if i can do something like this:
GET /test-index/_search
{
"size": 0,
"aggs": {
"TestAgg": {
"composite": {
"size": 10000,
"sources": [
{
"keyWordFieldAgg": {
"terms": {
"field": "keyWordField"
}
},
{
"nestedFieldAgg": {
"terms": {
"field": "nestedOBJField.attribute"
}
}
}
]
}
}
}
}
But this aproach is returning a several number of errors.
I will appreciate a lot if someone can help

Answer 1

Property nestedOBJField is of data type "nested" and property keyWordField is keyword type and at same level as nestedOBJField.
To use nested fields in aggregation , you need to use nested aggregation but then all sources in composite aggegation must be of type nested. This open issue can tell more about it.
You can use following work arounds.
Move keyWordField inside nested object in your documents.
{
"mappings": {
"properties": {
"nestedOBJField": {
"type": "nested",
"properties":{
"keywordField": {
"type": "keyword"
}
}
}
}
}
}
Sample Document
{
"nestedOBJField":[
{
"attribute":"1",
"age":1,
"keywordField":"xyz"
},
{
"attribute":"2",
"age":2,
"keywordField":"xyz"
}
]
}
Query
"aggs": {
"TestAgg": {
"nested": {
"path": "nestedOBJField"
},
"aggs": {
"name": {
"composite": {
"size": 10000,
"sources": [
{
"nestedFieldAgg": {
"terms": {
"field": "nestedOBJField.attribute.keyword"
}
}
},
{
"a":{
"terms": {
"field": "nestedOBJField.keywordField.keyword"
}
}
}
]
}
}
}
}
}
Moving your field inside nested property will mean data duplication , updating data in all nested documents.
Using terms aggregation - pagination will be an issue in this case
{
"size": 0,
"aggs": {
"TestAgg": {
"nested": {
"path": "nestedOBJField"
},
"aggs": {
"name": {
"terms": {
"field": "nestedOBJField.attribute.keyword",
"size": 10
},
"aggs": {
"back_to_parent": {
"reverse_nested": {},
"aggs": {
"keywords": {
"terms": {
"field": "keywordField.keyword",
"size": 10
}
}
}
}
}
}
}
}
}
}