Max Aggregation

A single-value metrics aggregation that keeps track and returns the maximum value among the numeric values extracted from the aggregated documents. These values are extracted from specific numeric fields in the documents.

Structuring

The following snippet captures the structure of max aggregations:

"<aggregation_name>": {
  "_max": {
    "_field": "<field_name>"
  },
  ...
}

Field

The <field_name> in the _field parameter defines the specific field from which the numeric values in the documents are extracted and used to compute the returned maximum value.

Assuming the data consists of documents representing bank accounts, as shown in the sample dataset of Data Exploration section, computing the max balance value across all accounts:

SEARCH /bank/

{
  "_query": "*",
  "_limit": 0,
  "_check_at_least": 1000,
  "_aggs": {
    "max_balance": {
      "_max": {
        "_field": "balance"
      }
    }
  }
}

Response:

{
  "aggregations": {
    "_doc_count": 1000,
    "max_balance": {
      "_max": 12699.46
    }
  }, ...
}

As can be seen, the name of the aggregation (max_balance above) also serves as the key by which the aggregation result can be retrieved from the returned response.