Sorting on an aggregation in Elasticsearch

To sort on an aggregation in Elasticsearch, you can use the "order" parameter in the aggregation definition.

Here is an example using the "terms" aggregation:

GET /my_index/_search
{
  "size": 0,
  "aggs": {
    "my_agg": {
      "terms": {
        "field": "my_field",
        "order": {
          "my_metric": "desc"
        }
      },
      "aggs": {
        "my_metric": {
          "avg": {
            "field": "my_numeric_field"
          }
        }
      }
    }
  }
}

In this example, the "terms" aggregation groups documents by the "my_field" field and calculates the average of the "my_numeric_field" field for each group using the "avg" aggregation. The "order" parameter sorts the groups in descending order based on the average calculated by the "my_metric" aggregation.

You can adjust the sorting order by changing the "desc" parameter to "asc" if you want to sort in ascending order. You can also sort based on other metrics or fields by changing the value of the "my_metric" parameter in the "order" parameter.