OpenSearch/docs/reference/aggregations/bucket/nested-aggregation.asciidoc

[[search-aggregations-bucket-nested-aggregation]]
=== Nested Aggregation

A special single bucket aggregation that enables aggregating nested documents.

For example, lets say we have an index of products, and each product holds the list of resellers - each having its own
price for the product. The mapping could look like:

[source,js]
--------------------------------------------------
PUT /index
{
    "mappings": {
        "properties" : {
            "resellers" : { <1>
                "type" : "nested",
                "properties" : {
                    "name" : { "type" : "text" },
                    "price" : { "type" : "double" }
                }
            }
        }
    }
}
--------------------------------------------------
// CONSOLE
// TESTSETUP
<1> The `resellers` is an array that holds nested documents under the `product` object.

The following aggregations will return the minimum price products can be purchased in:

[source,js]
--------------------------------------------------
GET /_search
{
    "query" : {
        "match" : { "name" : "led tv" }
    },
    "aggs" : {
        "resellers" : {
            "nested" : {
                "path" : "resellers"
            },
            "aggs" : {
                "min_price" : { "min" : { "field" : "resellers.price" } }
            }
        }
    }
}
--------------------------------------------------
// CONSOLE
// TEST[s/GET \/_search/GET \/_search\?filter_path=aggregations/]
// TEST[s/^/PUT index\/_doc\/0\?refresh\n{"name":"led", "resellers": [{"name": "foo", "price": 350.00}, {"name": "bar", "price": 500.00}]}\n/]

As you can see above, the nested aggregation requires the `path` of the nested documents within the top level documents.
Then one can define any type of aggregation over these nested documents.

Response:

[source,js]
--------------------------------------------------
{
  ...
  "aggregations": {
    "resellers": {
      "doc_count": 0,
      "min_price": {
        "value": 350
      }
    }
  }
}
--------------------------------------------------
// TESTRESPONSE[s/\.\.\.//]
// TESTRESPONSE[s/: [0-9]+/: $body.$_path/]