How to get the count of a pair of field values? - elasticsearch

Question

I need to build a heatmap from the data I have in elasticsearch. The heatmap is the count of cases where two specific fields have the same value. For the data
{'name': 'john', 'age': '10', 'car': 'peugeot'}
{'name': 'john', 'age': '10', 'car': 'audi'}
{'name': 'john', 'age': '12', 'car': 'fiat'}
{'name': 'mary', 'age': '3', 'car': 'mercedes'}
I would like to get the number of unique pairs for the values of name and age. That would be
john, 10, 2
john, 12, 1
mary, 3, 1
I could get all the events and make the count myself but I was hoping that there would be some magical aggregation which could provide that.
It would not be a problem to have it in a nested form, such as
{
'john':
{
'10': 2,
'12': 1
},
'mary':
{
'3': 1
},
}
or whatever is practical.

Answer 1

You can use Inner aggregation. Use query like
POST count-test/_search
{
"size": 0,
"aggs": {
"group By Name": {
"terms": {
"field": "name"
},
"aggs": {
"group By age": {
"terms": {
"field": "age"
}
}
}
}
}
}
Output won't be like as you mentioned but like.
"aggregations": {
"group By Name": {
"doc_count_error_upper_bound": 0,
"sum_other_doc_count": 0,
"buckets": [
{
"key": "john",
"doc_count": 3,
"group By age": {
"doc_count_error_upper_bound": 0,
"sum_other_doc_count": 0,
"buckets": [
{
"key": "10",
"doc_count": 2
},
{
"key": "12",
"doc_count": 1
}
]
}
},
{
"key": "mary",
"doc_count": 1,
"group By age": {
"doc_count_error_upper_bound": 0,
"sum_other_doc_count": 0,
"buckets": [
{
"key": "3",
"doc_count": 1
}
]
}
}
]
}
}
Hope this helps!!

Answer 2

You can use a term aggregation with a script:
https://www.elastic.co/guide/en/elasticsearch/reference/current/search-aggregations-bucket-terms-aggregation.html#_multi_field_terms_aggregation
Like this you can "concat" what you want such as :
{
"aggs" : {
"data" : {
"terms" : {
"script" : {
"source": "doc['name'].value + doc['name'].age",
"lang": "painless"
}
}
}
}
}
(Not sure about the string concat syntax).